Monday Feb 17 handouts

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  • Lecture Handouts

    Monday,

    17th Feb, 2014

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    1

    Short Course on Seismic Design of Reinforced and Confined Masonry Buildings

    February 17-21, 2014, IIT Gandhinagar, India

    MasonryConstructionAroundtheWorld:anOverview

    Welcome to the World of Masonry!

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    2

    No. 3

    TomSchacher,SwitzerlandRichardKlingner/MasonrySociety,USADurgeshRai,IITKanpur,IndiaC.V.R.Murty,IITJodhpur,IndiaSudhirJain,IITGandhinagar,IndiaBillMcEwen,MasonryInstituteofBC,CanadaMarcialBlondet,PUCP,Peru

    Acknowledgments

    Topics Introducingspeakersandtheworldofmasonry Unreinforcedmasonry(URM) stone,adobe,claybricks Nominallyreinforcedmasonry Reinforcedmasonry Confinedmasonry

    No. 4

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    3

    UnreinforcedMasonry Masonrywallstructureswithoutanyreinforcement Millionsofexistingunreinforcedmasonrybuildingsaroundtheworld Variousmasonryunits:

    Adobe Stone Claybricksorblocks Concretebricksorblocks

    No. 5

    AdobeMasonry

    Adobemudblocksareoneoftheoldestandmostwidelyusedbuildingmaterials.Useofthesesundriedblocksdatesbackto8000B.C. Around30to50%oftheworldspopulationlivesorworksinearthenbuildings Approximately 50% of population in developing

    countries, including the majority of the rural population and at least 20% of the urban population, live in earthen dwellings

    No. 6

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    4

    No. 7

    HistoricEarthenBuildingsMesopotamia 8,000 BCbeehive domes made of adobe blocks

    Historic Adobe Structures: Ziggurats, Mesopotamia (1250 B.C.)

    No. 8

    Chogha Zanbil, Iran - the complex protected by three concentric walls; the inner area taken up with a great ziggurat dedicated to the main god Inshushinak;

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    5

    HistoricAdobeConstruction:California,USAMisionDolores,OldestBuildinginSanFrancisco(18th century)

    No. 9

    Adobe Housing Construction

    Traditional construction practice followed for centuries in many countries.

    Practiced today by people of low economic status in many countries (especially Asia, Africa, and Latin America)

    Walls made of adobe (unburnt mud) blocks laid in mud mortar. Roof structure: usually timber beams with timber planks

    covered with a mud mortar overlay or with clay tiles or CGI sheets

    This construction is considered to be very vulnerable to earthquake effects

    10

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    6

    11

    Example: Adobe Construction in Peru

    Source: World Housing Encyclopedia

    www.world-housing.net

    12

    Cane Reinforcement for Adobe Construction

    Source: World Housing Encyclopedia web site

    www.world-housing.net

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    7

    13

    Reinforced Adobe ConstructionResearch at the Catholic University of Peru

    14

    Reinforced Adobe Construction

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    8

    15

    Shake-table Tests on Adobe Construction -Catholic University of Peru (PUCP)

    Original unstrengthened building model Strengthened building model

    Source: Marcial Blondet, PUCP, Peru

    FurtherReading:AdobeMasonry

    www.world-housing.net/tutorials/adobe-tutorials16

    Printed copies available from EERI

    www.eeri.org

    Free download:

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    9

    StoneMasonry Traditional form of construction that has been

    practiced for centuries in regions where stone is locally available. Stone buildings range from cultural and

    historical landmarks to simple dwellings built by their owners in developing countries where stone is an affordable and cost-effective building material for housing construction.

    No. 17

    18

    Macchu Picchu, Peru (16th Century)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    10

    Macchu Picchu: Inca Stonework

    No. 1919

    Detail of stone masonry laid without mortar , using joints less than 1 mm thick

    20

    Stone Masonry in Maharastra, India

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    11

    Traditional Building Construction-Maharashtra

    Over85%housingisstonemasonryconstruction Thickstonemasonrywallssupportflattimberroofswithearthenoverlays Climaticconditions:lowrainfallandextremelyhotsummermonths(temperaturesover40C)

    21

    Traditional Building Construction

    22

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    12

    23

    Stone Masonry Walls in Maharashtra, India

    wall thickness ranges from 50 cm to 2 m

    ReconstructionaftertheEarthquake

    24

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    13

    25

    FieldWorkinMaharashtra(199499)

    Manual for earthquake-resistant masonry construction authored by S. Brzev and a team from IIT PowaiPublished by the Government of Maharashtra

    HistoricBrickMasonryConstruction

    Usedforretainingearth,fortificationofcommunities,andenclosingbuildingssinceAncientRome; Kilnfiredbricks constructiontechniquesandqualityrangingwidely; Earlymasonrywallsmortarmadefrommudorbitumenorpozzolana(volcanicash);jointsrangedfrom13mmthicknessto40mmthickness.

    No. 26

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    14

    No. 27

    ForumRomanum(Rome):AnExhibitionofAncientRomanWalls

    No. 28

    ExamplesofRomanWalls

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    15

    The Great Wall of China

    No. 29

    - The construction spanned from 5thcentury BC through the 16th century

    - Various forms of masonry in various periods (bricks, stone, rammed earth)

    - 6,260 km long wall, running generally east-west along the northern edge of China.

    TheGreatWallofChina(contd)

    No. 30

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    16

    ContemporaryUnreinforcedBrickMasonryConstruction

    No. 31

    Example from India Source:Murty (2013)

    BrickMasonryConstruction:Maharashtra,India

    32

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    17

    UnreinforcedBrickMasonry(URM)

    UnreinforcedmasonryispracticedinNorthAmericainareaswithlowseismicity ReinforcedmasonryconstructionstartedinCaliforniaafterthe1933SantaBarbaraearthquake Therearemanyexistingunreinforcedmasonrybuildings someofwhichhavebeenretrofitted

    No. 33

    No. 34

    URMBuildings

    URM Skyscrapers, Chicago, USA, 1890sExample: Monadnock Building, 188916 storiesunreinforced masonry walls6 ft thick at base, 1 ft thick at top

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    18

    UnreinforcedConcreteBlockMasonryBuildings,Santiago,Chile(builtaround1910)

    35

    ConcreteBlocks Chile

    Typical block

    501 mm x 138 mm x 251 mmBlock testing setup

    Compressive strength 25 MPa

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    19

    NominallyReinforcedMasonry Mostlyunreinforced

    Somereinforcementisprovidedatcriticallocationsinverticaland/orhorizontaldirection,e.g.: Verticalreinforcementatdoor/windowopeningsandatwallintersections

    Reinforcedconcrete(RCC)bandsatplinth,lintel,and/orfloorlevel

    No. 37

    RCCBandsinNominallyReinforcedMasonryToEnsureIntegrity

    No. 38Source: Bothara and Brzev (2011)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    20

    RCCBandActslikeaBelt!

    No. 39Source: Bothara and Brzev (2011)

    NominallyReinforcedMasonry:RCCBands

    No. 40

    Source: Bothara and Brzev (2011)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    21

    NominallyReinforcedMasonry

    Demonstration buildling in Bam, Iran after the 2003 earthquake

    Source: T. Schacher

    NominallyReinforcedMasonryExample: Reconstruction after the 2005 Kashmir earthquake in Pakistan

    Source: T. Schacher

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    22

    NominallyReinforcedMasonry

    Documentation in the form of simplified guidelines for Indian zones III, IV and V can be found here:

    www.ndmindia.nic.in/Simplified%20Guideline_Zone%20V.pdf

    (replace V before .pdf with III or IV)

    NominallyReinforcedMasonry:VerticalReinforcement

    Quettabond:pocketstoreceiverebars

    No. 44

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    23

    QuettaBond:ReinforcementDetails

    No. 45

    Earthquake Safe Construction of Masonry Buildings (Arya and Panda)

    ReinforcedMasonry Masonrywallconstructioninwhichreinforcementisembeddedinsuchamannerthattwomaterialsacttogetherinresistingforces.

    Reinforcementresiststensionwhilethemasonryresistscompression.

    Reinforcementusuallyinformofinternalsteelbarsgroutedintomasonryunitsorlaidinhorizontalmortarcourses.

    No. 46

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    24

    Concrete Masonry Block Construction

    ReinforcedMasonryConstructionUsingHollowBlocks

    Hollow concrete blocks Vertical reinforcement placed in hollow cores Horizontal reinforcement: joint reinforcement and/or

    bond beam reinforcement

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    25

    WallReinforcement

    HorizontalReinforcement

    Joint (ladder) reinforcementBond beam reinforcement

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    26

    Reinforcement

    No. 51

    Horizontal Reinforcement

    TypicalMasonryReinforcement

    No. 52

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    27

    Masonry grout is a cementitious mixture used to fill cores or cavities in masonry construction

    Drawing: Grouted brick masonry, USA 1868

    Grouting

    Grouting

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    28

    Grouting

    No. 55

    ReinforcedMasonry:HollowClayBlocks

    No. 56Example from Chile

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    29

    ReinforcedMasonry:HollowClayBlocks

    No. 57Typical reinforcement arrangement, Chile (Moroni, Gomez, and Astroza, World Housing Encyclopedia Report 5)

    Examples from Peru

    58

    MultiPerforatedMasonryUnits:LatinAmericaandEurope

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    30

    ConfinedMasonry

    ConfinedMasonryConstruction:aDefinition

    Confinedmasonryisaconstructionsystemwhere

    thewallsarebuiltfirst,andRCcolumnsandbeams

    arecastafterwards.

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    31

    KeydifferencebetweentheconfinedmasonryandRCframeconstruction=constructionsequence

    ConfinedMasonry Wallsfirst Concretelater

    ReinforcedConcreteFrame Concretefirst Wallslater

    Source: Tom Schacher

    KeyComponentsofaConfinedMasonryBuilding

    Key structural components of a confined masonry building are:

    Masonry walls made either of clay brick or concrete block units

    Tie-columns = vertical RC confining elements whichresemble columns in reinforced concrete frame construction

    Tie-beams = horizontal RC confining elements whichresemble beams in reinforced concrete frame construction.

    62

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    32

    ConfinedMasonryBuilding:KeyComponents

    ConfinedMasonry:Beginnings Evolvedthoughaninformalprocessbasedonitssatisfactoryperformance

    inpastearthquakes

    Thefirstreporteduseinthereconstructionafterthe1908Messina,Italy

    earthquake(M7.2) deathtoll70,000

    PracticedinChileandColumbiasince1930sandinMexicosince1940s

    64

    Currently practiced in several countries/regions with high seismic risk, including Latin America, Mediterranean Europe, Middle East (Iran), South Asia (Indonesia), and the Far East (China).

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    33

    Mexico ElSalvador Indonesia Pakistan

    65

    Confined Masonry Construction Examples

    ConfinedMasonryApartmentBuildings(Chile)

    66

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    34

    KeyElements LayoutRules

    67

    LocationofConfiningElementsisVeryImportant!

    68

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    35

    69

    ConfinedMasonry:ConstructionProcess

    Indonesia (C.Meisl) Slovenia (Lutman and Tomazevic)

    ConfinedMasonryConstruction:Toothing attheWalltoTieColumnInterface

    70

    Toothing enhances interaction between masonry walls and RC confining elements

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    36

    No. 71

    TajMahal:OneoftheMostOutstandingMasonryStructuresintheWorld

    No. 72

    Questions?

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    1

    Short Course on Seismic Design of Reinforced and Confined Masonry Buildings

    February 17-21, 2014, IIT Gandhinagar, India

    MasonryConstructioninMexicoandCanada

    Some facts about Mexico

    Indian Territory 3,287,590 km2Mexican Territory 1,964,375 km2

    [Wikipedia]

    Mexican population 118,395,054 (2013)Indian population 1,239,830,000 (2014)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    2

    Mexico City

    Wikipedia

    Historic CentreMain plaza, government palace

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    3

    Historic Centre

    Main plaza cathedral

    Historic CentrePalace of belle arts

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    4

    Business DistrictWest side, business district

    Some facts about Mexico

    Inhabitantes (thousands) 112,337

    Annual growth rate 1.8

    Medianage 26

    Population density (inhabitants/km2) 57

    Brute mortality per1000inhabitants 5.7

    Child mortality, number ofdead child one year or less per1000born

    12.2

    Life expectancy inyears 75

    Average number ofoccupants perhouse 3.9

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    5

    Some facts about Mexico

    age

    percent

    57.3% 54.9%

    Economic ActivityEconomic activity

    Services Industry Primary

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    6

    Some facts about housingpe

    rcen

    t

    Housing annual growth rate

    Some facts about housing

    Percent of houses with walls made of durable mBrick, concrete, Stone,etc.

    perc

    ent

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    7

    Some facts about housing

    Percent of houses with roof made of durable mconcrete, concrete joists and arched lightened

    perc

    ent

    Some facts about housing

    Percent of individual houses with piped wa

    perc

    ent

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    8

    Some facts about housing

    Percent of houses with electricity

    perc

    ent

    About UNAM

    Juan OGorman

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    9

    UNAM Campus

    A large campus south of Mexico city, green areas withf th i it ( b

    Basic numbers 218,400 Studentscycle20122013

    26,878 Postgraduates 190,707 Undergraduates 815 Nationalmusicschool

    37,610 Academics:teachers,researcherstechniciansetc.(11,889fulltime)

    13Faculties 31Institutes 15centres

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    10

    Budget

    Budget2.59billionUSD(2013)

    62%Teaching 25%Research 8%extensionactivities 5%Management

    The Institute of Engineering 94 Researchers 101Technicians 500students

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    11

    ResearchinMexicoCompression strength for different types of masonry

    (Meli y Hernndez, 1971); Meli (1979)

    Largetestprogram70s

    2500 masonry units in compression 1000 piles in compression

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    12

    Effectofverticalload

    Meli (1975).

    Horizontalreinforcement

    Alcocer

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    13

    Horizontalreinforcement

    ResearchonMasonry

    Juan Guillermo Arias A (2005) and Sergio Alcocer

    Shaking table test 3 floors, confined masonry building, traditional masonry (crafted masonry units) no horizontal reinforcement

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    14

    Results

    Plastic deformations concentrate in first floorobserved drifts are much lager than those inpseudo-static tests

    Aspectratio

    J J Perez Gavilan E, L E Flores, Alcocer 2013

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    15

    Effectofaspectratio

    Shearmomentinteraction

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    16

    ShearMomentInteraction

    A. Manzano, J J Perez Gavilan E

    My Students 3PhDstudents

    Behaviourofmasonrywallssupportedbyflexibleelements(beams)[experimental,CONACYT]

    Momentshearinteractioninconfinedmasonrywalls[experimentalfinished,CONACYT]

    Behaviourofinfillwallssubjectedtolateralloads[experimentalstarting,UniversityofSinaloa]

    7Mastersstudents Effectofflexiblediaphragms Effectofmomentshearinteractioninmasonrystructures Shearstrengthcontributionofhorizontalreinforcementsinconfinedmasonry

    walls.[experimental,sponsoredbycitygovernment] Nonlinearmodelsforinfillwalls[starting] Detailedmodellingofconfinedmasonrywallswithhorizontalreinforcement Comparisontwodesignsofabuildingusingthecurrentcodeandthenew

    provisions.

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    17

    TypicalMasonryUnits

    Clay Concrete blocks

    Typical masonry buildings

    Urban middle income housing

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    18

    Typical masonry buildings

    Urban middle income housing

    Typical masonry buildings

    Urban middle income housing

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    19

    LowIncomeHousing

    Finalphaseofconstruction

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    ConstructionSite

    Metallic formwork for large sites

    MasonryConstructioninCanada

    Canadaisacountrywitharelativelysmallpopulation(about35million likeMumbaiandDelhicombined)

    Andaverylargearea(around10millionkm) about3timestheareaofIndia

    Theclimateisverycoldinthewinters(upto 50degreesC)andwarminthesummermonths(upto40degreesCincitieslikeToronto)

    Ayoungcountry CanadianConfederationestablishedin1867

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    21

    MasonryinCanada:HeritageBuildings

    No. 41

    Quebec City, Quebec

    No. 42

    MasonryinCanada:HeritageBuildingsMarine Building, Vancouver, 1930s

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    A school building, Vancouver Concrete block masonry walls Concrete brick veneers

    (cladding!) Sustainability benefits: 20% fly

    ash cement replacement

    MasonryinCanada:ModernConstruction

    Modern Masonry Construction - Fire Halls

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    23

    ModernMasonryConstruction

    45

    University of British Columbia, Vancouver

    Use of recycled bricks Sustainable design top priority LEED rating system applied in many

    projects

    No. 46

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    1

    Short Course on Seismic Design of Reinforced and Confined Masonry Buildings

    February 17-21, 2014, IIT Gandhinagar, India

    TopicsMasonry buildings: key componentsLoad pathDesign methodsMasonry design standards

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    2

    MasonryBuildings:KeyComponents

    Verticalstructuralcomponents:masonrywalls Loadbearing resisttheeffectsofgravityloads(includingselfweight)pluslateralloads

    Nonloadbearing resistonlytheeffectsoftheirselfweightandpossiblyoutofplanewindandearthquakeloads

    Horizontalstructuralcomponents(diaphragms) Floorsandroof

    KeyComponents

    Source:Drysdale

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    3

    LoadPath

    Multipleelementsareusedtotransmitandresistexternalloadswithinabuilding.Theseelementsdefinethemechanismofloadtransferinabuildingknownastheloadpath. GravityLoadPath gravityloadonthefloorandroofslabstransferredtothewalls,downtothefoundations,andthentothesupportingsoil.

    LateralLoadPath thewaylateralloads(duetowindorearthquakes)aretransferredthroughabuilding.

    GravityLoadPath

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    4

    GravityLoadPath TributaryArea

    LateralLoadPath:HowLateralForcesFlowThroughaBuilding

    1

    23

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    DesignMethods

    AllowableStressDesign(ASD)Method AlsoknownasWorkingStressDesign

    LimitStatesDesign(LSD)Method UltimateLimitStates(ULS) ServiceabilityLimitStates(SLS)

    AllowableStressDesignMethod Basedontheelastictheory(elasticmaterialbehaviour) Allowablestress=materialstrengthdividedbythefactorofsafety(FOS)

    UsedfordesignofunreinforcedmasonrycomponentsaccordingtoIS:1905(allowablestressesprovidedintabularform)

    LongexperiencewithASDinIndia IthasbeenreplacedbytheLimitStatesDesignapproachbydesigncodesinmanycountries

    Severaldeficiencies:doesnotshowrealstrengthortrueFOS;uneconomicdesign;basedonmodularratio(n)whichisanimaginaryquality

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    6

    AllowableStressDesign(IS1905)LoadCombinations

    Nonearthquakeloadcombinations:1)DL+LL2)DL WL3)DL+LL WL

    Earthquakeloadcombinations:4)0.9DL EL5)DL+LL EL

    LimitStatesDesignMethod

    Thestructureshouldbeabletosafelywithstandexternalloads(strength)anditshouldremainfunctionalduringitslifespan(serviceability) Basicrequirement:Factoredresistance>Factoredloadeffecte.g.Mr >Mf flexuralresistance

    Vr >Vf shearresistance

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    7

    FactoredLoadEffect

    Factoredloadeffect=characteristicloadxloadfactor

    =loadfactor Loadfactorsprescribedforvarioustypesofloadsandloadcombinations LoadfactorsperIS456willbeusedfordesignofmasonrystructuresaccordingtotheLSDmethod

    LimitStatesDesign FactoredResistance

    Basedonthedesignstrength(fd)ofthematerial(e.g.concrete)

    InNorthAmericaandsomeothercountries usematerialresistancefactor

    factorsafetypartialstrengthsticcharacteriff

    m

    ckd __

    _

    m 1

    ckd ff

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    8

    PartialSafetyFactorsforStrength:Concrete,Masonry&Steel

    India Canada India

    Material Partialsafetyfactor forstrengthm

    Materialresistancefactor

    = 1/m = 1/m

    FactorofSafety (FOS)

    ASDMethod

    Concrete 1.5(IS456)

    0.67x0.67=0.45 0.65 3.0

    Masonry 2.0* 0.5 0.60 4.0**

    Steel 1.15(IS456)

    0.87 0.85 1.8

    * proposed(provisionsnotcurrentlyavailableinIndianstandards)

    ** IITKGSDMAGuidelinesforStructuralUseofReinforcedMasonry(2005)

    LimitStatesDesignMethodandThisCourse

    Willbeusedfordesignofreinforcedmasonrywalls,andreinforcedconcretecomponentsinconfinedmasonrybuildings(tiecolumnsandtiebeams) Materialresistancefactors()willbeusedinsteadofpartialsafetyfactors(m)indesigncalculations!

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    9

    LimitStatesDesignMethod LoadFactorsandLoadCombinations

    SameasforRCstructuresperIS456 Nonearthquakeloadcombinations:

    1)1.5DL+1.5LL 2a)1.5DL 1.5WL 2b)0.9DL 1.5WL(overturningorstressreversal) 3)1.2DL+1.2LL 1.2WL

    Earthquakeloadcombinations: 4a)1.5DL 1.5EL 4b)0.9DL 1.5EL(overturningorstressreversal) 5)1.2DL+1.2LL 1.2EL

    MasonryStandards India IS:19051987

    CodeofPracticeforStructuralUseofUnreinforcedMasonry(3rdRevision1961,1969)

    IS:10771986SpecificationsforCommonBurntClayBuildingBricks

    IS:22121962CodeofPracticeforBrickwork

    IS:2185141&142SpecificationsforConcreteMasonryUnits(SolidandHollow)

    IS:39521978SpecificationsforBurntHollowClayBlocks

    IS:33161974SpecificationsforStones(inregularsize)

    IS:22501981CodeofPracticeforPreparationandUseofMasonryMortar

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    InternationalMasonryStandards(1/2) USA(relevantforreinforcedmasonrydesign)TMS40213/ACI53013.BuildingCodeRequirements&SpecificationsforMasonryStructuresandRelatedCommentaries,AmericanConcreteInstitute,FarmingtonHills,MI. Canada(relevantforreinforcedmasonrydesign)CSAS304.104(2004).DesignofMasonryStructures,CanadianStandardsAssociation,Mississauga,Ontario(2014editioncurrentlyunderreview). NewZealand(relevantforreinforcedmasonrydesign)NZS4230:2004DesignofReinforcedConcreteMasonryStructures,StandardsAssociationofNewZealand,Wellington.

    InternationalMasonryStandards(2/2) Europe(relevantforreinforcedandconfinedmasonrydesign)Eurocode6(2006).DesignofMasonryBuildings Part11:CommonRulesforReinforcedandUnreinforcedMasonryStructures,EN19961:2006,CEN,Belgium. Mexico(relevantforconfinedmasonrydesign)NTCM(2004).TechnicalNormsforDesignandConstructionofMasonryStructures(NormasTcnicasComplementariasparaDiseoyConstruccindeEstructurasdeMampostera),MexicoD.F. availableinSpanishandEnglish.

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    11

    Questions?

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    1

    Short Course on Seismic Design of Reinforced and Confined Masonry Buildings

    February 17-21, 2014, IIT Gandhinagar, India

    Durgesh C RaiProfessor

    IIT Kanpur

    Masonry Materials

    Clay BricksClay Bricks

    http://www.brick.com

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    3

    Classification

    Clay Bricks Most Common Two types of

    Un-burnt Burnt

    Clay Chemical composition

    Silica & Alumina

    4

    Clay Brick units

    Raw materials Clay

    Types Surface clays : sedimentary formation Shales : Clays subjected to high pressure until they become slate Fire clay : Deeper sites, refractory like properties

    Iron oxide Hydrated silicates of alumina Miscellaneous impurities (e.g., Ca, Mg, Na, Ti, K) Metallic oxide gives color to fired product

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    5

    Significant physical properties of clays Plasticity Fusibility Tensile strength Shrinkage

    Clay Brick units

    6

    Manufacturing Bricks Winning and storage of raw materials

    Usually mined from open pits Preparation

    Grinding Sieving Pug mills

    Forming Tempering

    To produce homogeneous , plastic mass ready for mouldingMixing water to clays in pug mills

    Clay Brick units

    CE62

    5-Ma

    sonr

    y stru

    cture

    s/Dr D

    urge

    sh R

    ai/IIT

    K/20

    12

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    7

    Manufacturing Bricks Forming

    Three processes Stiff mud process

    12-15% water by weight Pugging and De-airing gives increased strength Forms clay strip through extruder-wire cutter

    Soft mud process 20-30% of water by weightCast in moulds sand struck Lubricated with water

    Dry press process 7-10% of water by weight Steel moulds under pressure of 3.4-10 MPa

    Clay Brick units

    8

    Manufacturing Bricks Drying

    Control temperature & humidity To avoid excessive cracking

    Firing 40-150 hours

    Clays soften slowly and melt and fuse gradually when subjected to rising temeperatures

    This fusibility of clay makes it hars, solid and of low absorbing capacity Fusion stages

    Incipient stage: Soft particle stick together Vitrification stage: Clays form solid, non-absorbent mass (875-1300 C) Viscous stage: Clay mass breaks down and tends to become molten (should avoid

    this stage) Cooling

    Important stage 48-72 hours Rapid cooling will cause cracking

    Clay Brick units

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    9

    Manufacturing Bricks Brick forming machine

    Clay Brick units

    10

    Manufacturing Bricks Firing in Clamps/Scoves

    Clay Brick units

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    11

    Manufacturing Bricks Bulls Trench Kiln

    Continuous

    Clay Brick units

    12

    Manufacturing Bricks Hoffmans Kiln

    Clay Brick units

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    13

    Engineering Properties

    Absorption Related to degree of burning of clay particles, fusing

    temperatures and porosity Durability

    Incipient fusion Partial Vitrification

    Thermal Conductivity Acoustics Fire Resistance

    14

    Compressive strength Properties of clays and methods of manufacture

    Stiff mud process produces bricks of higher compressive strength

    Degree of firing For given clay and method of manufacture, higher firing

    temperature produces bricks of higher strength and lower absorption

    Flexural Strength Factors affecting are same as those for compressive strength

    Elastic Modulus Split Tensile Strength

    Engineering Properties

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    15

    Physical Properties

    Colour Iron oxide content controls, but depends on

    Oxidizing (red) or reducing (purple) environs

    Texture Smooth or sand finished

    Form and size variation Air 2-8% Fire 2.5-10%

    Dimensional stability

    16

    Water Absorption

    Total Water Absorption =Weight of water absorbed after 24 hrs in cold water

    Total dry weight

    (a) Saturation Coefficient C/B Ratio =Weight of water absorbed after 24 hrs in cold water .Total absorption after 5hr boiling + 24 hr in cold water

    C/B ratio is measure of freeze-thaw durability and should not be greater than 0.78.

    Secondary pores filled by boiling water

    Primary pores filled by cold water

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    17

    Water Absorption and Initial Rate of Absorption- Gives information about quality of bricks

    fbWA IRA

    WA: Water Absorption capacity of the brick material

    IRA: Suction of water from mortar due to capillary action in bricks (per minute, per unit area, brick immersed in about 3 mm deep water)

    Water Absorption

    18

    (b) Initial Rate of AbsorptionIRA = (W1-W)/Anet

    W1=Weight of brick after 1 min in 1/8 (3 mm) water W= Dry weight of the brick

    IRA < 30g/min/30in2 Usually IRA is 5.0-40.0g/min/30in2 (0.25-2.05 kg/min/m2) IRA < 0.25 kg/min/m2

    Bricks may float on mortar, if the brick is damp Low Absorption-Low suction Units

    IRA > 1.5 kg/min/m2Highly absorptive Poor bond if dry thin layer of mortar is kept next to it Should be wet before (3-24 hrs),

    but surface is dry when laid with mortar

    Water Absorption

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    19

    (b) Initial Rate of Absorption High IRA is undesirable because of

    Rapid drying of mortar Poor bond strength between brick and mortar Poor non-structural performance

    due to water penetration into masonrySoaking of units is desired if IRA > 1.5 kg/min/m2

    Water Absorption

    20

    Engineering Properties

    Compressive Strength Depends on

    Clays Type of manufacturing process Degree of burning

    Tested Flat-wise (ASTM C67)fb = P/Anet

    If Anet>Agross (75%), then use Anet = Agross Since core will add strength because of

    Uniform drying and Shrinkage Bond action between mortar and brick

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    21

    Compressive Strength North American bricks

    3-30ksi (21-210 MPa) Nominal Strength (8-15ksi) (56-105 MPa)

    Indian Bricks > 3.5 MPa 10-20 MPa common for bricks in North India

    Engineering Properties

    22

    Modulus of ElasticityEb=1400-5000 ksi (9.8-35.0 GPa)

    Modulus of Rupture fr =1.5 Pl/bt2

    Sahlin: fr /fb varies ~0.1-0.32

    Coefficient of Thermal Expansion0.0045-0.0072 mm/m/C(Fire clays Shale Surface clays)

    Engineering Properties

    l

    t

    b

    P

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    23

    Tensile Strength of Brick Units

    Split tensile strength, ft (ASTM C 1006-07) Flat position On edge position

    L

    Split tensile failure

    Alignment Jig

    Flat Position On Edge Position

    2t

    PfLH

    P

    P

    H

    24

    Tests on Bricks

    Flowchart Dry Bricks in oven for 24 hours Weigh dry bricks (determine density) Run IRA Dry Bricks Run Modulus of Rupture Test Run Absorption Test

    Soak in cold water for 24 hours Run Saturation Coefficient Test (optional)

    Soak half-bricks in boiling water 5 hours Run flat-wise Compressive Test (Cap and crush)

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    25

    IS 1077: Bricks

    Class of bricks Based on compressive strength

    26

    IS 1077: Bricks

    Dimension of bricks

    Common brick size Approx. 23511070 mm (94.52.75 in.)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    27

    IS 1077: Bricks

    Water Absorption

    28

    Compressive Stress-Strain Curves of Brick Units-Research at IIT Kanpur (Kaushik et al 2007)

    Four brick manufacturers: M: MBFB: BajrangO: OnkarS: Sarang

    Average Dimensions:Length 230 mmWidth 110 mmHeight 75 mm

    Compressive Behaviour Clay Bricks

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    Typical crushing failure

    Test Setup

    Compressive Behaviour Clay Bricks

    30

    Brick type fb (MPa) Failure strain Eb (MPa)M (10 specimens) 17.7 [0.23] 0.0072 [0.18] 5300 [0.15]B (10 specimens) 16.1 [0.08] 0.0060 [0.19] 5030 [0.34]O (10 specimens) 28.9 [0.23] 0.0070 [0.39] 7516 [0.26]S (10 specimens) 20.6 [0.17] 0.0057 [0.28] 6534 [0.10]

    Avg (40 specimens) 20.8 [0.33] 0.0065 [0.34] 6095 [0.29]

    [] COV

    0

    5

    10

    15

    20

    25

    30

    0.000 0.002 0.004 0.006 0.008 0.010 0.012Strain

    Com

    pres

    sive

    Stre

    ss, M

    Pa

    MB

    O

    SAverage

    bb

    bb

    bb

    bb

    bb

    fEfEfEfEfE

    300317S260O312B300M

    Eb - slope between0.05fb - 0.33fb

    Compressive Behaviour Clay Bricks

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    Eb 150fb to 500fbVariation of fb with Eb

    Cr Correlation Coefficient (Poor Cr for Eb 300fb )

    0

    2000

    4000

    6000

    8000

    10000

    12000

    0 10 20 30 40Brick compressive strength, MPa

    Bric

    k el

    astic

    mod

    ulus

    , MPa M bricks

    B bricks

    O bricks

    S bricks

    40 brick specimens

    C r =0.39

    bb fE 300

    bb fE 150

    bb fE 500

    Compressive Behaviour Clay Bricks

    32

    IRA and fb are more closely correlated

    Too low IRA, bricks may float on mortarToo high IRA, rapid suction of water in mortar by bricks Poor Brick-Mortar Bond

    IRA test is not mandatory as per IS:3495 (1992)

    Compressive Behaviour Clay Bricks

    0

    10

    20

    30

    40

    0 1 2 3IRA, kg/m2/min

    Com

    p. st

    ress

    , MPa

    C r = - 0.77

    8 10 12 14 16WA, %

    C r = - 0.24

    IRA vs. WA

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    33

    Fly Ash BricksFly Ash Bricks

    34

    Fly Ash BricksAdvantages Higher cold crushing strength (10-15 MPa) Low water absorption (13-15%)

    Reduced efflorescence Smooth and uniform size

    Requires less quantity of cement mortar & no plaster

    Lower bulk density (1600 kg/m3) Reduces dead weight

    on load bearing walls Saves transportation cost

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    35

    Methods of Manufacturing

    Primary Ingredients Fly ash (Grade 1 or 2 of IS 3812) Sand Lime (Hydraulic Class C of IS 712) Chemical accelerators, small quantity such as

    Gypsum, cement, etc. Mixing

    In the first stage, only dry mixing is done About 8- 10% water, 0.2% (by weight) chemical

    accelerator is added in the second stage mixing. This admixture is further subjected to thorough

    mixing in the third stage.

    36

    Methods of Manufacturing

    Moulding Fly ash is a non-plastic material

    Raw mix is subjected to a pressure of ~25 MPa in a suitable hydraulic press

    Double acting brick press (Cybertek Engineering, Faridabad)

    Brick Press (CBRI, Roorkee)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    37

    Methods of Manufacturing

    Drying Green bricks exposed to natural drying

    for about 48-60 hours Depending upon weather conditions

    Steam Curing Semi- dried bricks cured in Autoclaves

    (steam chamber) at a desired pressure & temperature Steam cured finished bricks stacked in open

    They gain further strength

    38

    Specifications

    IS 12894-2002 Dimensions same as clay bricks Compressive Strength

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    39

    Specifications

    IS 12894-2002 Water Absorption

    Efflorescence

    40

    AAC BlocksAAC Blocks

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    41

    Autoclaved Aerated Concrete

    DEPARTMENT OF CIVIL ENGINEERING, IIT KANPUR

    AAC Blocks(Fortune EkoTech)

    Cellular structure of AAC(Tanner, 2003)

    41

    Light-weight cementitious material with closed cellular structure Low strength and stiffness compared to conventional masonry Easily cut into any shape with hand tools Good fire, thermal and acoustic resistance

    42

    Concrete Masonry Units Manufacturing

    Developed by Swedish architect Johan Axel Eriksson in 1900s AAC is a mixture of cement, sand, lime, gypsum and

    aluminium powder which is steam cured Aluminum powder reacts with calcium hydroxide and water

    to form hydrogen, which increases the volume by two to three times.

    At the end of the foaming process, the hydrogen escapes into the atmosphere and is replaced by air.

    Finally, the blocks are cured in an autoclave, producing a final material, with about one-fifth to one-third the density of structural concrete.

    Can be cut and nailed like wood and good thermal insulation and fire resistance of concrete

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Concrete Masonry Units Manufacturing

    PropertiesClay Fly-Ash AAC

    blockA B A B

    Density (kg/m3) 1774.0 1740.0 1520.0 1600.0 709Water Absorption (%) 13.4 15.0 24.4 25.4 321.7Saturation Coefficient - 0.82 0.91 0.88 0.58IRA (kg/m2/min) 2.7 4.4 4.4 1.6 2.7Compressive Strength (MPa) 21.9 5.4 5.3 9.1 2.4

    Tensile Strength (MPa)

    Flat position 1.0 0.3 0.4 0.40.4

    On edge 1.7 0.5 0.5 0.7

    Comparison of Conventional Units and AAC Blocks

    Tests conducted at IIT Kanpur (2012)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Concrete BlocksConcrete Blocks

    46

    Concrete Masonry Units

    Dimensions BHL Specified dimension 3/8 < Nominal dimension Actual dimension within 1/8 (3mm) of

    Specified dimension Example

    Nominal Dimension: 200200400 mm Specified Dimension: 190190390 mm

    Tapered holes, top-thicker web for better mortar placement and ease of lifting out of moulds

    L

    H

    B

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    47No. 47

    Concrete Masonry Units

    48

    Concrete BlocksPhysical Requirements

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    49

    Concrete Masonry Units

    IS 2185 (Part 1):2005

    50

    Concrete Masonry Units

    IS 2185 (Part 1):2005

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    51

    RAW MATERIALS

    Constituents Portland Cement Pozzolanas

    Reduce expansive characteristic Add surface resistance

    Other Admixtures Air entrainment, pigments, water repellants,

    Aggregates Normal Weight

    >125 pcf (2000 kg/m3) Light Weight

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    53

    Moulding Feed to mould Consolidated by vibration (feed time) Press mix into mould Second vibration cycle consolidates mix (finish time)

    Ejection Come out in a set of 3 supported on steel pallets

    Bottom of mold cavities Put in kiln for 6-8 hrs

    METHODS OF MANUFACTURING

    54

    Curing Done under saturated conditions Elevate temperature for accelerated hydration Store outside for continued curing

    METHODS OF MANUFACTURING

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    55

    METHODS OF MANUFACTURING

    Production Plant

    http://www.besser.com

    56

    Engineering Properties Absorption

    Weight changes after 24hr immersion in cold water 200350 kg/m3

    Total Linear shrinkage Up to 0.065% for Type I Units

    Moisture Content 25-45%

    Compressive Strength 14-42 MPa (lower values in India!)

    Tensile Strength 1.75-3.50 MPa

    Deformational Properties Em=750 fm ; Gm=0.4Em; m=0.28

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    57

    Physical Requirements

    IS 2185 (Part 1) :2005 Concrete BlocksType Grade Density of

    Block(kg/m3)

    Minimum Compressive Strength (MPa)

    Minimum Compressive Strength of individual units (MPa)

    Hollow load bearing unit(Open & closed cavities)

    A(3.5) Not less than 1500

    3.5 2.8

    A(4.5) 4.5 3.6A(5.5) 5.5 4.4A(7.0) 7.0 5.6A(8.5) 8.5 7.0

    A(10.0) 10.0 8.0A(12.5) 12.5 10.0A(15.0) 15.0 12.0

    58

    IS Concrete BlocksPhysical Requirements

    Type Grade Density of Block(kg/m3)

    Minimum Compressive Strength (MPa)

    Minimum Compressive Strength of individual units (MPa)

    Hollow non-load bearing unit (open & closed cavity)

    B (3.5) Less than 1500 but not

    less than 1100

    3.5 2.8B(5.0) 5.0 4.0

    Solid Load bearing units

    C(5.0) Not less than 1800

    5.0 4.0C(4.0) 4.0 3.2

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    59

    Concrete Blocks MachinesPhysical Requirements

    60

    Concrete Blocks Machines Besser Machine in India in 1950s Sindhu Resettlement Corporation Gandhidham city 2001 Bhuj Earthquake

    Physical Requirements

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    31

    Mortars for Masonry

    Mortars for Masonry

    62

    Basics

    Mortar integrates a masonry wall Bonding agent Major properties

    Strong, durable, capable of keeping wall intact, create water resistant barrier

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    63

    Good concrete practice does not mean good mortar practice It differs in

    Working consistenciesWater-Cement ratio

    Methods of placement Between absorbent masonry units

    Structural performance High Water-Cement ratio at beginning decreases strength

    Basics

    64

    Historical Masonry Early mortars to fill voids between stones First mortars were mud and tar Early mortars lime + sand Early admixtures

    Egg whites, clays, urine, oxblood, jaggery, syrups

    Basics

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    65

    Constituents of Mortars

    Cements Portland cement

    Contributes to durability, high strength and early setting of mortar

    Masonry cement Proprietary mortar mixes for good workability Portland cement + ground limestone as filler (55:45) Additives for workability and water retentivity and

    air entrainment

    66

    Limes Contributes to bond, workability, water retentivity &

    elasticity Hydrated lime (Calcium hydroxide :: Ca(OH)2)

    Derivative of Lime Stone - Preferred Quick Lime (Calcium Oxide :: CaO)

    Not Common IS: 1905 Three types of Lime

    A : Hydraulic lime B : Semi-hydraulic lime C : Fat Lime

    Constituents of Mortars

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    67

    Limes Hardens only upon contact with CO2 in the air

    Occurs slowly over a period of time Autogenous Healing

    If small hairline cracks develop, water and CO2which penetrate the joint will form CaCO3 and newly developed CaCO3 will seal the cracks and prevent further water ingression.

    Constituents of Mortars

    68

    Role of Lime

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    69

    Role of Lime

    70

    Role of Lime

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    71

    Aggregates Natural sand

    From rivers Manufactured

    Act as a filler Give an economical mix Control shrinkage

    Constituents of Mortars

    72

    Aggregates Grading (gradation) can be altered for specific use

    IS: 1905Well graded sand required

    If not, reduce proportion to achieve minimum compressive strength

    ASTM C144 Sieve Analysis No. 4 (4.75 mm) : 100% No. 8 (2.36 mm) : 95-100% No.16 (1.18 mm) : 60100 No.30 (600 m) : 35-70% No.50 (300 m) : 1535% No.100 (150 m) : 215% No.200 (75 m) : 02%

    Constituents of Mortars

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    73

    Water Clean Free of acids, alkalis & organic materials

    Admixtures Usually not used

    Constituents of Mortars

    74

    Mortar Proportions

    ASTM C270 and US PracticeM a S o N w O r K

    Strongest Weakest ASTM

    4 Types of Mortars, M, S, N, O

    Proportions by volume Aggregate Ratio

    Measured in loose/dump conditions

    2.25 and 3.5 times sum of separate volumes

    Grade Cement Lime

    M 1 1/4

    S 1 Over 1/4 to 1/2

    N 1 Over 1/2 to 5/4O 1 Over 5/4 to 5/2

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    75

    Common Mix ProportionsMortar Proportions

    Grade Cement Lime Sand Air Content

    Average Compressive

    Strength (MPa)

    % water

    M 1 1/4 3 12% 17.2 0.75S 1 1/2 4 12% 12.4 0.75

    N 1 1 6 14% (12%) 5.2 0.75

    O 1 2 9 14% (12%) 2.4 0.75

    Sum of binder (cement +lime) equals 1/3 of sand volume (assuming that sand has void ratio of 1 in 3)

    76

    IS:1905:1987, Table 1 Three grades

    High (H), Medium (M) & Lean (L) Strength Mortars

    Mortar Proportions

    Grades Cement Lime Sand ASTM 28-day compressive strength (MPa)

    H1 1 ( C or B) 3 M 10.0H2 1 ( C or B) 4 S 7.5

    1 ( C or B) 4 6.0M1 1 1 ( C or B) 5 N 5.0

    1 6 3.0M2 1 2 (B) 6 3.0

    1 1 (A) 9 2.0 1 (C or B) 2 2.0

    M3 1 3 (B) 7 O 1.5 1 1 (A) 12 1.5

    1 (C or B) 3 1.5

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    39

    77

    Polymer modified mortars

    Thin bed joints 2 to 3 mm thick Typically used with AAC blocks Higher water retentivity for improved bond

    characteristics

    78

    Physical Properties

    Two distinct sets In plastic state

    Compatibility and construction suitability In hardened state

    Performance of finished Masonry (Flexural) Bond Strength Durability Extensibility Compressive Strength Workability Water retentivity Initial Flow Flow after suction

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    40

    79

    Workability Workable if

    consistency allows it to be spread easily adheres to vertical masonry surfaces

    Masons are best judges!! No laboratory test

    Factors affecting Water retentivity Flow Resistance to segregation effect

    Physical Properties

    80

    Durability Not a problem for unsaturated masonry

    Water Content Most misunderstood aspect of masonry Many specifications incorrectly require

    minimum water content consistent with workability Maximum water consistent with workability provides

    maximum bond strength within the capacity of the mortar Re-tempering to compensate water lost by evaporation

    Allowed within 2.5 hours after mixing on board

    Physical Properties

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    41

    81

    Extensibility & Plastic Flow Extensibility

    Maximum tensile strain at failure Plastic Flow

    High lime mortars exhibit greater plastic flow Plastic flow or creep with extensibility imparts

    flexibility to masonry permitting slight movement Where greater resiliency is required, lime content is

    increased while satisfying other requirements

    Physical Properties

    82

    Initial Flow and Water Retentivity Initial flow a measure of mortars water-cement ratio Water retention is ability to hold water

    when in contact with absorbent units To increase water retention

    Add sand fines within allowable gradation limits Use high plastic lime mortar (Type S) Increase air content should not be greater 12%

    ASTM C109, C110 and C230

    Physical Properties

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    42

    83

    Initial Flow and Water Retentivity Too much water will result in mortar too fluid to support

    weight of a few courses Good water retention is important

    To keep water from bleeding out of mortar To prevent mortar from stiffening before units are laid To ensure proper hydration of cement

    Desirable to have consistent IRA of unit and water retentivity of mortar

    Low IRA with low water retentivity or high IRA with high water retentivity

    Physical Properties

    84

    Initial Flow and Water Retentivity Physical Properties

    If water migrates too quickly from mortar to unit, cement may not hydrate fully resulting in reduced bond strength

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    43

    85

    Brick-Mortar interfacephysical properties

    86

    Higher Flexural Bond strength Roughened Surface

    IRA

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    44

    87

    Compressive Strength

    Depends on Cement content of mortar Water-Cement ratio

    Less important than Bond strength Workability Water retentivity

    88

    Test Methods 50 mm cubes 50 mm diameter, 76 mm long cylinders Consistent results

    Can be used for comparing mortars

    Durability Not a problem in unsaturated masonry

    Compressive Strength of Mortar

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    45

    89

    Influencing factors Proportions

    Increases with cement content Decreases with lime content & over-sanding

    Re-tempering Re-tempering decreases compressive strength But this reduction is less,

    if it is done within 2 hrs after mixing

    Compressive Strength of Mortar

    90

    Compressive Stress-Strain Behaviour of MortarResearch at IIT Kanpur (Kaushik et al. 2007)

    Three grades of mortar used:[Cement : Lime : Sand]

    1:0:6 (Weak) 1::4 (Intermediate) 1:0:3 (Strong)

    Water-Cement ratio: 0.75

    Compressive Behaviour of Mortar

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    46

    91

    Typical Crushing Failure

    Compressive Behaviour of Mortar

    92

    fj (MPa) Failure strain Ej (MPa)Weak mortar 1:0:6 (9 specimens)

    3.1 [0.22] 0.0087 [0.38] 545 [0.30]Strong mortar 1:0:3 (9 specimens)

    20.6 [0.08] 0.0185 [0.21] 3750 [0.16]Intermediate mortar 1:0.5:4.5 (9 specimens)

    15.2 [0.06] 0.0270 [0.36] 3300 [0.26]

    0369

    12151821

    0.000 0.005 0.010 0.015 0.020 0.025 0.030

    Strain

    Com

    pres

    sive

    Stre

    ss, M

    Pa

    1:0.5:4.5 mortar

    1:0:6 mortar

    1:0:3 mortar

    jj

    jj

    jj

    jj

    fEfEfEfE

    2002154.5:0.5:11803:0:1175 6:0:1

    Compressive Behaviour of Mortar

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    47

    93

    Lime mortar (Intermediate) performed well in terms of both strength and ductility

    Intermediatemortar

    Strongmortar

    ~ 35% less

    ~ 45% more

    Failure Strain

    Comp. Strength

    Lime in mortar beneficial mandatory in several international codes (but not in Indian Code)

    Compressive behaviour of mortar

    94

    Variation of fj with Ej

    0

    1000

    2000

    3000

    4000

    5000

    0 5 10 15 20 25Mortar compressive strength, MPa

    Mor

    tar e

    lasti

    c m

    odul

    us, M

    Pa 1:0:6 mortar1:0.5:4.5 mortar1:0:3 mortar

    27 mortar cube specimens

    C r =0.90

    jj fE 200jj fE 400

    jj fE 100

    Ej 100fj to 400fj

    Cr Correlation Coefficient (Good Cr for Ej 200fj )

    Compressive behaviour of mortar

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    48

    95

    Selection of Mortar

    Basics Function of needs of the finished structural element

    Stronger is better could not be farther from the truth for mortar

    96

    Two competing properties Bonding agent which must be

    Strong Capable of keeping wall intact Must create water-resistant barrier Contain certain resilient properties, and Easy to use by mason

    Huge compressive strength is of no use, if It does not bond well It cannot be laid properly & easily by masons

    Selection of Mortar

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    49

    97

    Two competing properties Neither is acceptable,

    if the mortar has high cement content High compressive strength & shrinkage characteristics

    will cause separation cracking between mortar & unit Results in wind driven rain penetration of wall

    elements

    Selection of Mortar

    98

    Basic Rule No single type of mortar is best for all purposes Never use a mortar stronger than

    that is required by structural requirement Always select weakest mortar than

    that is consistent with the performance requirements of the project

    Selection of Mortar

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    50

    99

    Recommendations for general usesSelection of Mortar

    ASTM Location Building Segment

    Mortar Type Recommended

    Alternative

    ExteriorAbove grade

    Load-bearingNon-load bearingParapet Walls

    NNN

    S or MO or S

    SExterior Below grade

    Foundation walls,Retaining walls, manholes, sewers

    M S

    Interior Load bearing Partitions

    NO

    O, S, MN or S

    100

    General Properties Type N Mortar (1 : 2 : 6)

    Exterior walls subjected to excessive exposure, chimneys, parapets

    Medium strength suitable for exposed masonry above grade

    Selection of Mortar

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    51

    101

    General Properties Type S Mortar (1 : : 4 )

    For RM and URMWhere maximum flexural bond strength is requiredWhere mortar adhesion is sole bonding agent between facing &

    backing Reasonably high compressive strength & high tensile

    strength with most units

    Selection of Mortar

    102

    General Properties Type M Mortar (1 : : 3 )

    For RM & URM below grade in contact with earth High compressive strength & excellent durability

    Type O Mortar (1 : 2 : 9 ) Interior load-bearing/ non-load bearing walls in no

    contact with water

    Selection of Mortar

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    52

    GroutGrout

    104

    Grout

    Purpose To fill voids and cover for rebars

    Grout properties affect development length

    Constituents Portland cement Fine aggregate

    Sand Coarse aggregate

    Pea gravel:: 10mm max Lime

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    53

    105

    Composition Mortars with high slump shall not be used as grout Mixture should flow without segregation Lime is rarely used in grouts

    Especially when they are ready mixed

    Cement : Sand : Pea gravel : Lime

    Fine Grout :: 1 : 2-3 : 0 : 0-0.1Coarse Grout :: 1 : 2-3 : 1-2 : 0-0.1

    Grout

    106

    Water content Mortars with high slump shall not be used as grout

    Slump varies from 200-275 mm

    Grout

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    54

    107

    Test for compressive strength

    ASTM 1019 and UBC 24-22 Form work made from the units used for masonry

    To simulate moisture absorption as in reality Wrap with paper towel, for easy removal of the

    specimen

    108

    Test for compressive strength

    ASTM 1019 and UBC 24-22 For concrete blocks

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    55

    109

    Mortar and Grout Testing

    [Brzev, BCIT]

    110

    Grout placement methods

    Two types Low lift

    Placed and consolidated as masonry is constructed Low slump values Max. height = 1.5 m

    High lift Placed after a story is constructed Vibration needed

    CE62

    5-Ma

    sonr

    y stru

    cture

    s/Dr D

    urge

    sh R

    ai/IIT

    K/20

    12

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    56

    Reinforcement inMasonry

    Reinforcement inMasonry

    112/CE625-Masonry Structures-IITK-DCRai

    Reinforced Masonry

    Historical Perspective

    5. BREBNER, A. Notes on Reinforced Brickwork. Technical Paper No. 38, Volumes 1 and 2. Calcutta, Public Works Department, Government of India, 1923.

    In the 1920s a great deal of reinforced brickwork was built in Bihar and orissa in India which was reported by Sir Alexandar Brebner[5]. Figure 6 shows a beam being subjected to a live load, whilst Figure 7 shows an attractive application.

    ROBERTS, J. J., EDGELL, G. J. and RATHBONE, A. J. (1986). HANDBOOK TO BS 5628: PART2 Structural use of reinforced and prestressed masonry, Viewpoint Publications, UK

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    57

    113/CE625-Masonry Structures-IITK-DCRai

    Reinforced Masonry

    Historical PerspectiveIn the 1920s a great deal of reinforced brickwork was built in Bihar and orissa in India which was reported by Sir Alexandar Brebner[5]. Figure 6 shows a beam being subjected to a live load, whilst Figure 7 shows an attractive application.

    ROBERTS, J. J., EDGELL, G. J. and RATHBONE, A. J. (1986). HANDBOOK TO BS 5628: PART2 Structural use of reinforced and prestressed masonry, Viewpoint Publications, UK

    114/CE625-Masonry Structures-IITK-DCRai

    Reinforced Masonry

    Historical Perspective

    6. LORD BAKER OF WINDRUSH. Enterprise vs Beaurocracy. The development of structural air raid precautions during the Second World War. Pergamon Press, 1978.

    At Quetta reinforced brickwork was built in a special bond (Quetta bond), as shown in Figure 8, to increase resistance to seismic loads. This same technique was considered in the UK during the Second World War for the construction of air raid shelters[6].

    ROBERTS, J. J., EDGELL, G. J. and RATHBONE, A. J. (1986). HANDBOOK TO BS 5628: PART2 Structural use of reinforced and prestressed masonry, Viewpoint Publications, UK

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    58

    115/CE625-Masonry Structures-IITK-DCRai

    Structural Masonry Code IS 2213 : 1991 (2005)

    Brick Works Code of Practice

    Sec. 11.8 for Reinforced Brickwork Bed-joint reinf. every 3-4 course in -bk walls Detailing guidelines such as

    rebar dia. not less than 8 mm wall thick not less than 100 mm brick strength not less than 7.5 MPa Cement : sand mortar of 1:4 mix, no lime Cover in direction of joint not less than 15 mm Mortar between reinf. and brick not less than 5 mm

    No structural design provisions

    116

    Steel Reinforcement

    Reinforcement Bars Mild Steel Bars Deformed bars Conforming to IS 1786

    Joint reinforcements Cold-drawn wire for cement concrete reinforcement

    CE62

    5-Ma

    sonr

    y stru

    cture

    s/Dr D

    urge

    sh R

    ai/IIT

    K/20

    12

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    59

    117/CE625-Masonry Structures-IITK-DCRai

    Reinforcement Placement

    Reinforcement shall be located Such that it acts compositely with the masonry

    Perforated clay bricks & Hollow blocks Perforated clay bricks & Hollow blocks Bed joint reinforcement Bed joint reinforcement

    Grout/concrete

    118/CE625-Masonry Structures-IITK-DCRai

    Reinforcement shall be located Such that it acts compositely with the masonry

    Reinforcement Placement

    Quetta Bond Pockets to receive rebars

    Quetta Bond Pockets to receive rebars

    Joint reinforcement to Connect multi-wythe walls

    Joint reinforcement to Connect multi-wythe walls

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    60

    119/CE625-Masonry Structures-IITK-DCRai

    Reinforcement shall be located Such that it acts compositely with the masonry

    Reinforcement Placement

    Reinforcement placed in the bed joints of grooved UnitsReinforcement placed in the bed joints of grooved Units

    Concrete filledcavity wall

    Concrete filledcavity wall

    Reinforced hollowblockwork wall

    Reinforced hollowblockwork wall

    120/CE625-Masonry Structures-IITK-DCRai

    Reinforcement shall be located Such that it acts compositely with the masonry

    Reinforcement Placement

    [McKenzie 2001]

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    61

    Indian Standards on Masonry

    Indian Standards on Masonry

    122

    Indian Standards Masonry related

    IS:1905-1987 Code of Practice for Structural Use of Unreinforced Masonry

    IS:1077-1986 Specifications for Common Burnt Clay Building Bricks

    IS:2212-1962 Code of Practice for Brickwork

    IS:2185 (Part 1)-2005 Specifications for Concrete Masonry Units (Solid and Hollow)

    IS:3952-1978 Specifications for Burnt Hollow Clay Blocks

    IS:3316-1974 Specifications for Stones (in regular size)

    IS:2250-1981 Code of Practice for Preparation and Use of Masonry Mortar

    IS:12894-2002 Specifications for Pulverized Fuel Ash-Lime Bricks

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    1

    Short Course on Seismic Design of Reinforced and Confined Masonry Buildings

    February 17-21, 2014, IIT Gandhinagar, India

    Durgesh C RaiProfessor

    IIT Kanpur

    Mechanical Properties of Masonry

    Characterization of Characterization of Masonry

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    2

    Masonry Characterization: Brick Assemblages

    Tests conducted on assemblages

    Masonry Properties

    Compressive strength Stack bonded

    prismElastic modulus

    Bond strength Tension bond test

    Flexural strength

    Parallel to bed joint

    Perpendicular to bed joint

    Masonry Characterization: Brick Assemblages

    Tests conducted on assemblages

    Masonry Properties

    Shear strength

    One-brick triplet Two-brick triplet

    Diagonal tensile strength

    Half-brick thick Full-brick thick

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    3

    Mechanics of Masonry Mechanics of Masonry in Compression

    6

    Typical failure modesCompressive Behaviour

    Masonry PrismMasonry PrismBrick UnitBrick Unit Mortar CubeMortar Cube

    Uniaxial state of stress Uniaxial state of stress Triaxial state of stress Triaxial state of stress

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    4

    7

    Mechanics of compression

    Masonry Prism

    Masonry PrismMasonry Prism

    Triaxial state of stress at the interface of brick and mortar in masonry prism, brick subjected to net tension

    Triaxial state of stress at the interface of brick and mortar in masonry prism, brick subjected to net tension

    Brick UnitBrick Unit Mortar CubeMortar Cube

    8

    Mechanics of compression

    State of stress

    Masonry PrismMasonry Prism

    Triaxial state of stress at the interface of brick and mortar in masonry prism, brick subjected to net tension

    Triaxial state of stress at the interface of brick and mortar in masonry prism, brick subjected to net tension

    Brick UnitBrick Unit

    Mortar CubeMortar Cube

    xbxb

    y=P/A

    y

    zb

    zbtbtj y

    yzj

    zjxjxj

    Stresses shown forj b

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    5

    9

    Mechanics of compression

    Bi-axial Strength of Units

    Com

    pressionC

    ompression

    Flat-wise compressive strength of unit from testFlat-wise compressive strength of unit from testfb

    fbdt

    fbDirect-tensile strength of unit from testDirect-tensile strength of unit from test

    fbdt

    fb

    fbdt

    y

    TensionTensionxb

    ''1y

    xb bdtb

    ff

    Brick splits when:

    10

    Mechanics of compression

    Bi-axial Strength of MortarUni-axial compressive strength from testUni-axial compressive strength from test

    Multi-axial compressive strength from testMulti-axial compressive strength from test

    fj

    fj

    y

    xj

    y

    xj

    Com

    pres

    sion

    Com

    pres

    sion

    1fj

    y

    CompressionCompression xj

    '

    4 .1y j

    x j

    f

    Mortar splits when:

    4.1

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    6

    11

    Mechanics of compression

    Masonry Compressive Strength Equilibrium relation

    If mortar crushes

    If brick splits

    '

    4.1y j

    xj

    f

    tb

    tj

    ''1y

    xb bdtb

    ff

    ( ) ( ) jxb b xj j xb xjb

    tt l t l

    t

    '

    '( );4.1 4.1

    y j j bxb j b y j

    f t tt t f

    12

    Compressive Strength

    Masonry Compressive Strength If mortar crushes and brick splits

    simultaneously

    Prism Strength

    Uu is coefficient of non-uniformity (typical range 1.1 to 2.5)

    ' ym

    u

    fU

    tbtj

    ' ''

    ' 'bdt j

    y bbdt b

    f ff

    f f

    ' ''1 ( )y

    xb bdt y jb

    f ff

    Hilsdorf EquationHilsdorf Equation

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    7

    13

    Mechanics of compression

    Non-linear Behaviour of Mortar

    Tri-axial testTri-axial test

    yxj

    y

    xj

    y

    0.2 MPa zj xj

    zj zj

    7 MPa zj xj

    y

    xz

    0.2 MPa zj xj

    7 MPa zj xj

    14

    Mechanics of compression

    Unit Splitting vs. Mortar Crushing Linear Mortar

    CompressionCompression xjTensionTensionxb

    fb

    fbdt

    y

    fj Mortar crushes

    Unit stress path Mortar stress path

    FailureFailure

    Mortar Failure EnvelopeUnitFailure

    Envelope

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    8

    15

    Mechanics of compression

    Unit Splitting vs. Mortar Crushing Non-Linear Mortar

    CompressionCompression xjTensionTensionxb

    fb

    fbdt

    y

    fj

    Unit stress path

    Mortar stress path

    Failu

    re

    Mortar Failure Envelope

    UnitFailure Envelope

    Brick splits

    16

    Effect of Mortar on Compression Weaker Mortar

    Weaker mortar result in low fmRatio j b is larger

    Weaker mortar is more nonlinear

    Compressive Strength of Masonry

    MS

    NO

    fm

    Strain

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    9

    17

    Effect of Mortar on Compression Stronger Mortar

    May not adhere to units well A larger scatter of experimental data Create a stiffer masonry prism which is more

    sensitive to alignment problems during testing and more brittle

    More variable compressive strength

    Compressive Strength of Masonry

    MSNO

    fm

    Strain

    18

    Compressive Strength of MASONRY

    Influencing factors Units

    In general, increases with compressive strength of unit

    Tensile strength & geometry play an important role

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    10

    19

    Influencing factors Mortar

    Low strength mortars result in low prism strengthNonlinear behaviour of mortar and its low stiffness (low Poisson's

    ratio) Subjects units to tensile stresses Reduces compressive strength of masonry from compressive

    strength of unitLarge scatter of data with stronger mortars Stiffer mortar do not adhere & sensitive to alignment

    Thickness of mortar with respect to thickness of unit Prism compressive strength increases with increase in

    brick height/mortar thickness (tb/tj)

    Compressive Strength of Masonry

    yCompressive strength

    of Masonry

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    21

    Table 10 (Draft IS:1905) provides Basic Compressive Strength for masonry based on Crushing strengths of Brick and Mortar

    Code values much lower than observed prism strength Because they correspond to lowest results for units & mortar allowed

    (lower-bound values )

    Compressive Strength of Masonry

    S.No. Mortar Basic Compressive Strength (MPa) of Masonrycorresponding to masonry units whose height-to-width ratio does not exceed 0.75 and

    crushing strength (in MPa) is not less than the values given below

    3.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 25.0 30.0 35.0 40.01 H1 0.35 0.50 0.75 1.00 1.16 1.31 1.45 1.59 1.91 2.21 2.50 3.052 H2 0.35 0.50 0.74 0.96 1.09 1.19 1.30 1.41 1.62 1.85 2.10 2.503 M1 0.35 0.50 0.74 0.96 1.06 1.13 1.20 1.27 1.47 1.69 1.90 2.204 M2 0.35 0.44 0.59 0.81 0.94 1.03 1.10 1.17 1.34 1.51 1.65 1.905 M3 0.25 0.41 0.56 0.75 0.87 0.95 1.02 1.10 1.25 1.41 1.55 1.786 L1 0.25 0.36 0.53 0.67 0.76 0.83 0.90 0.97 1.11 1.26 1.40 1.067 L2 0.25 0.31 0.42 0.53 0.58 0.61 0.65 0.69 0.73 0.78 0.85 0.95

    22

    Masonry Prism strength

    Basic Compressive Strength, fm 5-brick/block prism test

    Appendix B of IS:1905 fm=P/Anet

    Correction for different aspect ratios of prism for h/t in the range of 2 and 5

    Table 15: Correction Factors for Different h/t Ratios

    (Clause B-1.1) Ratio of height to thickness (h/t)

    2.0 2.5 3.0 3.5 4.0 5.0

    Correction factors for brickworks*

    0.73 0.8 0.86 0.91 0.95 1.0

    Correction factors for blockworks*

    1.0 - 1.20 - 1.30 1.37

    *Interpolation is valid for interm ediate values.

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    12

    23

    Prism Testing Appendix B of IS:1905-1987

    Same material, joint thickness and workmanship as in field

    h > 400 mm Tested at 28 days

    4 mm plywood as and platens larger than prism Spherical seated in the machine Rate of loading 350-750 kN/min

    Masonry Prism strength

    24Madras Detailed Standard Specification 1956 (Reprint 1964)

    Effect of Mortar on Masonry Strength As proportion of lime in mortar increases

    Mortar loses strength But, masonry does not loose much strength

    Masonry Prism strength

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    13

    Elastic Modulus Elastic Modulus

    26

    Elastic Modulus Elastic Modulus in Compression

    tb

    tj

    P = y Anet

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    14

    27

    Elastic Modulus

    Elastic Modulus in Compression

    tb

    tj

    P = y Anet

    28

    Elastic Modulus

    Prism Testing Masonry Modulus Em < Brick Modulus Eb

    Block masonrytj=10mm, tb=200 mm, t=0.05

    Brick masonrytj=8mm, tb=57 mm, t=0.14

    0

    0.2

    0.4

    0.6

    0.8

    1

    1.2

    0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

    Clay brick

    Bric

    k

    Bloc

    k

    Block

    m

    b

    EE

    m

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    29

    Prism Testing

    But, if brick is softer than mortar, Em > EbIISc Bangalore data fb = 5.36 MPa, Eb = 730 MPa Ej = 6000 MPa (1 : 6) fj = 4.38 MPa Em = ~1100-1600 MPa

    Elastic Modulus

    30

    yCompressive Behaviour

    of Masonry

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    31

    Prism Testing Elastic Modulus Em

    Chord modulus for stress levels 0.05fm-0.33fm

    Stress

    Strain Strain

    Stress

    Em =

    fm

    0.33fm

    0.05fm

    Stress

    Strain

    Compressive Behaviour masonry Prisms

    32

    Compressive Stress-Strain Curves for Masonry Prisms5 bricks high prisms(400-410 mm high)

    10 mm thick mortar joints

    Typical vertical splitting failure

    Compressive Behaviour masonry Prisms

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    17

    33

    Prism Testing Clay Brick Units

    (4 manufacturers) Mortar (3 types-

    1:0:3, 1:0.5:4.5) Prism

    Compressive Behaviour

    0

    5

    10

    15

    20

    25

    30

    0.000 0.002 0.004 0.006 0.008 0.010 0.012

    Com

    pres

    sive

    Stre

    ss, M

    Pa

    MB

    O

    SAverage

    bb

    bb

    bb

    bb

    bb

    fEfEfEfEfE

    300317S260O312B300M

    (a)

    (b)

    (c)

    0369

    12151821

    0.000 0.005 0.010 0.015 0.020 0.025 0.030Co

    mpr

    essiv

    e St

    ress

    , MPa

    1:0.5:4.5 mortar

    1:0:6 mortar

    1:0:3 mortar

    jj

    jj

    jj

    jj

    fEfEfEfE

    2002154.5:0.5:11803:0:1175 6:0:1

    0

    2

    4

    6

    8

    10

    0.000 0.002 0.004 0.006 0.008 0.010

    Com

    pres

    sive

    Stre

    ss, M

    Pa

    1:0:6mortar1:0.5:4.5 mortar1:0:3 mortar

    '

    '

    '

    '

    5505704.5:0.5:15553:0:15506:0:1

    mm

    mm

    mm

    mm

    fEfEfEfE

    34

    Effect of Mortar & Unit on Masonry Strength Prominent increase

    when weaker mortar is used

    Higher strength mortar is not advisable

    A case for use of LIME in mortar

    Masonry Prism strength

    0

    2

    4

    6

    8

    10

    0 5 10 15 20 25 30Brick Strength, MPa

    Prism

    Stre

    ngth

    , MPa

    1:0.5:4.5 mortar

    1:0:6 mortar

    1:0:3 mortar

    B M S O

    0

    2

    4

    6

    8

    10

    0 5 10 15 20 25Mortar Strength, MPa

    Prism

    Stre

    ngth

    , MPa

    BM

    OS

    1:0:3

    1:0.5:4.5

    1:0:6 mortar

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    18

    35

    Effect of WA and IRA on Masonry Strength fb strongly dependent on IRA, rather than on WA

    Masonry Prism strength

    0

    5

    10

    15

    20

    25

    30

    M B O SBrick Type

    Bric

    k Pr

    oper

    ties

    Comp. strength, MPaWA, %IRA, kg/sq.m/min

    0

    10

    20

    30

    40

    0 1 2 3IRA, kg/m2/min

    Com

    p. st

    ress

    , MPa

    C r = - 0.77

    8 10 12 14 16WA, %

    C r = - 0.24

    36

    Non-linear Stress-Strain curves of bricks, mortar & masonry are determined

    Greater flexibility of lime mortar and masonry.

    0

    5

    10

    15

    20

    25

    Com

    pres

    sive

    Stre

    ss, M

    Pa Brick units

    1:0:6 Mortar cubesMasonry prism

    0

    5

    10

    15

    20

    25

    Com

    pres

    sive

    Stre

    ss, M

    Pa Brick units1:0:3 Mortar cubes

    Masonry prism

    0

    5

    10

    15

    20

    25

    0.000 0.005 0.010 0.015 0.020 0.025 0.030Strain

    Com

    pres

    sive

    Stre

    ss, M

    Pa Brick units

    1:0.5:4.5 Mortar cubes

    Masonry prism

    Compressive Behaviour

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    37

    Best performance shown by prisms constructed with Intermediate mortar (mortar containing lime)

    Masonry with Strongmortar

    Masonry with Intermediatemortar

    ~ 13% less

    ~ 50% more

    Failure Strain

    Prism Strength

    Importance of using lime in mortarSignificant improvement in Flexibility without considerable compromise with the Prism Strength

    Compressive Behaviour

    38

    Clay Brick UnitsEu = ~ 300 fu

    MortarEj = ~ 200 fj

    PrismEm = ~ 550 fm

    Elastic Modulus

    0

    2000

    4000

    6000

    8000

    10000

    12000

    0 10 20 30 40Brick compressive strength, MPa

    Bric

    k el

    astic

    mod

    ulus

    , MPa M bricks

    B bricks

    O bricks

    S bricks

    40 brick specimens

    C r =0.39

    bb fE 300

    bb fE 150

    bb fE 500

    0

    1000

    2000

    3000

    4000

    5000

    0 5 10 15 20 25Mortar compressive strength, MPa

    Mor

    tar e

    lasti

    c m

    odul

    us, M

    Pa 1:0:6 mortar1:0.5:4.5 mortar1:0:3 mortar

    27 mortar cube specimens

    C r =0.90

    jj fE 200jj fE 400

    jj fE 100

    0

    2000

    4000

    6000

    8000

    0 2 4 6 8 10 12Masonry prism strength, MPa

    Mas

    onry

    ela

    stic

    mod

    ulus

    , MPa 1:0:6 mortar

    1:0.5:4.5 mortar1:0:3 mortar

    84 masonry prism specimens

    C r =0.63

    '1100 mm fE

    '250 mm fE

    '550 mm fE

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    20

    39

    Control Points Defining Stress-Strain Curves of Masonry

    0.0

    0.2

    0.4

    0.6

    0.8

    1.0

    1.2

    0.000 0.002 0.004 0.006 0.008 0.010Strain

    Nor

    mal

    ized

    Stre

    ss

    1:0.5:4.5

    1:0:6

    1:0:3

    'mf

    '9.0 mf '75.0 mf

    '33.0 mf

    '6.0 mf '5.0 mf

    '2.0 mf

    6 Control Points corresponding to 6 significant events observed experimentally (4 in Rising and 2 in falling branch)

    Stress-Strain curves can be plotted for given Prism Strength

    Stress in terms ofPrism Strength

    Strain in prism for different mortar grades

    1:0:6 1:0:3 1:0.5:4.50.00 0.0000 0.0000 0.00000.33 0.0009 0.0005 0.00050.75 0.0021 0.0014 0.00150.90 0.0029 0.0021 0.00211.00 0.0036 0.0025 0.00300.60 0.0059 - -0.50 - 0.0045 0.00620.20 - 0.0053 0.0080

    Compressive Behaviour

    40

    6 Control Points:

    1. 0.33 : Stress-strain curves remain linear

    2. 0.75 : Vertical splitting cracks appear in bricks; masonry still resists loads without much deterioration

    3. 0.9 : Vertical splitting cracks propagate excessively

    4. : Ultimate stress level in masonry after which the load drops and strains increase excessively

    5. 0.5 : Proposed as maximum dependable compressive strength of masonry

    6. 0.2 : Residual compressive stress in masonry

    'mf'

    mf

    'mf'

    mf

    'mf

    'mf

    Compressive Behaviour

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    21

    41

    Analytical Model for Prism Strength of Masonry

    What is the need?- Significant variation in material properties geographically - Controlled compression testing of masonry prisms not always feasible

    A simple analytical model is required

    fb, fj : readily available in design codes or can be obtained easily by conducting tests

    - Can be conveniently used in the analytical model

    Compressive Behaviour

    42

    Analytical Estimation of Masonry Prism Strength

    Kaushiks Study:Unconstrained Linear Regression Analysis of

    using experimentally obtained compressive strengths

    Proposed Equation:'

    mf = 0.630.49

    bf0.32

    jf R2 = 0.93 (Coefficient of Determination)

    = 0.48 MPa (Standard Error of Estimate)

    Excellent Prediction

    'mf = K

    bf

    jf

    Compressive Behaviour

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    22

    43

    Proposed Analytical Model for Stress-Strain Curves of Brick Masonry

    Compressive Behaviour

    44

    Tri-Linear Stress-Strain Model

    Compressive Behaviour

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    23

    45

    Summary : Compressive Behaviour of Masonry

    Non-linear - e curves determined experimentally

    Relations suggested for estimation of Eb, Ej, and Em

    IRA more directly related (than WA) to fb

    Use of lime in mortar beneficial - increases ductility

    Analytical models developed for - e curves of masonry are fairly Accurate and Simpler and Tri-linear model is for use in computer analysis programs

    Compressive Behaviour

    46

    Concrete Block Masonry

    Material Testing for Compressive strength:Masonry blocks Mortar cubes Grout cylinders and prismsMasonry prisms (two blocks high)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    24

    47

    Prism Testing Grouted Prisms

    Note grouted cores which remained intact inside the prism

    [Brzev, BCIT]

    48

    Prism Testing Hollow Prisms

    Characteristic vertical splitting failure

    [Brzev, BCIT]

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    25

    49

    Test Results: Prisms (fm)

    Specimen Area (mm2) Load kN

    Compressive Strength (MPa)

    Avg. Compressive Strength (MPa)

    Standard Deviation

    (MPa)

    COV

    G1 54990 1322.15 24.0 22.9 1.4 6%G2 54990 263098 21.3

    G3 54990 288742 23.4 H1 30245 148178 21.8

    25.0 3.4 14%H2 30245 195669 28.8 H3 30245 183392 27.0 H4 30245 681.0 22.5 H5 - (5) 30245 480.0 15.9

    B1 30245 260648 38.3 37.8 1.3 4%B2 30245 246505 36.3

    B3 30245 263573 38.8 Notes: 1. G = Grouted Masonry Prism 2. H= Hollow Masonry Prism 3. B = Masonry block (both ends plain) 4. Average cross-sectional area of masonry blocks: Both ends plain: 30245 mm2 Regular stretcher: 32417 mm2 5. The strength of prism specimen H5 was not taken into account

    [Brzev, BCIT]

    Draft Code Approach for Elastic Modulus &

    Compressive Strength

    Draft Code Approach for Elastic Modulus &

    Compressive Strength

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    26

    51

    Masonry Prism strength

    fm and Em from prism testsBasic compressive strength, fb = 0.25 fmfm and Em from prism testsBasic compressive strength, fb = 0.25 fm

    Basic compressive strength, fb from unit compressive strength fu and mortar grade (Table 10, Draft IS: 1905)

    Basic compressive strength, fb from unit compressive strength fu and mortar grade (Table 10, Draft IS: 1905)

    CompressiveStrength & Modulus

    CompressiveStrength & Modulus

    Prism TestedPrism Tested

    No Prism TestedUNIT Strength Method:No Prism TestedUNIT Strength Method:

    Specified compressive strength, fm = 4fbEm = 550 fmSpecified compressive strength, fm = 4fbEm = 550 fm

    52

    IS:1905 Design Compressive StrengthsMasonry Prism strength

    UNIT Strength Method:UNIT Strength Method:

    Specified compressive strength fm = 4fb and Em = 550 fmSpecified compressive strength fm = 4fb and Em = 550 fm

    Sl.no

    Mortar Type

    Table 10: Basic compressive strength in MPa corresponding to masonry units of which height to width ratio does not exceed 0.75 and crushing strength in MPa is not less than

    3.5 5.0 7.5 10 12.5 15 17.5 20 25 30 35 40 1 H1 0.35 0.50 0.75 1.00 1.16 1.31 1.45 1.59 1.91 2.21 2.50 3.05 2 H2 0.35 0.50 0.74 0.96 1.09 1.19 1.30 1.41 1.62 1.85 2.10 2.50 3 M1 0.35 0.50 0.74 0.96 1.06 1.13 1.20 1.27 1.47 1.69 1.90 2.20 4 M2 0.35 0.44 0.59 0.81 0.94 1.03 1.10 1.17 1.34 1.51 1.65 1.90 5 M3 0.25 0.41 0.56 0.75 0.87 0.95 1.02 1.10 1.25 1.41 1.55 1.78 6 L1 0.25 0.36 0.53 0.67 0.76 0.83 0.90 0.97 1.11 1.26 1.40 1.06 7 L2 0.25 0.31 0.42 0.53 0.58 0.61 0.65 0.69 0.73 0.78 0.85 0.95

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    27

    Bond StrengthBond Strength

    54

    Bond Strength

    Most important property of hardened mortar Factors affecting bond strength

    Brick texture Greater for roughened surfaces Smaller for sanded finishes

    Brick suction IRA

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    55

    Factors affecting bond strength Flow

    Bond strength increases with increase in flow Time lapse between spreading of mortar and placing

    of brick affects mortar flow Should be minimised, especially on hot days

    Re-tempering (mixing water) Encouraged to compensate for water evaporating from mortar boardMay reduce compressive strength but increases bond strength Should be done within 2.5 hrs after mixing

    Flow measurement ASTM C109

    Bond Strength

    56

    Factors affecting bond strength Flow

    Flow measurement 2 cake of mortar dropped 0.5, 25 times in 15 s% flow = diameter of cake after testing/original diameter of 2

    Bond Strength

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    57

    Factors affecting bond strength Movement

    No tapping and attempt to move brick once mortar has begun to harden

    Proportion No precise combination, but type S mortar gives

    higher flexural strength (H2-6 MPa) Curing

    Wet curing generally produces higher bond strength

    Bond Strength

    58

    Bond strength Tests

    ASTM C 1072: Bond Wrench Test Flexural bond strength of each joint in brick prism Aliter E518, E72

    Bond Strength

    http://www.masonrysociety.org

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    30

    59

    Tension Bond Strength

    Various tests procedures and specimens have been suggested Bond wrench test, direct tension test, and crossed couplet test Each of these tests has its own drawbacks and problems

    Direct tension test Crossed couplet test

    60

    Tension Bond Strength

    A new z-shaped specimen proposed by Khalaf (2005) A simple test to evaluate the flexural bond strength by bending

    Plaster of Parispacking

    lb/2

    wb

    lb/2lb - tbar

    tb Brick Sample

    Plaster of

    Mortar Joint

    P

    Steel bar

    lb/2 lb/2

    LVDT

    Location of hinge forming at failure

    P

    lmj

    lb RA

    Brick weight, W Bar thickness, tbar

    ffb

    5/8 lmj

    Tensile bond stress distribution

    0.5 1.5

    1.5b b bar

    Ab bar

    l P l t WR

    l t

    2 2 2 2

    2

    0.5 0.5 0.75 1.25 0.5

    0.42 1.5b b bar bar b b bar

    fbmj b b bar

    l l t t P l l t Wf

    l w l t

    Tension Bond Strength, ffb

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    31

    61

    0.00

    0.05

    0.10

    0.15

    0.20

    0 0.2 0.4 0.6 0.8 1 1.2

    Tens

    ion

    bond

    stre

    ss (M

    Pa)

    Normalized displacement (mm/mm)

    Tension Bond Strength

    Failure was observed most commonly on the upper face of bed joint (or bottom face of upper brick) for clay and fly-ash masonry

    AAC block masonry with Polymer modified mortar failed along the centerline of the upper block

    Tension bond failure

    Typical failure for clay and fly-ash bricks AAC with Polymer mortar

    Flexural Tensile Strength

    Flexural Tensile Strength

    CE62

    5-Ma

    sonr

    y stru

    cture

    s/Dr D

    urge

    sh R

    ai/IIT

    K/20

    12

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    32

    63

    Flexural Strength

    Under the two-way action for mobilization of cracks in both the horizontal and the vertical direction, the flexural bond strength is crucial in normal as well as parallel directions to the bed joint.

    Tests conducted in accordance with BS EN 1052-2 (BSI 1999)

    l2

    l1 ls

    b wb

    l2

    l1 b

    wb

    ls

    1 22

    32f

    fb

    P l lf

    bw

    Flexural Strength, ff

    64

    flexural Tensile Strength

    Tension Normal to bed jointsEffective area

    hollow solidMPa050Fmortar2M GradeMPa070Fbetteror1M Grade

    t

    t

    .,.,

    0.21 MPa (Half-scaled brick Masonry)0.17 MPa (Full scale brick Masonry)

    l2

    l1 ls

    b wb

    IS 1905 Permissible values

    Experimental Ultimate Strength:

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    33

    65

    flexural Tensile Strength

    Tension Parallel to bed joints No direct tensile strength assumed normal to bed joint - just

    shear strength along bed jointsStrong units Weak units

    Effective

    MPa57funitsforMPa100F

    MPa10funitsforMPa140F

    utt

    utt

    ..

    .'

    '

    l2

    l1 b

    wb

    ls

    1.10 MPa (Half-scaled brick Masonry)1.02 MPa (Full scale brick Masonry)

    IS 1905 Permissible values

    Experimental Ultimate Strength:

    66

    Flexural Strength

    Flexural bond strength Plane of failure parallel to the bed joints = 0.17 MPa Plane of failure perpendicular to bed joints = 1.02 MPa

    Failure occurs between the inner (loading) bearings

    Failure under flexural loading

    0.0

    0.2

    0.4

    0.6

    0.8

    1.0

    0.0 0.5 1.0 1.5 2.0

    Flex

    ural

    stre

    ss (M

    Pa)

    Normalized displacement (mm/mm)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    34

    67

    Shear StrengthShear Strength

    68

    In-Plane Shear Behaviour of URM Walls

    Possible Modes of Shear Failure Failure through masonry units

    Strong mortar and weak units Sliding along bed joints

    Low vertical compressive stress Stair-steeping through bed and head joints

    Weak mortar and strong units

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    35

    69

    In-Plane Shear Strength For high axial pre-compression (> 2MPa)

    Mann & Muller (1982) Based on tensile cracking of units

    ftb = Tensile strength of brick= 0.33 fu= Axial pre-compression

    In-Plane Shear Behaviour of URM Walls

    tb

    ctb f

    f 145.0

    c

    70

    In-Plane Shear Strength For Low Pre-compression (< 2MPa)

    Mohr-Coulomb type relations

    In-Plane Shear Behaviour of URM Walls

    )&(.&.).&.

    ....

    HendrySinha 500MPa300Epperson( 220MPa370

    85070MPa451130

    stressaxialffactorfriction

    cohesionf

    c

    d

    c

    dc

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    36

    71

    Calculation of Shear Stress

    netavgv

    avgvnet

    v

    netv

    AVf

    f23

    AV

    23f

    bIVQf

    ,

    ,max,

    fv,max

    fv,avg.

    72

    Design criteria for shear UBC

    Clay units : Fv = 0.3fm < 80 psi [0.55 MPa] CMU : Fv = 34 psi [0.23 MPa] (M or S mortar)

    = 23 psi [0.16 MPa] (N mortar)Allowable stress increased by 0.2 fmd

    where fmd = Compressive stress due to dead loadsFv = Average shear stress = V/Anet

    In-Plane transverse Loading

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    37

    73

    Design criteria for shear ACI :

    Fv is lesser of1.5 fm psi [0.124 fm MPa] 120 psi [0.827 MPa]v + 0.45Pv / An

    where v =37 psi [0.26 MPa] for running bond, but not solid grouted= 37 psi [0.26 MPa] for stack bond & solid grout=60 psi [0.41 MPa] for running bond + solid grout

    15 psi [0.10 MPa] for masonry in other than running bond Shear Stress is Maximum Shear Stress

    Fv = VQ/(Anb)

    In-Plane transverse Loading

    74

    Design criteria for shear Permissible Shear Stress in Draft IS:1905

    In-plane permissible shear stress Fv lesser of0.1 + 0.2fd MPa0.5 MPa

    fd = compressive stress due to dead loads in MPa

    In-Plane transverse Loading

    m0.125 f

    00.10.20.30.40.50.6

    0 1 2 3

    0.1 + 0.2fd

    Allo

    wab

    le s

    tres

    s, M

    Pa

    Stress due to dead loads, MPa

    0.5 MPa or fm 16 MPa

    fm < 16 MPa0.125fm

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    38

    75

    Initial Shear Strength and Friction Factor

    One-brick and Two-brick triplets (for estimating the effect of vertical joint on the shear strength) Without pre-compression initial shear strength

    With pre-compression at 0.2, 0.4, 0.6 and 0.8 MPa friction factor

    76

    Initial Shear Strength and Friction Factor

    Test Setup Test was carried out in accordance with provisions of BS EN 1052-3: 2002 Two independent actuators used for lateral (shear) and vertical load Horizontal force applied on middle course of brick triplets Compressive force was applied gradually to required pre-

    compression level and maintained constant throughout the test

    One-brick triplet Two-brick triplet

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    39

    77

    Initial Shear Strength and Friction Factor

    Shear failure

    Initial Shear Strength Typical failure plane along the mortar

    bed; a failure line on either side of the middle brick

    For AAC masonry with Polymer mortar, the blocks failed in shear prior to shear failure of the bond

    0.0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

    Shea

    r stre

    ss (M

    Pa)

    Normalized displacement (mm/mm)

    Typical failure for clay and fly-ash bricks AAC with Fixoblock mortar

    78

    Initial Shear Strength and Friction Factor

    Friction Factor, Values agree well with the typical range for standard masonry

    = 0.70 to 1.20 which depends on the different combinations of brick units and mortars (Lourenco et al. 2004)

    0

    0.2

    0.4

    0.6

    0.8

    1

    0 0.2 0.4 0.6 0.8 1

    Fric

    tiona

    l stre

    ss (M

    Pa)

    Vertical pressure (MPa)

    = 0.88

    = 0.97

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    40

    79

    Diagonal tension (shear) strength

    Test method commonly used to estimate shear strength for both new and existing masonry constructions (ASTM E 519-07)

    0.707s

    n

    PSA

    In-situ testLaboratory test

    P = Applied load An = net area of the specimen

    80

    Diagonal tension (shear) strength

    Half-brick (Running bond) and full-brick thick (English bond) specimens were tested to examine the effect of the type of bond

    English bond specimen showed slightly higher strength compared to the running bond - attributed to presence of header bricks at alternate bed joints Typical failure is diagonal splitting of masonry wallets

    Diagonal tension failureRunning BondSs = 0.43 MPa

    English BondSs = 0.45 MPa

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    41

    81

    Comparison of Masonry typesComparison of Masonry types

    DEPARTMENT OF CIVIL ENGINEERING, IIT KANPUR

    PropertiesConventional Bricks Blocks

    Clay Fly-Ash A Fly-Ash B AAC1:1:6 1:4 1:1:6 1:4 1:1:6 1:4 1:3 PM1

    Compressive Strength2 3.89 3.81 3.03 3.57 7.33 6.82 2.05 2.38Elastic Modulus 1646 1344 2382 2605 5623 6256 1505 2107Split Tensile3 - - - - - - 0.13 0.34Tension Bond Strength 0.11 0.09 0.19 0.17 0.14 0.10 0.03 0.12Bed-Joint Shear Strength 0.17 0.19 0.23 0.18 0.29 0.27 0.10 0.32Diagonal Tension Strength

    - - - - - - 0.11 0.30

    1 Polymer modified mortar with water retention properties2 Compressive strength of AAC masonry obtained on 5-brick stack bond prism in half-scale3 Splitting tensile strength of thin bed mortar joint

    ConventionalBricksandAACmasonryproperties

    Research at IIT Kanpur

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    1

    Short Course on Seismic Design of Reinforced and Confined Masonry Buildings

    February 17-21, 2014, IIT Gandhinagar, India

    Acknowledgement

    Text Book: Geotechnical Earthquake Engineering, by S.L. KramerText Book: Dynamics of Structure, by Anil

    K ChopraLecture Notes by Prof A M Reinhorn,

    SUNY, BuffaloShort-course materials previously

    prepared by Profs. D C Rai, S K Jain and CVR Murthy

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    2

    EarthquakebyDefinition

    Anearthquakeisasudden,rapidshakingoftheEarthcausedbythereleaseofstrainenergystoredinrocks.

    LayersoftheearthLayered(likehardboiledegg)

    Crustisliketheshell~2540km beneaththecontinents~6070km beneathsomeyoungmountainranges~asthinas5km beneaththeoceanfloors

    Mantleislikethewhite~Plastic,semisolidconsistency~Depthofthemantleisabout2,850km

    CoreisliketheyolkLiquidoutercore:~2260km indepthSolidmetalliccore:~Fe&Ni~ContinuestotheEarthscenter

    Crust

    Mantle

    Outer Core

    Inner Core

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    3

    Earthquakes: Why and Where?

    Continental Drift Theory

    Wegener (1915)Earth had only one large continent, called

    Pangaea, in 200 million years agoPangaea broke into pieces and drifted leading

    into the present configuration of the continents

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Drift of Pangaea

    Theory Plate Tectonics

    HypothesisEarth surface consists of a number of large

    intact blocks, called platesThese plates move with respect to each other

    Earth crust is divided into six continental sized platesAfrican, American, Antarctic, Australia-Indian,

    Eurasian and Pacific

    into Fourteen sub-continental sized plate

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Major Plates: Arrow indicating the direction of plate movements

    Plate Boundaries

    At the boundaries, larger plates are broken into smaller platelets or micro-plates

    Due to continuous plate movement, relative deformation between plates occur at the plate boundaries

    Strain energy build up and releaseCause of earthquakes

    Map of earthquake epicenters are near the plate boundaries

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Map of Earthquake Epicenters

    Driving Force for Plate Movements

    Thermo-mechanical equilibrium of earths materials Upper part of mantle is

    in contact with relatively cool crust

    Lower part of mantle is inc contact with relatively hot outer core

    Temperature gradient and variation of mantle density with temperature

    Cooler materials begins to sink and denser materials begins to rise---leading to convection current

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    7

    Types of Plate Boundaries

    Spreading Ridge BoundariesPlates move apart

    from each other in certain areas

    Molten rock from underlying mantle rises to the surface

    After cooling, it becomes part of the spreading plates

    Plates grow at the spreading ridges

    Types of Plate Boundaries

    Subduction Zone BoundariesSize of earth crust remains

    constantGrowth of plate at the

    spreading ridges MUST be compensated by consumption of materials at other locationsResults in subduction zoneTwo plates move toward each

    otherOne plate plunges or subducts

    beneath the other

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Transform Fault Boundaries

    Transform fault boundariesWhen plates

    cross each other without creating a new crust or consuming the old crust

    Interrelating Plate Boundaries

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Plate BoundariesViewed in Smaller Scale

    Plate tectonic theory describes the movement of plates through three types of plate boundaries

    Actual movement is quiet complicated when viewed in smaller scaleBreaking of the plates into a large number of

    microplates and trapped into larger plates Movement between two portions of crust will take

    place on a new or pre-existing weaker plane (or offset) in geologic structure---FAULTS

    Length: several meters to hundreds of kilometers Depth: several tens of kilometers from the ground

    surface

    Defining a Fault Geometry

    Strike: horizontal line produced by the intersection of fault plane and a horizontal plane

    Dip: downward slope of the fault plane Azimuth: Orientation of the strike wrt to North

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Characterization of Faults

    Usually based on Fault movementDirection of dipDirection of strikeMay be along both but one of these as

    predominant

    Dip-Slip Movement

    Normal FaultHorizontal component of

    the movement is extensionalAssociated with the tensile

    stress and horizontal lengthening of the crust Materials above the

    inclined fault (hanging wall) moves downward relative to the materials below the fault (foot wall)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Dip-Slip Movement Reverse Fault Horizontal component of the

    movement is Compressional Associated with the

    compressive stress and horizontal lengthening of the crust

    Materials above the inclined fault (hanging wall) moves upward relative to the materials below the fault (foot wall)

    Thrust Fault A special case of Reverse Fault

    when dip angle is small

    Strike-Slip movement

    Fault movement is parallel to the strikeRight lateral strike-slip

    faultObserver standing on one

    part of the fault would observe the ground on other side of the fault moving towards right

    Left lateral strike-slip fault

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    12

    How Earthquakes Occur?

    Brittle Rupture BrittleMaterial (Forexample,Rock) F

    F

    Elongation of Bar

    Forc

    e F

    RuptureRupture

    0

    Final elongation is small

    Maximum Force

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    13

    Elastic Rebound Theory

    Analogy of Elastic Rebound

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Elastic Stress and Slip

    Time (years)

    StrengthEnergy Build-Up

    Elas

    tic S

    tres

    s

    Energy Release

    Cum

    ulat

    ive

    Slip

    C

    A

    Slip

    A B

    C

    A

    B

    C

    EQ

    EQ

    Time (years)

    EQ

    Reservoir Triggered Earthquake

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Basic Terminology in Earthquake Engineering And Engineering

    Seismology

    Focus (Hypocenter) Pointwheremotionfirststarts

    Area/volume ruptured

    Focus

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Epicenter Projectionoffocusonground

    90

    Focal Depth Depthoffocusbelowground

    300km DeepFocusEQs

    Epicenter

    Focus

    90

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Epicentral Distance DistanceofepicenterfrompointofinterestontheEarth

    EpicentralDistance

    Station

    Station

    1o = 112 km

    Epicenter

    Focus

    o

    Epicenter

    Hypocentral Distance DirectdistancefromFocustoStationofinterest

    Epicenter

    Focus

    Epicentral Distance

    Fault Rupture

    Focal Depth

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Foreshocks/Aftershokes Eventsofshakingbefore/afterthemainEQevent

    Size

    Time

    Main Shock

    Foreshocks Aftershocks

    Seismic Waves

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Source to Site Travel Path

    EQ

    Surface Waves

    Fault Rupture

    Body Waves

    Structure

    Soil

    Geologic Strata

    Body WavesPrimary or P-wave

    Horizontal tension and compression waves, which travel in the direction of wavefront

    High frequency First wave to reach a structure

    Direction of Energy Transmission

    P-WavesPush and pull

    CompressionExtension

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Body WavesSecondary or S-waveShear waves, which travel perpendicularly to the

    wavefrontLower frequencyGreater amplitudeMost destructive vibrations

    Direction of Energy Transmission

    Side to side

    Up and downS-Waves

    Body Wave Propagation

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Surface WavesLove WaveHorizontal waves traveling on the ground

    Love WavesSideways in horizontal plane

    Direction of Energy Transmission

    Surface WavesRayleigh WaveVertical wave traveling on the ground surfaceRetrograding ellipse

    Rayleigh WavesElliptic in vertical plane

    Direction of Energy Transmission

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Surface Wave Propagation

    Types of Ground Motion and Characteristics

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

    23

    Teleseismic Events LowAmplitudeVibrations

    Longdistanceevents Lowfrequency Usuallydisplacements EarthScientists

    0200 400 600 800 1000 1200

    Am

    plitu

    de

    Time (s)

    Teleseismic Earthquake Recording

    P PP SSurface Waves

    Strong Motion Events StrongGroundMotions

    Nearfieldgroundmotions RelativelyHighfrequencycontents Usuallyaccelerations StructuralEngineers

    -0.3-0.2-0.1

    00.10.2

    0.3

    0 10 20 30 40 50 60 70 80

    Acc

    n. (g

    )

    PGA=0.32g

    Time (seconds)

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Ground Motion Characteristics PeakGroundParameters

    Acceleration(PGA) Velocity(PGV) Displacement(PGD)

    PGA and PGV of Some Recorded Events

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Other Parameters affecting Structural Performance

    Parameters DurationofSignificantShaking FrequencyContent

    Factors Affecting Recorded Motion

    Influenceof MagnitudeofEQ Sourcemechanism

    Typeoffaulting Distancefromsource

    Soil/rockmediumalongtravelpath

    Localsoilsite,geology,topology,etc.,.

    Attenuation with Distance

    Fault

    Fault

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Seismic Instruments

    Early Seismograph

    MagnetString

    Pendulumbob

    RotatingdrumPen

    Support

    Chartpaper

    Directionofshaking

    AnchoredtotheGround

    HorizontalShaking

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Early SeismographVerticalShaking

    Inertial Seismometers

    Mass on rod type Mass on spring Natural frequency of

    system is far higher than the predominant frequency contents of ground motion

    Separate units to measure horizontal and vertical shaking

    Weight of the bob acts differently to horizontal and vertical units

    Special design requirement to record vertical shaking

    Mass m

    Spring k

    Damping cSensorSensor

    2

    2

    2 n n n g

    n g

    u t u t u t u t

    u t u t

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Galperin Configuration Each sensor is mounted at an angle of 54.74o wrt

    vertical with 120o spacing when projected onto horizontal plane

    No special design for any of the three

    TriaxialgeometryoftheStreckeisen STS2seismometer

    Instruments and Functions Measureonlytranslations Nomenclature

    Seismometre Sensor

    Seismograph Sensor+RecordingDevice+TimeDevice

    RecordsDisplacementversus Time Seismoscope

    Instrument RecordsPeakDisplacement

    Seismogram GraphorRecord

    ObtainedfromaSeismograph

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Instruments and Classifications Classification

    Seismographs LowAmplitudeVibrations(longdistanceevents) Displacement

    RangerSS1 StrongMotionInstruments

    HighAmplitudeVibrations(nearfieldstrongevents) Acceleration

    Examples Digital

    DigitalStrongMotionAccelerograph(DSA1,3) SolidStateAccelerograph(SSA1,2)

    Analog StrongMotionAccelerograph(SMA1,SMA2,SMA3)

    Seismic Strong Motion Array

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Some Indian ArrayClosely spaced strong motion instruments

    Shillong Array

    !!!!

    Kangra ArrayUttar Pradesh Array

    Array in Taiwan

    DenseSeismicarrayatLotung

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Locating the Epicenter

    Arrival of P and S waves Differentarrivaltimes

    P S

    P-waves : 1.5-8 km/secS-waves : 60-70% of P-waves (1-5 km/sec)

    Speeds may vary Ratio between average speeds of P and S waves

    is quite constant! Time-delay between arrival of P-and S-waves

    is used to estimate location of epicenter

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Differential Arrival TimeTi

    me

    elap

    sed

    afte

    r sta

    rt o

    f EQ

    (s

    ec)

    Distance from Earthquake (km)

    Arrival of S-WaveArrival of S-Wave

    Arrival of P-WaveArrival of P-Wave

    A CB

    Epicentral Distance Estimates

    ArrivaltimesofPandSwaves Wavevelocitiesintheregion

    PS V1

    V1

    PS

    SP

    td

    Vd

    Vdt

    VV

    Focal Distance d

    StationEpicenter

    Focus

    Approximate Distance (km) = t 8 km/s!Approximate Distance (km) = t 8 km/s!

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Triangulation to Estimate Epicenter

    Station 3

    Station 1

    Station 2

    Strength and Impact of Earthquake

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Magnitude versus Intensity

    Bright(100 lumens)

    Normal(50 lumens)

    Dull(20 lumens)

    Near

    Far

    100 Watt Bulb Magnitude

    Intensity

    Magnitude versus Intensity

    Wattage isakintoEQMagnitude

    Brightness isakintoEQIntensity

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Earthquake Magnitude

    QuantitativemeasureofphysicalshakinggeneratedbytheEQ

    SizeoftheEarthquake

    Waysofmeasuring Motion Energy

    Richter Magnitude---Background

    WoodAndersonTorsionSeismograph

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Richter Magnitude

    Richter Magnitude

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Richter Magnitude

    Richter Magnitude

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Richter Magnitude

    Richter Magnitude

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Richter Magnitude

    Richter Magnitude

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Richter Magnitude

    Nomogram

    Richter Magnitude

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Richter Magnitude

    Evolution of Magnitude Scales

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Evolution of

    Energyreleasedis30timesifMagnitudeisincreasedby1order

    Sub-Topic

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Evolution of

    Evaluation of

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Evolution of

    Evolution of SaturationofMagnitudeScales

    Mag

    nitu

    de

    Moment Magnitude Mw

    MwMw

    MSMS

    MLML

    MbMb

    4 6 8 10

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Evolution of

    Impact of Earthquake

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Earthquake Intensity QualitativemeasureofstrengthofshakingmanifestedatagivenplaceduringtheEQ

    InfluenceoftheEarthquake

    Beforeseismographs,ItalianseismologistG.Mercalli andotherEuropeanscientistsclassifiedearthquakesbythedamagetheyproducedqualitatively

    IntensityScaleisaRomannumeralIXIIpointscaletorate

    Buildingdamage Groundmovements Humanimpactduetoanearthquake

    Many Intensity Scales 1883:RossiForelScale IX

    DeRossiandForel 1902:MercalliScale IXII

    Mercalli 1931:ModifiedMercalliScale IXII

    WoodandNeumann 1956:ModifiedMercalliScale IXII

    (1956Version) Richter

    1964:MSKScale IXII Medvedev,Sponheuer,Karnik

    1897 Great

    Assam EQ

    1897 Great

    Assam EQ

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Intensity Scales NewerScales

    Notwidelyusedyet 1998EuropeanMacroseismicScale IXII

    Firstproposedin1981;modifiedin1992,1998

    JapanMeteorologicalAgencyScale 17 UsedinJapanandTaiwan

    Arabic Numerals!!!

    Arabic Numerals!!!

    Shortened Mercalli Scale I Onlyinstrumentdetectit II Peoplelyingdownfeelit III Peopleonupperfloorsofbuildingfeelit,

    butmaynotknowthatitisearthquake IV Peopleindoorswillprobablyfeelit,

    butthoseoutsidemaynot. V Nearlyeveryonefeelsit

    andwakesupevenifsleeping. VI Everyonefeelsthequake

    anditshardtowalk. VII Itishardtostand.

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    Shortened Mercalli Scale VIII Peoplewillnotbeabletodrivecars.

    Poorlybuiltbuildingsmayfall.Chimneysmayfall.

    IX Mostfoundationsaredamaged.Thegroundcracks.

    X Mostbuildingsaredestroyed.Wateristhrownoutofriversandlakes.

    XI Railsarebent.Bridgesandundergroundpipelinesareputoutofservice.

    XII Mostthingsareleveled.Largeobjectsmaybethrownintotheair.

    MSK Intensity Scale (1964 Version) RussianScientists

    Medvedev,Sponheuer andKarnik

    TypesofStructures(Buildings) StructureABuildingsinfieldstone,ruralstructures,adobehouses,clayhouses

    StructureBOrdinarybrickbuildings,buildingsoflargeblockandprefabricatedtype,halftimberedstructures,buildingsinnaturalhewnstone

    StructureCReinforcedconcretebuildings,wellbuiltwoodenstructures

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    MSK (1964 Version) Definitionofquantity

    Single,few :~5% Many :~50% Most :~75%

    MSK (1964 Version) Classification of damage to buildings

    Grade 1 : Sight damage Fine cracks in plaster, fall of small pieces of plaster

    Grade 2 : Moderate damage Small cracks in walls, fall of fairly large piece of plaster,pantiles slip off, cracks in chimneys, parts of chimneys falldown

    Grade 3 : Heavy damage Large cracks in walls, fall of chimneys

    Grade 4 : Destruction Gaps in walls, parts of buildings may collapse, separateparts of the building lose their cohesion, inner wallscollapse

    Grade 5 : Total damage Total collapse of buildings

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    MSK (1964 Version) ArrangementoftheScale

    Introductorylettersareusedinparagraphsthroughoutthescaleasfollows:(a) Persons and surroundings(b) Structures of all kinds(c)Nature

    MSK (1964 Version)MSKIntensityScale

    I.Notnoticeable(a)Theintensityofvibrationsisbelowthelimitofsensibility;thetremorisdetectedandrecordsbyseismographsonly.

    II.Scarcelynoticeable(veryslight)(a)Vibrationisfeltonlybyindividualpeopleatrestinhouses,especiallyonupperfloorsofbuildings.

    III.Weak,partiallyobservedonly(a) Theearthquakeisfeltindoorsbyafewpeople,outdoorsonlyinfavourable circumstances.Thevibrationislikethatduetothepassingofalighttruck.Attentiveobserversnoticeaslightswingingofhangingobjects.

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    MSK (1964 Version)IV.Largelyobserved

    (a) Theearthquakeisfeltindoorsbyafewpeopleoutdoorsbyfewpeople.Hereandtherepeopleawake,butnooneisfrightened.Thevibrationislikethatduetothepassingofaheavilyloadedtruck.Windows,doors,anddishesrattle.Floorsandwallscreak.Furniturebeginstoshake.Hangingobjectsswingslightly.Liquidsinopenvesselsareslightlydisturbed.Instandingmotorcarstheshockisnoticeable.

    (b)(c)

    MSK (1964 Version)V.Awakening

    (a)Theearthquakeisfeltindoorsbyall,outdoorsbymany.Manysleepingpeopleawake.Afewrunoutdoors.Animalsbecomeuneasy.Buildingstremblethroughout.Hangingobjectsswing.Picturesknockagainstwallsorswingoutofplace.Occasionallypendulumclocksstop.Unstableobjectsmaybeoverturnedorshifted.Doorsandwindowsarethrustopenandslambackagain.Liquidsspillinsmallamountsfromwellfilledopencontainers.Thesensationofvibrationislikethatduetoaheavyobjectfallinginsidethebuilding.

    (b)(c)Slightwavesonstandingwater;sometimeschangeinflowof

    springs.

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    MSK (1964 Version)VI.Frightening

    (a) Feltbymostindoorsandoutdoors.Manypeopleinbuildingsarefrightenedandrunoutdoors.Afewpersonslosetheirbalance.Domesticanimalsrunoutoftheirstalls.Inmanyinstances,dishesandglasswaremaybreak,booksfalldown,picturesmove,andunstableobjectsoverturn.Heavyfurnituremaypossiblymoveandsmallsteeplebellsmayring.

    (b) DamageofGrade1issustainedinsinglebuildingsofTypeBandinmanyofTypeA.DamageinsomebuildingsofTypeAisofGrade2.

    (c) Cracksuptowidthsof1cmpossibleinwetground;inmountainsoccasionallandslips;changeinflowofspringsandinlevelofwellwater.

    MSK (1964 Version)VII.Damagetobuildings

    (a) Mostpeoplearefrightenedandrunoutdoors.Manyfinditdifficulttostand.Thevibrationisnoticedbypersonsdrivingmotorcars.Largebellsring.

    (b)InmanybuildingsofTypeC,damageofGrade1iscaused;inbuildingsofTypeB,damageisofGrade2.MostbuildingsofTypeAsuffersdamageofGrade3,someofGrade4.Insingleinstances,landslipsofroadwayonsteepslopes;cracksinroads;seamsofpipelinesdamages;cracksinstonewalls.

    (c)Wavesareformedonwater,andismadeturbidbymudstirredup.Waterlevelsinwellschange,andtheflowofspringschanges.Sometimesdryspringshavetheirflowrestoredandexistingspringsstopflowing.Inisolatedinstances,partsofsandyorgravellybanksslipoff.

  • Short Course on Sesimic Design of Reinforced and Confined Masonry Buildings, IIT Gandhinagar, Feb 17-21, 2014

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    MSK (1964 Version)VIII.Destructionofbuildings

    (a) Frightandpanic;alsopersonsdrivingmotorcarsaredisturbed.Hereandtherebranchesoftreesbreakoff.Evenheavyfurnituremovesandpartlyoverturns.Hanginglampsaredamagedinpart.

    (b) MostbuildingsofTypeCsufferdamageofGrade2,andfewofGrade3.MostbuildingsofTypeBsufferdamageofGrade3.MostbuildingsofTypeAsufferdamageofGrade4.ManybuildingsofTypeCsufferdamageofGrade4.Occasionalbreakingofpipeseams.Memorialandmonumentsmoveandtwist.Tombstonesoverturn.Stonewallscollapse.

    (c)Smalllandslipsinhollowsandonbankedroadsonsteepslopes;cracksingroundupto widthsofseveralcentimeters.Waterinlakesbecometurbid.Newreservoirscomeintoexistence.Drywellsrefillandexistingwellsbecomedry.Inmanycases,changeinflowandlevelofwaterisobserved.

    MSK (1964 Version)IX.Generaldamagetobuildings

    (a)Generalpanic;considerabledamagetofurniture.Animalsruntoandfroinconfusion,andcry.

    (b)ManybuildingsofTypeCsufferdamageofGrade3,andafewofGrade4.ManybuildingsofTypeBshowadamageofGrade2andafewofGrade5.ManybuildingsofTypeAsufferdamageofGrade5.Monumentsandcolumnsfall.Considerabledamagetoreservoirs;undergroundpipespartlybroken.Inindividualcases,railwaylinesarebentandroadwaydamaged.

    (c)Onflatandoverflowofwater,sandandmudisoftenobserved.Groundcrackstowidthsofupto10cm,onslopesandriverbanksmorethan10cm.Furthermore,alargenumberofslightcracksinground;fallsofrock,manylandslidesandearthflows;largewavesinwater.Drywellsrenewtheirflowandexistingwellsdryup.

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    MSK (1964 Version)X.Generaldestructionofbuildings

    (a)(b)ManybuildingsofTypeCsufferdamageofGrade4,andafewofGrade5.ManybuildingsofTypeBshowdamageofGrade5.MostofTypeAhavedestructionofgrade5.Criticaldamagetodykesanddams.Severedamagetobridges.Railwaylinesarebentslightly.Undergroundpipesarebentorbroken.Roadpavingandasphaltshowwaves.

    (c) Inground,cracksuptowidthsofseveralcentimeters,sometimesupto1meter.Paralleltowatercoursesoccurbroadfissures.Loosegroundslidesfromsteepslopes.Fromriverbanksandsteepcoasts,considerablelandslidesarepossible.Incoastalareas,displacementofsandandmud;changeofwaterlevelinwells;waterfromcanals,lakes,rivers,etc.,thrownonland.Newlakesoccur.

    MSK (1964 Version)XI.Destruction

    (a)(b)Severedamageeventowellbuiltbuildings,bridges,waterdamsandrailwaylines.Highwaysbecomeuseless.Undergroundpipesdestroyed.

    (c) Groundconsiderablydistortedbybroadcracksandfissures,aswellasmovementinhorizontalandverticaldirections.Numerouslandslipsandfallsofrocks.Theintensityoftheearthquakerequirestobeinvestigatedspecifically.

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    MSK (1964 Version)XII.Landscapechanges

    (a)(b)Practicallyallstructuresaboveandbelowgroundaregreatlydamagedordestroyed.

    (c)Thesurfaceofthegroundisradicallychanged.Considerablegroundcrackswithextensiveverticalhorizontalmovementsareobserved.Fallsofrockandslumpingofriverbanksoverwideareas,lakesaredammed;waterfallsappear,andriversaredeflected.Theintensityoftheearthquakerequirestobeinvestigatedspecially.

    M-I-PGA Relationship

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    Magnitude-PGA PeakGroundAccelerations(PGA)

    MMI V VI VII VIII IX XPGA (g) 0.03-0.04 0.06-0.07 0.10-0.15 0.25-0.30 0.50-0.55 >0.60

    -0.3-0.2-0.1

    00.10.2

    0.3

    0 10 20 30 40 50 60 70 80

    Acc

    n. (g

    )

    PGA=0.32g

    Time (seconds)

    Magnitude-Intensity

    Magnitudeversus I GutenbergandRichter,1956

    ML (2/3)I0+1 Forusingthisequation,theRomannumbersofintensityarereplacedwiththecorrespondingArabicnumerals,e.g.,intensityIXwith9.0

    Severalotherrelations

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    Attenuation Relation

    Strong Motion Attenuation Reductionwithdistance

    1979 Imperial Valley 1979 Imperial Valley M~6.6 Earthquakes M~6.6 Earthquakes

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    New Generation Strong Motion Attenuation

    Many relations

    Isoseismals 2001BhujEarthquake

    IX

    VIII

    X

    VII

    Meizoseismal regionMeizoseismal region

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    Intensity Attenuation

    Comparison of attenuation relation (M=6 ) in India (ours), Philippinse(Benjamin, 1983), Turkey (Yarar et al., 1984) and Jamaica (Wang et al., 1995)

    Indian Earthquake Scenario

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    Geographical Layout & Tectonic Plate Boundaries

    Deccan Shield

    Gangetic Plains

    Himalayas

    Bay of Bengal

    Arabian Sea

    Indo-Australian Plate

    Eurasian Plate

    Narmada Plains

    GodavariPlains

    MahanadiPlains

    Some Past Earthquakes

    2001 Bhuj 1934 Bihar-Nepal

    1905 Kangra

    1950 Assam1897 Assam

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    Indian Seismic Zone Map

    Zone Factor

    IS 1893-part-1

    PGA at MCE = ZPGA at DBE = Z/2On What BASIS??Need of Seismic Hazard Analysys

    Seismic Zone II III IV VZ 0.10 0.16 0.24 0.36

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    Deterministic Seismic Hazard Analysis

    Probabilistic Seismic Hazard Analysis

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    Typical Results from PSHA

    Questions?

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