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1. EARTHQUAKE RESISTANT BUILDINGS (MASONRY)

2. EarthquakeResistantStructures • Designedto withstandearthquake • Can’tbe entirelyimmune todamage • Preventscollapsing • Limitedlossoffunctionality • Masonry • Mostimportant constructionmethod • Canresist loadsandenvironmentalimpact • Fireresistant, Durable,Thermalcapacity Introduction

3. Shouldn’tbebrittleorcollapsesuddenly • ResistingElements • Tiedtogether • Goodfoundation • Goodqualitymaterial • Suitablyreinforced GeneralPrinciples

4. Seismicwaves • When pieces of crustal rock suddenly slip and move, they release enormous amountsofenergy,whichthenpropagatesthroughthe crustasseismic waves. • Pwaves • Swaves CauseofEarthquake

5. Underminorbutfrequentshaking,themainmembersof the buildingsthatcarryverticaland horizontalforces shouldnotbe damaged;howeverbuildingspartsthatdo notcarryloadmaysustainrepairabledamage. • Undermoderate butoccasionalshaking,themain membersmaysustainrepairabledamage, whilethe other partsthatdonotcarryloadmaysustainrepairable damage. • Understrongbutrare shaking,the mainmembers may sustainseveredamage,butthe buildingshouldnot collapse. DesignPhilosophy

6. BaseIsolation MethodsofEarthquakeResistantDesign EnergyDissipationDevices

7. Masonryhasbeenpopularthroughthe agesforitsfire resistance,itsthermalcapacityandits durability. Useofstrongmortars,highstrengthmasonry,added reinforcement,improveddetailingandthe introductionofgoodanchoragebetweenmasonry wallsandfloorsandroofshaveenhancedthe resistanceofmasonrytoseismicstress. DesigningMasonryBuildings

8. MasonryMaterials Masonry Units Mortar ConcreteInfill ReinforcingSteel Figure:Typicalbedjointreinforcement

9. Unreinforced Masonry ReinforcedMasonry 1.Reinforced hollowunits masonry. ConstructionSystems 2.Reinforcedcavitymasonry.

10. This is a construction system where masonry structural walls are surroundedon allfoursideswithreinforcedconcrete. ConfinedMasonry Figure:Methodsof confiningmasonry

11. Wallsaretobeuniformlydistributedalongeachprincipalaxisof theplan. • Theminimumthicknessofstructuralwallsshouldbe240mm.The • totalcross-sectionalareaofstructuralwallsalongeachofthetwo axes shouldnotbe less than3% of thegrossfloorarea. • Adequate foundations and good anchorage between walls and floorsareessential. • Distances between structuralwalls of reinforced masonry should • notbemorethan6m;distancesinconfinedmasonryshouldnot • bemorethan8m. • Partitions shouldbereinforcedwith6 mmøbarsplacedatthebed • joints withverticalspacingof600 mmin ordertopreventtheir out-of-planeinstability. Walls GeneralPrinciples

12. Lintels should have a minimum of 250 mm bearing length at both ends to prevent local collapse due to crushing of supports during an earthquake. The widthofa lintelshouldnot belessthan150mm. In thecaseof openingslarger in area than 2.5 m2, the lintel shouldbeanchoredto thetie columnsasshowninFigure (a) Ifthedistance betweentopoflintel andundersideof beamaboveisless than 60 cm, the two should be united asshowninFigure(b). Lintels

13. During earthquakes, floors and roofs should act as rigid horizontal diaphragms, which distribute the seismic forces among structural walls inproportiontotheirstiffness. TieBeams Thefunctionoftiebeamsistotransferhorizontalshearinducedby the earthquakes from the floor and roof to the structural walls. They connect the structural walls with each other and improve the rigidity of thehorizontaldiaphragms. FloorsandRoofs

14. Cantilever Slabsand Overhangs These elements can cause harmful vertical vibration during heavy earthquakes.Toreducethis,spansshouldnotexceedthoseshownon Figure below.

15. Masonrybuildingshaveperformedwell inseveralearthquakesworldwide. This constructionpracticeis widelyusedinmanycountriesand regions for the followingreasons: • It is basedontraditionalconstructionpractice; • Itdoesnot requirehighlyqualified labour(asis thecasewith RC frame construction); • Ithas abroadrangeofapplications- it can beusedforsingle-family houses as wellasfor medium-riseapartmentbuildings. • Goodearthquakeperformance isbasedonthefollowingpremises: • Useofgoodqualitymaterials, • Goodquality concrete and masonryconstruction,and • Simplearchitecturaldesign. Concluding Remarks