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1、6.3Theshearbehaviorofbeamwithreinforcement◆Aftercrack,theshearmechanismofthebeamwithstirrupchangedfromtensilechordarchtotrussarch.◆Theconcretebetweendiagonalcrackislikecompressiondiagonal.◆Thestirrupactionislikeverticaltensilechord.◆Thecricalcrackonthetopandcompressiveconcreteislike
2、compressionchord.◆Tensionreinforcementisliketensionchord.Tensionreinforcementisliketensionchord6.3有腹筋梁的受剪性能6.3Theshearbehaviorofbeamwithreinforcement◆Tensionreinforcementisliketensionchord.Tensionreinforcementisliketensionchord◆Thestirrupstransformloadfromconcretetothecompressioncho
3、rdandincreasecompressiveactionofconcrete,aggregateinterlock,andtransformpartofloadstothesupport(archmechanism)6.3有腹筋梁的受剪性能6.3有腹筋梁的受剪性能◆梁中配置箍筋(stirrup),出現(xiàn)斜裂縫后,梁的剪力傳遞機(jī)構(gòu)由原來無腹筋梁的拉桿拱傳遞機(jī)構(gòu)轉(zhuǎn)變?yōu)殍旒芘c拱的復(fù)合傳遞機(jī)構(gòu)◆斜裂縫間齒狀體混凝土有如斜壓腹桿(compressiondiagonals)◆箍筋的作用有如豎向拉桿◆臨界斜裂縫上部及受壓區(qū)混凝土相當(dāng)于受壓弦桿(compressioncho
4、rd)6.3有腹筋梁的受剪性能6.3有腹筋梁的受剪性能◆縱筋相當(dāng)于下弦拉桿(tensionchord)◆箍筋將齒狀體混凝土傳來的荷載懸吊到受壓弦桿,增加了混凝土傳遞受壓的作用,斜裂縫間的骨料咬合作用,還將一部分荷載傳遞到支座(拱作用archmechanism)6.3有腹筋梁的受剪性能一、Stirrupaction箍筋的作用◆Aftercrack,stirrupsbeartensionstressandincreasesheartransformationcapacityofbeam;斜裂縫出現(xiàn)后,拉應(yīng)力由箍筋承擔(dān),增強(qiáng)了梁的剪力傳遞能力;◆Thestirrup
5、scontrolledtheextensionofcrackandincreasedshear-compressionzero,V,V;箍筋控制了斜裂ca縫的開展,增加了剪壓區(qū)的面積,使Vc增加,骨料咬合力Va也增加;◆Thestirrupssuspendedreinforcement,delayedsplittingcrack,enhanceddowelactionVdofreinforcement;吊住縱筋,延緩了撕裂裂縫的開展,增強(qiáng)了縱筋銷栓作用Vd;6.3有腹筋梁的受剪性能一、Stirrupaction箍筋的作用◆Thestirruptookpartf
6、lexuralfordiagonalsectionanddecreasedadditionalσs;箍筋參與斜截面的受彎,使斜裂縫出現(xiàn)后縱筋應(yīng)力σ的增量減??;s◆Thestirrupdidnotinfluencecrackingloadandincreasebearingcapacityofdiagonal-compressionfailure.配置箍筋對(duì)斜裂縫開裂荷載沒有影響,也不能提高斜壓破壞的承載力,即對(duì)小剪跨比情況,箍筋的上述作用很?。粚?duì)大剪跨比情況,箍筋配置如果超過某一限值,則產(chǎn)生斜壓桿壓壞,繼續(xù)增加箍筋沒有作用。6.3有腹筋梁的受剪性能二、Fail
7、uremodeThemainfactorsthatinfluencefailuremodeofbeamwithshearreinforcementare:ρsvλandAnAsvsv1ρ==svbsbs剪跨比λ<11<λ<3λ>3配箍率無腹筋斜壓破壞剪壓破壞斜拉破壞ρsv很小斜壓破壞剪壓破壞斜拉破壞ρsv適量斜壓破壞剪壓破壞剪壓破壞ρsv很大斜壓破壞斜壓破壞斜壓破壞6.3有腹筋梁的受剪性能二、Failuremode破壞形態(tài)影響有腹筋梁破壞形態(tài)的主要因素有剪跨比λ和配箍率ρsvAnAsvsv1ρ==svbsbs剪跨比λ<11<λ<3λ>3配箍率無腹筋斜壓破壞剪壓
8、破壞斜拉破壞ρsv很小斜壓破壞剪壓破壞