螺旋箍筋约束高强钢筋浆锚搭接单向拉伸试验研究

Uniaxial tension experimental study on the grouting-anchoring overlap-joint of high strength steel bar restrained by spiral stirrups

设计制作了9组共78个螺旋箍筋约束高强钢筋浆锚搭接试件,通过单向拉拔试验,研究了其破坏机理以及钢筋强度、混凝土强度、钢筋搭接长度、螺旋箍筋形式等因素对搭接性能的影响。结果表明:未配置螺旋箍筋的浆锚搭接试件主要破坏模式为混凝土的锚固失效开裂,且其承载力和强屈比随钢筋搭接长度的增加逐渐增加;配置螺旋箍筋后,钢筋搭接长度大于0.80l_(ab)(l_(ab)为钢筋基本锚固长度)时,试件主要破坏模式为钢筋受拉屈服且其极限承载力较稳定;钢筋搭接长度为0.56l_(ab)时,试件端部混凝土出现开裂,部分试件的极限承载力显著降低。建议实际工程中钢筋直径为16mm时,螺旋箍筋约束高强钢筋浆锚搭接的搭接长度取0.80l_(ab);其他直径钢筋可参考该搭接长度并经过试验验证后应用。

Nine groups of seventy-eight specimens of grouting-anchoring overlap-joint of high strength steel bar restrained by spiral stirrups were designed and fabricated.The failure mechanism and the influence of steel bar strength,concrete strength,lapping length of steel bars and spiral stirrup type on the lapping property were investigate by uniaxial tension tests.The results show that the main failure mode of the specimens without spiral stirrups was the anchorage failure and cracking of concrete,and the bearing capacity and ductility ratio increase with the increase of lapping length of steel bars.The main failure mode of specimens restrained by spiral stirrups is steel bar tensile yield,when the lapping length is over 0.80l_(ab)(l_(ab)is the basic anchorage length of the steel bar),and the bearing capacity of restrained specimens is very stable.When the lapping length of steel bars is 0.56l_(ab),concrete crackes at the end of the restrained specimens,and the bearing capacity of some specimens decrease significantly.It is suggested that when the diameter of steel bar is 16mm in practical engineering,the lapping length of high strength bars should not be less than 0.80l_(ab).The suggested lapping length can be refereed for high strength bars with other diameters,and be verified by the test before application.