碳纤维-箍筋约束倒角矩形混凝土柱的轴压性能

AXIAL COMPRESSIVE BEHAVIOR OF CFRP-STIRRUP CONFINED ROUNDED RECTANGULAR CONCRETE COLUMNS

对24个碳纤维-箍筋约束倒角矩形混凝土柱进行了轴压试验。试验表明,碳纤维与箍筋对核心混凝土形成双重的约束机制,两者相互补充,有效提高了混凝土柱的承载能力和变形能力,其箍筋保证了FRP断裂后的残余承载力及延性;FRP-箍筋约束倒角矩形混凝土柱的轴压性能与纤维层数及试件倒角半径参数紧密相关,倒角半径的增大显著改善了其轴压力学性能,对于相同FRP包裹层数,倒角半径越大,力学性能提高效果越好,在倒角半径相同的条件下,增加FRP层数可有效提升约束柱的承载能力及变形能力;结合试验结果,在圆柱FRP-箍筋约束混凝土的极限应力计算模型的基础上,引入单一材料约束混凝土矩形柱的有效约束系数,提出了FRP-箍筋约束倒角矩形混凝土柱的承载力计算模型。

Axial compression tests were carried out on 24 carbon fiber polymer-stirrup confined rectangular concrete columns with chamfering. The test shows that CFRP and stirrups form a dual constraint system for the core concrete,which complements each other. It effectively improves the bearing capacity and deformability of the concrete column in which stirrups ensure the residual bearing capacity and ductility after the fracture of FRP. The axial compression performance of FRP-stirrup rectangular concrete columns with chamfering is closely related to the number of FRP layers and the chamfering radius of specimens. Increasing the chamfering radius can improve the properties of the concrete column significantly. With the same layers of FRP,the bigger the chamfering radius is,the better the performance will be. Besides,increasing the number of FRP layers can effectively improve the bearing capacity and deformation capacity of the confined concrete column with identical chamfering radius. Combined with the test results,the bearing capacity calculation model of CFRP-stirrup confined rectangular concrete columns with chamfering is proposed by considering the effective constraint coefficient of the rectangular concrete column,and on the basis of the ultimate stress calculation model of confined circular concrete columns.