承压状态下网状箍筋约束PC管桩抗震性能试验

Seismic performance of prestressed concrete pipe piles with meshed stirrup subjected to axial compression force

摘要:

与普通混凝土桩相比,预应力混凝土管桩（PC管桩）抗震性能差,为改善其性能提出一种新型网状箍筋约束的PC管桩.通过对2组共4根PC管桩试件在不同轴压比下的拟静力试验,研究配筋形式、轴压比对其抗震性能的影响,其中一组为新型网状箍筋约束另一组为普通螺旋配箍,各组轴压比分别为0.3、0.5.详细记录试验破坏过程,得到试件的滞回曲线、骨架曲线、承载力、变形能力,刚度退化曲线和耗能能力等.试验结果表明:各试件均产生受弯破坏,延性系数在2.99~3.96之间；网状箍筋约束试件耗能能力强,其滞回环较螺旋配箍试件饱满；试件承载力、延性以及耗能能力受轴压比影响较大,轴压比越大,承载力越大,延性及耗能能力越差.给出了网状箍筋约束PC管桩正截面承载力计算公式,同时,对高轴压比作用下预应力混凝土管桩正截面抗弯承载力公式提出了修改建议.

Abstract:

Prestressed concrete (PC) pipe pile has poor seismic performance compared with ordinary concrete piles. To improve the performance, a new type of mesh-constrained PC pipe pile is proposed. Through the quasi-static test of four PC pipe pile specimens, which are divided into two groups under different axial compression ratios, effects of reinforcement form and axial compression ratio on their seismic performance were investigated. One group had a new type of meshed constraint and the other had common spiral constraint. The axial compression ratios of each group were 0.3 and 0.5 respectively. The failure process was recorded in detail, and the hysteresis curve, skeleton curve, load-bearing capacity, deformation ability, stiffness degradation curve and energy consumption capacity of the test specimens were obtained. Results show that all test specimens were subjected to flexural failure, and the ductility factor was between 2.99 and 3.96. The meshed constrained test specimens had large energy consumption, and its hysteresis loop was fuller than the spiral constrained specimens. The load-bearing capacity, ductility and energy dissipation capacity of the specimens were greatly affected by the axial compression ratio. The larger the axial compression ratio, the greater the load-bearing capacity and the worse the ductility and energy dissipation capacity. A formula of flexural capacity of the PC pipe piles with meshed constrain stirrups is proposed and the formula of the PC pipe piles subjected to the high axial compressive ratio is modified.