不锈钢筋-FRP筋混合配筋预制节段桥墩抗震性能研究

Study on seismic performance of precast segmental pier columns with stainless steel and FRP reinforcements

为解决沿海环境中钢筋易锈蚀的问题,结合节段拼装桥墩的快速建造技术,设计了一种配置2304不锈钢筋和GFRP筋的混合配筋形式的节段预制拼装桥墩.通过ABAQUS有限元软件建立了混合配筋桥墩的数值仿真模型,分析了其在低周往复荷载作用下的滞回性能,并通过与试验结果对比验证了有限元模型的正确性.采用该有限元模型进一步探究了GFRP筋的无粘结段长度比例、轴压比、剪跨比对节段拼装桥墩抗震性能的影响.数值计算结果表明:随着GFRP筋无粘结段长度减小,节段拼装桥墩的承载力提高.无粘结段长度越长,GFRP筋的局部应力越小,位移延性越好,但是墩柱的耗能变小.建议GFRP筋的无粘结段长度在40%~80%之间,以保证桥墩具备良好的抗震性能,避免GFRP筋应力集中发生突然断裂.通过增加轴压比,试件承载力增幅不明显;试件剪跨比从4.5增大为9.5,试件水平承载力降低63%.为后续后张预应力混合配筋桥墩的抗震性能试验研究奠定基础.

In order to solve the problem that reinforcement is easy to rust in coastal environment,combined with the rapid construction technology of segmental assembled pier,a segmental prefabricated assembled pier with 2304 stainless steel reinforcement and GFRP reinforcement is designed.The numerical simulation model of hybrid reinforced pier is established by ABAQUS finite element software,and its hysteretic performance under low cyclic load is analyzed.The finite element model,the correctness of which is verified by comparing with the test results,is used to further explore the effects of unbonded section length,axial compression ratio and shear span ratio of GFRP reinforcement on the seismic performance of segmental assembled piers.The numerical results show that the bearing capacity of segmental assembled piers increases with the decrease of the length of unbonded GFRP reinforcement.The longer the length of unbonded section,the smaller the local stress of GFRP reinforcement and the better the displacement ductility,but the energy consumption of pier column becomes smaller.It is suggested that the length of unbonded section of GFRP reinforcement should be between 40%~80%,so as to ensure that the pier has good seismic performance and avoid sudden fracture due to stress concentration of GFRP reinforcement.By increasing the axial compression ratio,the increase of the bearing capacity of the specimen is not obvious;the shear span ratio of the specimen increases from 4.5 to 9.5,and the horizontal bearing capacity of the specimen decreases by 63%.This study lays a foundation for the subsequent experimental study on the seismic performance of post tensioned prestressed composite reinforced piers.