无黏结预应力带耗能钢筋预制节段拼装桥墩抗震性能研究

摘要

运用美国太平洋地震工程研究中心开发的OPENSEES程序,采用纤维梁柱单元建立无黏结预应力带耗能钢筋预制节段拼装桥墩模型,进行拟静力加载过程分析,研究预应力度、轴压比、普通钢筋和预应力筋配筋率等参数对墩柱抗震性能的影响.结果表明:随着预应力度的提高,桥墩屈服力提高,但对水平承载力影响较小;预应力和上部结构恒载总的轴压比为20%～30%时,桥墩具有较高的水平承载力和等效阻尼比;预应力筋配筋率为0.20%～0.50%时,桥墩具有较稳定的水平承载力和耗能能力,增大预应力筋配筋率,桥墩等效阻尼比降低;提高普通钢筋配筋率时,桥墩的屈服力、水平承载力、能量耗散和等效阻尼比均有显著提高,但残余位移增大.地震响应分析结果表明,增设耗能钢筋能提高节段拼装桥墩水平承载力;地震作用下桥墩破坏时,墩底剪力约为拟静力试验水平承载力的70%～90%,墩顶位移约为拟静力试验破坏位移的50%.%The model of unbonded prestressing precast segmental bridge piers with energy dissipation bars was set up utilizing fiber beam-column element with the OPENSEES program developed by the Pacific Earthquake Engineering Research Center in the U.S. to investigate the pseudo static test procedure. The parametric analysis about the influence of the prestressing level, axial compression ratio and prestressed tendon or conventional rebar ratio upon the earthquake response of the bridge piers and columns was carried out. The results show that raising prestressing level can increase the yield strength but has little effect on the ultimate lateral strength. A total axial compression ratio of 20 to 30 percent of prestressing and superstructure dead load contributes to higher lateral strength and larger equivalent damping ratio of bridge columns. The column has stable lateral strength and energy dissipation ability as the prestressing tendon ratio is between 0. 20 and 0. 50 percent. The equivalent damping ratio of the bridge piers will be decreased with the increase of tendon ratio. The yield strength, ultimate lateral strength, energy dissipation and equivalent damping ratio will be increased remarkably with the increase of conventional rebar ratio, but the residual displacement will also be increased. The seismic response analysis reveals that the lateral strength can be raised by adding conventional reinforcement in precast segmental bridge piers. The shear at the damage level of precast segmental bridge piers bottom under history excitation is approximately 70 to 90 percent of pseudo static test results. The ultimate displacement of the pier top is only about 50 percent of that in pseudo static tests.