水平双向荷载作用下FRP约束RC矩形空心桥墩抗震性能试验

Seismic Performance Test on FRP Confined Bridge Piers with Rectangular Hollow Section Under Horizontal Bidirectional Loading

为了研究水平双向地震作用下纤维增强复合材料(FRP)约束钢筋混凝土(RC)空心桥墩的抗震性能,对10个FRP约束RC矩形空心桥墩进行了水平双向拟静力试验。通过分析不同试验空心墩的破坏形态、抗震性能参数和FRP有效拉应变,研究了长细比、壁厚、轴压比、FRP加固参数和加固方案对其破坏形态和抗震性能的影响,基于FRP拉应变试验结果和现有FRP有效拉应变计算模型,确定了影响FRP有效拉应变的主要参数,并提出了水平双向荷载作用下约束矩形空心桥墩的FRP有效拉应变计算公式。结果表明:FRP约束空心桥墩塑性铰区,可明显改善空心墩的耗能、极限变形和延性;提出的公式计算值与试验结果吻合较好。

In order to evaluate seismic performance of fiber reinforced polymer （FRP） confined reinforced concrete （RC） bridge piers with hollow section under horizontal bidirectional earthquake action, the horizontal bidirectional quasi-static test was carried out on 10 FRP confined RC performance bridge piers with rectangular hollow section. The failure modes, parameters and effective FRP tension strain of specimens were analyzed. The seismic effects of slenderness ratio, wall thickness, axial compression ratio, FRP confining parameters and strengthening plans on failure mode and seismic performance of specimens were studied. Based on experimental results and present computation models of effective FRP tension strain, the main influencing parameters for effective FRP tension strain were determinated. And an improved FRP effective tension strain formula was presented for FRP confined bridge piers with hollow section under horizontal bidirectional earthquake action. The results show that dissipated energy, limitdeformation and ductility of confined hollow section bridge piers are improved by FRP confining within plastic hinge region~ and the calculated FRP effective ultimate tension strains obtained by the new formula are well agreed with experimental results.