论文部分内容阅读
以腊八斤特大桥11号主墩为原型，进行几何缩尺比例为1∶9.43的钢管混凝土(CFST)箱形叠合墩模型振动台试验，并结合空间杆系非线性有限元分析，开展强震作用下CFST箱形叠合墩的地震响应特性和地震破坏机理研究。结果表明：E2设计地震动作用下，缩尺模型和原型桥墩墩底塑性铰截面大部分处于受压状态，墩身表面未发现裂缝，结构处于弹性工作状态；地震动特性对CFST箱形叠合墩的地震响应有显著影响，9条经典地震波(PGA=0.05 g)中，Wenchuan-NS地震波作用下墩顶加速度响应和位移响应均达到最大，分别为最小地震响应工况的1.8倍和5.4倍；随着Wenchuan-NS地震波强度按照0.05 g的增量逐级增大，墩顶加速度响应和墩顶位移响应基本呈线性增加，且加速度动力放大系数基本保持在6左右；采用基于纤维梁柱单元的有限元模型计算结果与试验结果吻合较好，进一步开展的非线性时程分析可知，PGA=0.30 g时墩底潜在塑性铰区域外包混凝土受拉侧发生开裂，在PGA=0.75 g时受拉侧钢管开始屈服；与单向地震作用相比，双向地震作用下墩顶位移响应峰值增大约6%，墩底截面最大内力响应增大约4%，说明双向地震同时作用对CFST箱形叠合墩地震响应的影响较小，在进行CFST箱形叠合墩的地震反应分析时，可沿顺桥向和横桥向分别输入水平地震动。“,”Based on the prototype of the No.11 pier of Labajin Bridge, the shaking table tests was carried out for a CFST reinforced concrete pier with a hollow box section (CFSTRC-HBS pier for short) and with a geometric scale of 1∶9.43. Combined with the nonlinear finite element analysis of a spatial member system, the seismic response characteristics and failure mechanism of the CFSTRC-HBS pier under strong earthquakes were analyzed. The results showed that: under the action of E2-level earthquake, most of the plastic hinge sections at the bottom of the scaled model and prototype piers were under compression, and there were no cracks on the structural surface, i.e., the structures were in an elastic working state. The seismic response of the CFSTRC-HBS pier was significantly affected by the characteristics of ground motion. Among the nine classical seismic waves (PGA=0.05 g), the acceleration and displacement response of the pier top under the action of the Wenchuan-NS wave reached the maximum, which were 1.8 times and 5.4 times of the minimum seismic response, respectively. With the intensity of the Wenchuan-NS wave was increasing at an increment of 0.05 g, the acceleration response and displacement response of the pier top increased linearly and the acceleration dynamic-amplification factor maintained at about 6. The finite element results based on fiber beam-column elements were in a good agreement with the experimental results. The further nonlinear time history analysis showed that: when PGA was 0.30 g, the encasing concrete at the tension side of the potential plastic hinge area at the bottom of the pier cracked. When PGA was 0.75 g, the steel tube yielded, but the concrete did not crush at the compression side. Under the bilateral seismic actions, the peak displacement response of the pier top and the maximum internal force of the pier bottom increased by about 6% and about 4%, respectively, compared with the results of unilateral seismic action. It shows that the simultaneous action of bilateral earthquakes has little effect on the seismic response of CFSTRC-HBS piers. The horizontal ground motions in the longitudinal and horizontal directions can be input separately when analyzing the seismic response of CFSTRC-HBS piers.