多维地震激励下人字形桥梁地震模拟振动台试验研究

为研究人字形桥梁在地震作用下的动力响应，以某人字形桥梁为原型，制作了一座相似比为1/20的模型桥梁，采用El-centro波对其进行了不同地震烈度的多维激励地震模拟振动台试验和有限元分析。研究结果表明：随着地震烈度的增加，模型结构自振频率降低阻尼比增大；桥墩墩顶顺桥向加速度响应基本不受竖向地震分量影响；计算桥墩墩底应变响应时进行水平双向地震激励即可满足要求；梁体跨中竖向加速度响应，主梁和分支梁间的伸缩缝宽度取值，伸缩缝处的碰撞响应等均与地震波输入维度有关。因此，对于人字形桥梁在进行抗震设计时应针对不同的设计目的对其进行选择性的多维地震激励。

Shaking table test of Y-shaped bridge under multi-dimensional excitation

In order to study sesimis response of Y-shape bridge under the earthquake, based on a existing Y-shape bridge, a scale 1/20 model of Y-shaped curved bridge was constructed, the El-centro waves was using to make a shaking table test with different earthquake intensity and multi-dimensional excitation. Besides, the finite element analysis were also been conducted for this model bridge. And the Research results show that when the earthquake intensity enhancing, the fundamental frequency of model bridge decreased greatly and the damping ratio increased. The longitudinal acceleration response of pier’s top has no influence with the vertical earthquake excitation. The horizontal direction earthquake excitation can meet with calculating the strain response at the bottom of the pier. When the vertical acceleration response of mid span, expansion joint width between main beam and branch beam and pounding response of expansion joint are analysed, all of them have relationship with seismic wave input dimension. Therefore, Y-shaped bridges should be whether conducted multi-dimensional excition or not in seismic design according to different design purpose.