中小跨度斜交连续梁桥的抗震体系研究

摘要:

中小跨度斜交连续梁桥普遍采用板式橡胶支座,在地震作用下,主梁与支座间容易发生滑动,同时主梁会发生平面内转动,落梁风险较大。本文以中等烈度区一座3跨斜交连续矮T梁桥为工程背景,建立板式橡胶支座支承的斜交桥有限元模型,采用非线性时程分析方法,进行地震反应特性分析,针对性地提出了板式橡胶支座(允许滑动)+钢阻尼器的组合减震体系,并对提出的减震体系做了位移控制效果分析。结果表明：在地震作用下,斜交桥中板式橡胶支座极易发生滑动,从而增大主梁地震位移并丧失自复位能力,但只要不发生主梁与桥台(挡块)的碰撞,主梁平面内转动的影响可以忽略不计；而板式橡胶支座+钢阻尼器的组合减震体系可以有效控制主梁纵横向位移、并限制主梁平面内转动。

Abstract:

Plate rubber bearings are widely used in medium and small span skew bridges. The main girder and bearings are prone to slide, and the main girder will rotate under the earthquake, so the risk of unseating is high. Based on a 3-span skew continuous T-shaped beam with low web bridge in medium intensity area, the finite element model of skew bridge supported by plate rubber bearings is established. The nonlinear time history analysis method is used to analyze the seismic response characteristics. The composite seismic system of plate rubber bearings (allowable sliding) + steel damper is proposed, then the displacement control effect of the proposed seismic system is analyzed. The results show that: the rubber plate bearings in the skew bridge are easy to slide under the earthquake, which leads to the loss of self-reset ability of the structure, the influence of the rotation of the main girder can be ignored as long as the collision between the main girder and the abutment does not occur, the composite seismic system of plate rubber support and steel damper can effectively control the displacement and limit the rotation of the main girder.