非规则多跨连续梁桥横向地震碰撞效应研究

为了探究非规则多跨连续梁桥的横向地震碰撞问题,提高同类桥梁的防震减灾能力,以广东潮安韩江大桥为研究对象,建立了考虑减隔震支座非线性与桩-土相互作用的横向碰撞计算模型,分析了横向碰撞特征及其对结构地震反应的影响,针对接触刚度与初始间隙进行了参数分析,并对橡胶垫片的减碰效果及其厚度的影响进行了探讨。结果表明:(1)横向碰撞可以减小梁墩相对位移,但会产生较大的碰撞力从而增加桥墩受力,并使各墩地震力分布更不均匀;(2)接触刚度的增加虽然可以减小梁墩相对位移,但当刚度值较大时梁墩相对位移的减幅趋缓,过大的刚度取值反而会引起桥墩过大的内力;(3)初始间隙的影响有一定的不确定性,但总体而言初始间隙较小时碰撞力与桥墩受力较大;(4)橡胶垫片可显著减小碰撞力与墩底弯矩,在工程条件允许时可适当增加垫片厚度。

Study on Transverse Pounding Effects of Irregular Multi-span Continuous Girder Bridges during Earthquakes

In order to improve the earthquake disaster prevention and mitigation capabilities of multi span continuous girder bridge, the transverse pounding effects of this type of bridge during earthquakes was studied. Taking Hanjiang River Bridge in Chao''an of Guangdong Province as a research object, the seismic transverse pounding calculation model was established. The nonlinearity of the seismic isolation bearings and the interaction between piles and soil were also considered in this model. On the basis of the proposed numerical model, the characteristics and the effects of transverse pounding on seismic responses of the bridge structures were first presented. Then a parametric analysis was conducted on the key factors of the contact stiffness and the initial gap between the girder and the retainer. Finally, the pounding mitigation method of rubber bumpers was suggested and the thickness effect of the bumpers was discussed. The results indicate that: (1) the transverse pounding can reduce the relative displacement between the girder and the piers, but at the same time the internal forces of the piers increase and the difference of seismic force between the piers turns out to be even bigger; (2) the increase of the contact stiffness causes a decrease of the relative displacement between the girder and the piers, but an excessive stiffness value will give rise to great internal forces in the piers; (3) the effects of the initial gap have some uncertainty, but in general, the pounding forces and the piers'' internal forces are larger when the initial gap is getting smaller; (4) rubber bumpers can significantly reduce the pounding force and the bending moments at pier bottoms, and it is suggested to appropriately increase the thickness of bumpers in compliance with other project conditions.