基于限位索的简支梁桥地震防碰研究

Research on using cable restrainers to prevent collision between girders for simply supported bridges under strong earthquake

强震作用下,简支梁桥固定支座容易发生破坏导致相邻梁体和梁台间产生较大的相对位移,引发邻梁碰撞,造成梁体的损坏甚至落梁。本文以我国西部某典型4×30 m公路简支梁桥为工程背景,分析了4种不同地震动激励下的碰撞效应,并在梁体间和梁台间引入限位索,进行了防碰撞研究。结果表明:在峰值加速度为0.30 g的地震动激励下,固定支座均出现了剪坏现象,梁体和梁台间最大相近位移超过了邻梁间距,均发生了碰撞;限位索可以有效地避免梁体间碰撞现象的发生,但在实际选用限位索数量时,既要考虑防碰撞效果,又要防止限位索拉断现象。

Since the fixed bearings of simply supported bridge are liable to fail under strong earthquake, the relative displacement will be excessive to cause the collision between girders. Taking the 4 - 50 m highway simply supported bridge as a background engineering, the collision effects subjected to four kinds of seismic ground motions are analyzed. Further, cable restrainers are set up between the girders to prevent the collision. The results show that the maximum relative displacements exceed the initial gaps between girders and cause the collision due to the failure of the fixed bearings under seismic ground motions of the peak acceleration 0.30 g. The restrainers can effectively prevent the collision. The number of the cables should be decided by both the collision prevention effect and avoiding the cables fracture.