基于加权秩和比法的隔震梁桥失效模式研究

Failure Mode of Isolated Beam Bridge by Weighted Rank Sum Ratio Method

为了综合评价桥梁在地震作用下失效模式的信息,考虑地震动中存在的不确定性影响,对实际工程中的某6跨隔震连续梁桥的失效模式进行了分析.基于IDA法,选用16条足够反映地震动中存在的不确定性且PDA分布在一个较宽强度范围内的地震动,对桥梁中支座、桥墩墩底这两个最容易失效的部位分别基于位移和修正的Park-Ang损伤理论判断其失效,引用加权秩和比法综合了16条地震动作用下的桥梁失效模式的评价信息,分析给出具有统计意义的失效模式,并找出了桥梁的最弱失效模式.研究结果表明:该隔震连续梁桥的失效模式为该桥梁中墩的隔震支座先失效,然后是桥梁过渡墩支座失效,最后是边墩底部和边墩的支座失效;桥梁的最弱失效模式为桥梁所有隔震支座先失效,其次是边墩底部失效,然后是中墩失效,最后是过渡墩失效.

To e s t ima te the fai lure modes of seismical ly isolated cont inuous girder br idges,a p ra c t ic a l engineering with six spans was analyzed considering the uncertainty of seismic ground motions. Sixteen ground motion records were selected to be used in IDA method ’ which could provide sufficient accuracy of seismic analysis demands, and the PGA of these records were distributed in a wide range. Bearings and the bottom of piers were the most vulnerable parts of the bridge, of which failure criteria were estimated by displacement and modified Park-Ang damage theory ’ respectively. And weighted rank sum ratio method was adopted to analyze evaluation information of the bridge under sixteen ground motion records, th e n th e s ta t is t ic a l ly signif ican t fa i lu re modes an d th e we ak e st fa i lu re mode of the bridge were identified. The results show that the final failure mode of the isolation continuous girder bridge arises at the isolation bearings of the middle piers, a t th e isolation be a r in g s of th e trans i t ion piers, and at the bottom of side piers and bearings. The weakest fai lure mode of this bridge happenswith all isolation bearings cease to be effective first, then it comes to the bottom of the side piers and the middle piers, and finally the transitional piers.