既有混凝土梁桥加宽改造的时变可靠度分析

Time-variant Reliability Analysis for Widened Reinforced Concrete Girder Bridge

为了研究桥梁加宽后构件刚度劣化对新旧桥时变可靠度的影响,建立了混凝土构件在劣化环境下的可靠度计算模型。以一座钢筋混凝土梁桥为研究对象,在考虑新旧桥刚度劣化不一致的情况下,运用MATLAB软件分析了新旧桥时变可靠度指标的具体变化规律。研究结果表明:钢筋锈蚀会造成原桥主梁抗弯承载能力下降,承载力标准差上升,从而引起新旧桥主梁荷载横向分布系数以及变异系数发生变化,在新旧梁拼接缝处变化最为明显;桥梁加宽改造后,原桥时变可靠度指标上升,而新桥明显下降。

In order to study the inf luence of the stiffness degradation on after bridge widened the time-variant reliability of the new and old bridges,the reliability calculation model of the concrete members in the degradation environment was established.Taking a reinforced concrete girder bridge as the research object and considering the inconsistent stiffness deterioration of new and old bridges,the MATLAB software was used to analyze the specif ic variation laws of the time-variant reliability index of the new and old bridges.The results show that the steel corrosion decreases the bending capacity of the main girder in the original bridge,and the standard deviation of the bearing capacity increases synchronously,which change the load lateral distribution coeff icient and variation coeff icient of the girder in the new and old bridges,and the variation near the stitching seam is the most obvious.After the bridge is widened,the time-variant reliability index of the original bridge rises,while the index of new bridge drops signif icantly .