不同设计配筋下大偏压RC柱承载力抗震可靠度

摘要

To explore the influence laws of random eccentricity on seismic capacity reliability of RC columns with design reinforcements,the failure function and the formula of the influence coefficient of reinforcement are obtained and expressed by multiple normalized design parameters with an analytical method.Based on the requirements on column reinforcement in codes,the variation laws of the influence coefficient of reinforcement are analyzed with multiple design parameters(e.g.load effect ratios) within common ranges.Considering the random properties of eccentricity and the prescribed probability models of horizontal earthquake action,vertical gravity load,concrete strength and steel strength,etc.,the seismic capacity reliability is obtained for RC columns with tension failure by the Monte Carlo method.The results indicate that the variations of the influence coefficient of reinforcement are large for different combination cases of design parameters;the seismic capacity reliability is improved less with the increase of reinforcement for the columns with a smaller influence coefficient of reinforcement;the reliability is improved dramatically with the increase of reinforcement for the columns with a larger influence coefficient of reinforcement.%为研究偏心距随机特性对不同设计配筋下RC柱承载力抗震可靠度的影响规律,采用解析方法,推导了以多个无量纲化设计参数表达的大偏压RC柱失效方程和配筋影响系数计算式.考虑规范中的柱配筋率要求,分析了荷载效应比值等设计参数在常用取值范围内时配筋影响系数的变化规律.结合已有的水平地震作用、竖向重力荷载、混凝土强度和钢筋强度等参数的概率模型,并考虑偏心距的随机特性,采用Monte Carlo方法进行了大偏压RC柱可靠度分析.结果表明:不同设计参数组合下大偏压RC柱配筋影响系数的变化离散性较大;当配筋影响系数较小时,增加配筋对大偏压RC柱可靠指标的改善作用不大;当该系数较大时,增加配筋对可靠指标的提升效果较明显.