钢筋锈蚀与余震对RC框架结构地震损伤与易损性的影响分析

EFFECTS OF CORROSION AND AFTERSHOCK ON STRUCTURAL DAMAGE AND FRAGILITY OF REINFORCED CONCRETE FRAME STRUCTURES

为量化钢筋锈蚀与余震对钢筋混凝土结构抗震性能的影响,选取两栋按我国现行规范设计的中国东南沿海地区钢筋混凝土框架结构为研究对象,考虑未锈蚀和由低到高三种不同锈蚀率(5%、10%和15%)的四种工况,采用真实主余震序列作为输入,选取Park-Ang损伤指数作为结构损伤指标,开展了主余震序列作用下的未锈蚀与锈蚀钢筋混凝土框架结构的地震损伤评估与易损性分析。计算结果表明:锈蚀率的提高加剧了主余震序列作用下的结构累积损伤,其增长率最大可超过50%。由钢筋锈蚀单一因素引起的结构损伤在主余震累积损伤中的占比最高可超过30%。此外,钢筋锈蚀因素会导致结构的主余震易损性曲线发生显著提升。当锈蚀率较大时,钢筋锈蚀对结构易损性的影响与余震对结构易损性的影响相接近。钢筋锈蚀和余震两个因素的耦合作用会使结构的易损性水平发生更为显著的提升。因此,十分有必要在既有钢筋混凝土结构抗主余震性能评估中考虑钢筋锈蚀因素的影响。

To evaluate the effects of corrosion and aftershock on structural seismic resistance.Two seismic designed reinforced-concrete frame buildings located in a coastal city were selected for study.Four corrosion conditions were considered,i.e.,uncorroded and corrosion ratios of 5%,10%and 15%.A set of 662 mainshockaftershock sequences were taken as the inputs for time history analysis.Then the damage analysis and fragility assessment were conducted to the corroded and uncorroded buildings subjected to mainshock-aftershock sequences.Results show that the increment of corrosion ratio exacerbates structural cumulative damage under mainshock-aftershock sequences.The increment ratio of the structural cumulative damage is even over 30%.The corrosion effect can lead to an increase in fragility curves,and the influence of the corrosion effect on mainshock fragility curves under heavy corrosion condition is close to that under aftershocks.The coupling effect of corrosion and aftershock can cause a significant elevating in mainshock fragility curve.Therefore,it is necessary to consider the effect of corrosion in seismic performance assessment subjected to mainshock-aftershock sequences.