外包钢套加固震损双层高架桥框架式桥墩地震损伤分析与评估

Seismic damage analysis and evaluation of seismic⁃damaged double⁃deck viaduct frame piers strengthened by enveloped steel

为了对外包钢套加固震损双层框架式桥墩的地震损伤进行分析与评估,基于已有试验,应用OpenSees开放平台,以损伤指数折减材料性能参数模拟地震损伤,建立了双层框架式桥墩非线性有限元模型,对其进行低周往复加载,对比模拟与试验得到的滞回曲线和骨架曲线,验证了所建模型的可行性。采用Pushover分析方法,结合能力谱法求得4榀双层框架式桥墩试件在不同地震烈度下的性能点以及层间位移角,基于改进的Park-Ang损伤模型对桥墩试件的地震损伤进行分析。研究表明:当遭遇8度地震时,试件FP-2和试件FP-3最大层间位移角相对原型对比试件FP-0分别减小了26.4%和22.5%;当遭遇9度地震时,分别减小了26.5%和22.2%;当遭遇6度和7度地震时,各试件基本完好或造成轻微损伤;当遭遇8度和9度地震时,原型对比试件FP-0处于重度损伤,试件FP-2和试件FP-3均处于中度损伤,说明震损加固试件的损伤程度相较于原型对比试件均得到不同程度的减小。

In order to analyze and evaluate the seismic damage of seismic⁃damaged double⁃deck frame piers strengthened by enveloped steel,based on existing experiments,nonlinear finite element models of double⁃deck frame piers were built and the seismic damage was simulated by calculating the damage index to reduce material properties on the open platform OpenSees,the low cyclic loading analysis was performed to verify the feasibility of the proposed models by comparing the hysteresis curves and skeleton curves between simulation and tests.The performance points and the inter⁃story drift angles of four double⁃deck frame piers under different earthquake intensities were obtained by the pushover analysis method combined with the capability spectrum method,and the seismic damage of the piers was analyzed based on the improved Park⁃Ang damage model.The results show that:comparing with the contrast prototype specimen FP⁃0,the maximum inter⁃story drift angles of specimen FP⁃2 and FP⁃3 decrease by 26.4%and 22.5%and 26.5%、22.2%,respectively,when subjected to seismic precautionary intensity 8,seismic precautionary intensity 9,respectively;All specimens are basically intact or slightly damaged when subjected to seismic precautionary intensity 6 and 7.When subjected to seismic precautionary intensity 8and 9,contrast prototype specimen FP⁃0 is severely damaged,while the specimen FP⁃2 and FP⁃3 are moderately damaged.The study indicate that the damage degree of the seismic⁃damaged reinforced specimens are reduced to different degrees compared with the contrast prototype specimen.