基于一维Fick第二定律,采用DuraCrete规范中钢筋锈蚀初始时刻的概率预测模型,并基于概率统计的钢筋直径预测模型,计算不同龄期下RC结构中钢筋的锈蚀深度。基于修正斜压场理论并以锈蚀深度为单变量,对不同龄期下受压区锈胀开裂混凝土峰值应力进行计算;根据锈蚀深度对钢筋本构和Mander约束混凝土本构模型中相关参数进行了修正。于地震易损性模型中引入时间参数,建立含时间参数的RC结构地震易损性模型。最后,基于上述材料力学性能退化模型,采用基于力的纤维塑性铰模型,建立三层RC平面框架结构数值模型,并结合本文所提出的时变地震易损性模型,给出了三层平面RC框架0、5、10和15年龄期的易损性曲线和曲面。所提研究方法可用于既有RC框架结构生命周期内的抗震性能及损失预测分析。
Abstract
In this paper, the time-dependent fragility model is developed for corroding reinforced concrete (RC) frame. The developments represent a merger between a probabilistic model for chloride-induced corrosion and a time-dependent corrosion rate, and previously developed fragility model for undamaged RC frames designed by Chinese code. The loss of the cross sectional area of reinforcement bars, reduction of the cover and core concrete strength are modified by the single-factor time-dependent corrosion rate. Considering the cracking and spalling in the compressed concrete of compression zone caused by reinforcement corrosion, the modified compression-field (MCF) is used to predict the time-dependent compressed concrete strength. Finally, we employ SeismoStruct to obtain fragility estimates for the example frame based on the probabilistic models presented above. Three combined parameters (loss of the cross sectional area of reinforcement bars, reduction of the cover and core concrete strength) as a consequence of corrosion effects were calculated as a function of the corrosion rate for four different time periods (i.e., non-corroded (t=0), 5, 10and 15 years). The time-dependent fragility curves of three-floor RC frame in four ages corresponding to different performance levels are depicted by the IDA method based on the SeismoStruct. This method may be employed for the prediction of service-life and life-cycle cost analysis of RC frame structures.
关键词
氯离子 /
RC框架结构 /
IDA方法 /
地震易损性分析 /
多龄期 /
SeismoStruct
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Key words
chloride /
RC frames /
IDA method /
seismic fragility analysis /
multi-age /
SeismoStruct
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参考文献
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脚注
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