Fragility Analysis of RC Frame Structures Based on Equivalent Linearization Method of SDOF System
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摘要: 通过有限元方法进行非线性动力时程分析获取解析的易损性曲线,计算量大且耗时。本文采用一种简化的计算方法,即基于单自由度的等效线性化模型,对钢筋混凝土框架结构进行地震易损性分析,并研究了该方法在结构高度上的适用性。通过选用5种典型的等效线性化模型对3栋不同高度的钢筋混凝土框架结构进行增量动力分析(IDA),得到了不同高度的结构在不同强度地震作用下结构的反应和易损性,并与OpenSees程序的计算结果进行对比,研究了等效线性化模型应用于RC框架结构易损性分析在高度上的适用性。分析结果表明:对于10层及以下的框架结构,基于单自由度的等效线性化模型在结构地震易损性分析中具有较好的适用性;对于更高层数的结构,由于高阶振型反应对整体结构反应的影响增大,基于单自由度等效线性化模型的易损性分析结果会出现明显的偏差。Abstract: Obtaining the analytical fragility curves through nonlinear dynamic time history analysis of FEA model is computationally intensive and time-consuming. In this paper, we used a simplified calculation method, namely the equivalent linearization method based on single degree of freedom, to analyze the seismic vulnerability of reinforced concrete frame structures and the applicability of this method for structures with different heights. The incremental dynamic analysis (IDA) for three reinforced concrete frame structures with different heights was carried out by using five typical equivalent linearization methods. The response and vulnerability of structures with different heights under different earthquakes were obtained. Compared with the results of OpenSees program, the applicability of the equivalent linearization method to the vulnerability analysis of RC frame structure is investigated. The result shows that for RC structures with height less than 10 stories, the equivalent linearization method based on single degree of freedom has good applicability for structural seismic vulnerability prediction. For higher structures, the influence of the high-order mode response on the overall structural response increases and the vulnerability analysis result based on the single-degree-of-freedom equivalent linearization method shows a significant deviation.
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Key words:
- RC frame structure /
- Equivalent linearization /
- Single degree of freedom /
- IDA /
- Fragility
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表 1 柱尺寸及配筋
Table 1. Sizes and reinforcement of columns
5层结构1层 2层 3~5层 500×500 mm 500×500 mm 500×500 mm
10层结构1~3层 4~5层 6~8层 9~10层 700×700 mm 700×700 mm 650×650 mm 650×650 mm
15层结构1层 2~7层 8~15层 700×700 mm 700×700 mm 650×650 mm 表 2 对数回归分析的参数结果
Table 2. Results of parameters from logarithmic regression analysis
层数 方法 a b $\beta $ 5
层R&H 0.83676 −4.0223 0.4665 退化 0.82756 −4.0423 0.4591 G&S 1.0745 −3.4258 0.6621 Kowalsky 1.0226 −3.5449 0.6149 Iwan 0.92018 −3.7250 0.5102 OpenSees 1.0078 −3.7162 0.4922 10
层R&H 0.89648 −4.2811 0.6235 退化 0.88171 −4.3166 0.5990 G&S 0.99393 −3.9680 0.7445 Kowalsky 0.96367 −4.0314 0.7292 Iwan 0.93816 −4.0919 0.6768 OpenSees 0.97903 −4.0231 0.4738 15
层R&H 0.92646 −4.5607 0.6187 退化 0.91607 −4.5822 0.6051 G&S 0.99907 −4.3595 0.7181 Kowalsky 0.97238 −4.3966 0.6967 Iwan 0.94396 −4.3783 0.7116 OpenSees 0.90681 −4.0942 0.4959 表 3 结构破坏状态对应的最大层间位移角
Table 3. The maximum inter-story drift ratio corresponding to the damage states of the structure
破
坏
状
态轻
微
破
坏中
等
破
坏严
重
破
坏
倒
塌层间位移角$\theta $ 0.002 0.005 0.01 0.02 -
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