RC框架梁柱子结构抗连续倒塌性能不确定性分析

UNCERTAINTY ANALYSIS ON PROGRESSIVE COLLAPSE RESISTANCE OF RC BEAM-COLUMN SUBSTRUCTURES

  • 摘要: 近年来,结构的抗连续倒塌问题在国内外引起了广泛关注。RC框架作为实际工程中最常见的结构形式被广泛研究。然而,已有RC框架梁柱子结构的连续倒塌性能相关研究多基于确定性分析且主要针对静力拆除构件工况。该文基于OpenSees分别建立了典型RC框架梁柱子结构的静力和动力连续倒塌分析有限元模型,通过试验对比验证了模型的准确性。在此基础上,考虑结构截面几何属性、材料特性等不确定性因素,基于拉丁超立方抽样生成不同模型并分析了结构不确定性对RC框架梁柱子结构静力和动力抗连续倒塌性能的影响。参数不确定性分析结果表明:悬链线机制对RC框架梁柱子结构的抗连续倒塌性能十分重要;而以梁端转角达到0.20 rad作为RC框架梁柱子结构动力失效指标在一定程度上偏于保守。参数敏感性分析结果表明:纵筋屈服强度、极限强度为影响RC框架梁柱子结构抗连续倒塌能力的主要因素。

     

    Abstract: In recent years, the problem of progressive collapse of building structures has aroused widespread concern at home and abroad. As one of the most commonly used structure systems in engineering practice, the reinforced concrete (RC) frame structures have been widely involved in many existing progressive collapse studies. However, most of the studies were mainly based on deterministic and static analyses of column removal scenarios. In this study, the finite element (FE) model of a typical RC frame beam-column substructure is built based on OpenSees. Both static and dynamic progressive collapse analyses of the beam-column substructure are performed and validated against the experimental results. Furthermore, several structural models were generated for the uncertainty analyses by the Latin hypercube sampling method. The influences of various uncertainty factors are discussed, including the sectional geometries, material properties and so on. The results indicate that the catenary action plays a crucial role in RC frame beam-column substructures against progressive collapse. However, the use of 0.2 rad chord rotation as the failure index in the dynamic progressive collapse analyses is to a certain extent conservative. Moreover, according to the sensitivity analyses, the yield strength and ultimate strength of the longitudinal reinforcement are the major factors that affect the progressive collapse resistance of RC frame beam-column substructures.

     

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