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多层RC框架底层中柱失效连续倒塌计算模型

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多层RC框架结构在底层中柱失效后,不平衡荷载由失效柱上方各楼层共同承担,其承载力相比单层框架会大幅提升.然而,由于缺乏系统的多层RC框架连续倒塌试验和数值模拟研究,失效柱上部各楼层的连续倒塌抗力机制尚不明确,既有研究中关于多层RC框架结构的抗连续倒塌承载力理论分析模型也十分有限.为此,首先依照中国规范设计了9座典型的RC框架结构,采用OpenSees开展了各框架在底层中柱失效时的连续倒塌分析,系统研究了各楼层梁的内力及应变分布,讨论了不同楼层的梁内连续倒塌抗力发展机制.在此基础上,结合单层RC框架梁柱子结构的连续倒塌承载力计算模型,依据各层梁的抗力贡献,建立了多层RC框架底层中柱失效的连续倒塌抗力计算模型,并与试验及数值模拟结果进行了对比验证.研究结果表明:①底层中柱失效后,多层RC框架首层梁存在显著的压拱机制和悬链线机制;②多层RC框架结构沿楼层高度方向布置不同尺寸构件时,截面尺寸变化的下部楼层梁会存在压拱受力机制;③除上述楼层外,其他楼层梁主要通过受弯机制提供连续倒塌抗力;④所提计算模型能较准确计算多层RC框架底层中柱失效时的抗连续倒塌承载力.
Analytical Model for Progressive Collapse of Multi-story RC Frame after a Ground-story Middle Column Removal
In a multi-story RC frame,when the ground-story middle column fails,the unbalanced load is borne by the stories above the failed columns,and the load-carrying capacity is significantly in-creased compared to a single-story frame.However,due to the lack of systematic experimental and nu-merical investigations on the progressive collapse resistance of spatial multi-story RC frames,the force mechanisms of the stories above the failed column for resisting progressive collapse are still un-clear.Moreover,there are few analytical models for quantifying the progressive collapse resistance of multi-story RC frame structures among existing studies.Therefore,9 typical multi-story RC frames are designed following the Chinese design codes and their progressive collapse behaviors under the ground-story middle column removal scenario are analyzed.The internal forces and strain develop-ments of the beams on each story are systematically analyzed.And the progressive collapse-resisting mechanisms of various stories in an RC frame are discussed.On this basis,the calculation model of single-story RC beam-column substructures is combined to establish the analytical model for quantify-ing the progressive collapse resistance of a multi-story RC frame after the ground-story middle column removal,by calculating the resistance contributions of different stories.The experimental tests and nu-merical simulations are compared with the calculated results to verify the accuracy of the proposed model.The results show that:(1)Following the removal of the column,significant compressive arch action and catenary action are observed in the ground story beams.(2)When components of varying di-mensions are arranged vertically within the RC frame,compressive arch action is observed in the low-er floor beams that experience a change in component size.(3)Apart from the aforementioned floors,beams on other floors generally exhibit progressive collapse resistance through flexural actions.(4)The proposed analytical model can provide a satisfying estimation of the progressive collapse resis-tance of a multi-story RC frame under the ground-story column removal scenario.

multi-story RC framesprogressive collapsenumerical simulationsstress mechanismcal-culation model

林楷奇、李道远、蔡亮

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福州大学土木工程学院,福建 福州 350116

可持续与创新桥梁福建省高校工程研究中心,福建 福州 350108

福建省土木工程多灾害防治重点实验室,福建 福州 350116

多层RC框架 连续倒塌 数值模拟 受力机制 计算模型

2024

防灾减灾工程学报
中国灾害防御协会 江苏省地震局

防灾减灾工程学报

CSTPCD北大核心
影响因子:0.529
ISSN:1672-2132
年,卷(期):2024.44(6)