带延性增强型节点的屈曲约束支撑钢框架的抗地震倒塌能力

Seismic Collapse Resistance Capacity of Buckling-Restrained Braced Steel Frame with Ductility-Enhanced Joints

地震作用下屈曲约束支撑钢框架结构的损伤分布通常是不均匀的,一旦梁柱节点或局部构件发生破坏,屈曲约束支撑的高延性就不能得以完全体现,且结构的局部失效和薄弱层的产生也容易导致结构倒塌。文中提出了两种改进型梁柱延性节点方案,将其应用于屈曲约束支撑钢框架结构中,使结构整体延性、延性节点和构件局部延性相互协调,形成高延性结构。首先,建立了屈曲约束支撑-延性节点钢框架结构的有限元分析模型,并对模型的准确性和可靠性进行验证;然后,采用增量动力分析方法,分析了屈曲约束支撑钢框架结构整体延性变化对结构体系抗地震倒塌能力的影响;最后,基于倒塌裕度比对结构体系抗倒塌能力进行评价。结果表明:与刚性节点结构相比,采用狗骨节点、上翼缘连接节点的屈曲约束支撑钢框架结构的整体延性增加,结构倒塌裕度比增大,结构抗地震倒塌能力提高。

Under the actions of earthquakes, the damage distribution of Buckling-Restrained Braced Steel Frames(BRBFs) is usually not uniform. Once the beam-column joints or other components of BRBFs are destroyed, the high ductility of the buckling-restrained braces cannot be fully achieved. The local failure and the weak stories of BRBFs would cause the structures to collapse. Therefore, this paper proposed the scheme of two improved ductile beam-column joints and applied it in the BRBFs to achieve the high ductility by coordinating the global ductility of the structure and the local ductility of the ductile joints and members. Firstly, the finite element models of the BRBFs with ductility-enhanced joints were established, and the accuracy of the numerical model was verified.Secondly, the incremental dynamic analysis method was used to analyze the influence of the global ductility on the seismic collapse capacity resistance of the structural systems. Finally, the seismic collapse capacity of the structural system was evaluated based on the Collapse Margin Ratio(CMR). The results show that, compared to the BRBFs with rigid connections, the global ductility of BRBFs with the Reduced Beam Section(RBS) connections and the Top-Flange Beam Splice(TFBS) connections increase gradually. The CMR and the seismic collapse resistance capacity of BRBFs are improved with the increment of structural global ductility.