提升抗连续倒塌能力的钢框架梁柱刚性节点设计理念与方法

以方钢管柱隔板贯通式节点为研究对象，为提高其抗连续倒塌性能，提出了采用改进型全螺栓连接和加固型栓焊连接的钢框架梁柱刚性节点设计方法。通过试验及有限元模拟分析，考察不同连接构造的节点在中柱失效工况下的性能。结果表明：改进型全螺栓连接构造能够延缓下翼缘断裂，使节点子结构在更大的变形下保持传力截面的完整性，弯曲机制和悬索机制提供的抗力能同时发展至较大的值；加固型栓焊连接构造保证下翼缘连接板件在焊接连接失效后继续有效传力，且使螺栓孔壁局部承压塑性破坏优先发生，传力截面在更大的变形下能保持其完整性，梁端轴力可达到全截面轴拉屈服承载力，悬索机制提供的抗力可充分发展。因此，改进型全螺栓连接构造与加固型栓焊连接构造可提高结构的抗连续倒塌能力，验证了设计方法的可行性。

Design philosophy and method of rigid beam-column joint of steel frames to improve structural resistance against progressive collapse

This paper presents a research on the RHS column joints with through-diaphragms. Design method of rigid beam-column joint of steel frames using the modified bolted connection and reinforced bolt-weld connection was proposed aiming at improving the structural resistance against progressive collapse. Laboratory tests and finite element analysis were carried out to provide insight into the behavior of the joints with different connection details under a central column removal scenario. The results demonstrate that the modified bolted connection can delay the fracture occurrence at the bottom flange. Therefore the section area can keep effective under larger deformation and catenary mechanism can be fully developed without completely losing the flexural resistance. The reinforced bolt-weld connection can make the bottom flange continue to transfer force effectively after the weld failure. In addition, the failure mode featured by localized bearing damage at the bolt bearing area develops preferentially, which is beneficial to delay of the reduction of the effective section area. Hence the axial force of the beam can develop to the value of full plastic strength and the joint can take full advantage of catenary mechanism. For that reason, the modified bolted connection and the reinforced bolt-weld connection are proved to have a better performance in terms of progressive collapse prevention. Furthermore, the feasibility of the design method is verified.