Numerical analyses of post-fire beam-column assemblies with WUF-B connections against progressive collapse

• Published in: Engineering failure analysis 2022-10, Vol.140, p.106502, Article 106502
• Main Authors: Guo, Zhan, Li, Zhihui, Xing, Zhiquan, Chen, Yu, Zheng, Zhiyang, Lin, Guixing
• Format: Article
• Language: English
• Subjects: Constructional measures; Numerical simulation; Parametric analysis; Progressive collapse; Reinforcement methods after a fire; WUF-B connections
• ISSN: 1350-6307; 1873-1961
• DOI: 10.1016/j.engfailanal.2022.106502

•A refined numerical simulation approach that considers material fracture was introduced.•An abundance of parametric studies was performed on beam-column assemblies.•Several suggestions on anti-collapse constructional measures were proposed.•Two typical reinforcement methods were presented to strengthen post-fire specimens. This paper presents the progressive collapse experiment efforts in beam-column assemblies with WUF-B connections after fire exposure. A refined numerical simulation approach that considers the damage and failure for ductile metals was introduced to understand the structural response of the post-fire specimens. The established numerical model could effectively simulate the failure patterns, key fracture phenomenon, load–displacement response, as well as strain evolutions of the specimens. Subsequently, an abundance of parametric studies was performed based on the validated numerical approach to investigate the effects of variable configurations of WUF-B connections on the progressive collapse resistant performance of the beam-column assemblies. It was demonstrated that the vertical resistance and deformability of the post-fire assemblies could be obviously improved by enlarging the shear plate thickness. However, the bolt preload exerted little influence on the structural behaviors of the post-fire assemblies under column removal scenarios. For the assemblies with WUF-B connections, increasing the end distance between the inner bolt hole and the middle column flange (namely, parameters a) as well as decreasing the vertical bolt hole spacing (namely, parameters c) could effectively enhance the vertical resistance and deformability of the specimens. On account of the remaining unchanged crack propagation and force transfer path of the specimen, the horizontal bolt hole spacing (namely, parameters b) negligibly influenced the structural response of the specimens. In the anti-collapse design of the assemblies with WUF-B connections, it was suggested to appropriately increase the values of parameters a and b, but properly reduce these of parameter c on the premise of meeting the designed bolt configurations, which was more conducive to the formation and development of the catenary actions. Eventually, two typical reinforcement methods used for the post-fire assemblies were also numerically studied and compared in terms of the structural behaviors of strengthening specimens against progressive collapse.