Performance analysis of novel double web V-bending angle-steel connections against progressive collapse

This study introduces a double web V-bending angle-steel connection (DWVAC) as a novel solution to overcome the ductility limitations of traditional double web angle-steel connections, specifically catering to the requirements of the tying force strategy. The DWVAC's anti-progressive collapse performance is analyzed using validated numerical models, and its working mechanism during progressive collapse conditions is revealed through theoretical analysis. The design process for the DWVAC is also presented, providing a comprehensive understanding of its structural performance. The study reveals that the DWVAC operates in two stages: the micro-bending stage and the catenary stage. During the micro-bending stage, the DWVAC exhibits minimal load-bearing capacity, relying primarily on axial forces in the subsequent catenary stage. Ultimately, the DWVAC fails due to rupture of web V-bending angle-steels. By understanding the DWVAC mechanism, the geometrical parameters of the V-bending angle-steel can be customized to achieve the recommended 0.20 rad ultimate rotation while satisfying various deformation requirements within a 0.30 rad ultimate rotation. The study further investigates six key parameters of the V-bending angle-steel, providing a calculation formula for its ultimate deformation based on multiple nonlinear fitting of numerical simulation analysis results. Notably, the numerical simulation analysis recommends that parameter g should not exceed 3.5 times the bolt hole diameter, and the recommended range for beam length is between 8 and 20 times the beam depth. The theoretical design process for the DWVAC is proposed, and numerical examples considering different beam and column sections are analyzed to demonstrate the rationality of the DWVAC's design process.