Evaluation of progressive collapse resistance performance of steel OMF with WCPF connections

Abstract

A welded cover plated flange (WCPF) connection, which is a pre-qualified connection detail improving a weak weld access hole and the ductility of a welded unreinforced flange-bolted web (WUF-B) connection, has a simple and efficient advantage in construction. In this study, a new modelling approach of the WCPF connection by employing 1-D element was proposed for the evaluation of progressive collapse resistance capacity performance. The model was developed by substituting the average width of trapezoidal shapes of cover plates welded to the top and bottom flanges and by assessing the equivalent flange thickness based on the moment of inertia. The proposed model was verified through comparisons with experimental and 3-D numerical results, showing discrepancy within 5.7%. To evaluate the performance of the WCPF connection, a prototype structure was adopted from the previous study for the appraisal of the WUF-B and reduced beam section (RBS) connections. The alternative load path method was performed using an energy-based approximate analysis considering the dynamic effect of sudden column loss. The performance of the structure was evaluated in terms of structural robustness and sensitivity. Furthermore, the results were compared to those of the structures with the WUF-B and RBS connections analyzed in the previous study. The structure with the WCPF connections showed 33% more improved structural robustness and 11% less sensitivity to progressive collapse when one column was removed. In a two-column removal scenario, only the structure with WCPF connections indicated to have proper progressive collapse resistance capacity. The WCPF connection was deemed more reliable than WUF-B and RBS ones.