Progressive collapse behaviour of end-plate beam-to-column connections with austenitic stainless steel bolts

This paper presents an integrated experimental and numerical study into the application of austenitic stainless steel bolts to enhance the progressive collapse performance of end-plate beam-to-column connections. Four substructure specimens, designed with flush and extended end-plate connections, were tested to simulate a middle-column-removal scenario in a steel frame structure. To isolate the effect of using austenitic stainless steel bolts, two comparative tests were performed for each connection type: one featuring conventional carbon steel (G8.8) bolts and the other featuring austenitic stainless steel (A4–80) bolts. The test results clearly demonstrated that the use of A4–80 bolts instead of G8.8 bolts greatly enhanced the ultimate resistance of the connections. The enhancement in dynamic load resistance (a key performance index of progressive collapse resistance) was 94% and 56% for the flush and extended end-plate connections, respectively. Subsequently, an advanced finite element (FE) model capable of simulating fracture in steel components was developed to further investigate the behaviour of the connections under column removal. The validated FE model was employed to perform a comprehensive parametric study to examine the effects of different design parameters on the connection behaviour. It was found that the end-plate thickness and the number of bolt rows are the most critical parameters influencing the behaviour of the connections under column removal. Finally, a limit value for end-plate thickness was proposed to efficiently utilise austenitic stainless steel bolts for enhanced progressive collapse resistance.