Experimental and numerical study on high-strength steel flange-welded web-bolted connections under fire conditions

Experimental and numerical study on high-strength steel (HSS) flange-welded web-bolted connections at ambient temperature and under fire conditions are conducted in this study to reveal their fire behaviors. Eurocode 3 Part 1-8, AISC360-16, and GB50017-2017 are compared with the experimental results to verify the applicability of the current specifications on HSS connections. Furthermore, the finite element model validated by experimental results can reasonably simulate the behaviors of HSS flange-welded web-bolted connections under fire conditions and at ambient temperature. At ambient temperature, the provision of Eurocode 3 Part 1-8 on the flexural capacity of the connections seems rather conservative, while those of GB50017-2017 and AISC360-16 are unsafe. Improving the weld quality is significant to avoid weld failure of HSS flange-welded web-bolted connections. In addition, appropriately matching the steel grade and thicknesses of the web, as well as the flange of beam-column components should be considered. The elastic design method and the plastic hinge relocation mechanism should be discussed sufficiently in future optimization design. This study can be employed for performing performance-based optimization analysis and fire-resistance design of HSS flange welded web-bolted connections.