Seismic performance of beam-column connections with welded upper flange and bolted lower flange

Abstract

In a prefabricated steel structure, excellent seismic performance of the beam-column joint provides a guarantee for the overall stability of the structure. A new beam-column joint differs from the the traditional beam-column that uses a butt weld instead of bolts to connect the steel beam, known as the welded upper flange and bolted lower flange connection (WUFBLC) is proposed in this article. To investigate the seismic performance of the WUFBLC, four specimens were tested under cyclic loading. The primary test parameters are the cross-sectional area and number of bolts in the lower flange splice plates. Four test specimens presented two distinct failure modes: buckling deformation on the splice plates and tearing damage of the welds at the beam-column end. Subsequently, hysteretic curves, skeleton curves, ductility coefficient, and strain distribution were obtained. The experimental results showed that the WUFBLC uses the friction slip between the splice plates and the frame beam to dissipate energy. All specimens exhibited enhanced ductility and rotation angles. Changing the thickness of the lower flange splice plates is more significant for the bending capacity more than does changing the width. Finite element analysis was conducted to clarify the seismic behaivor of beam-column connections with welded upper flange and bolted lower flange. The results of experiment were confirmed by finite element analysis, thus the finite element model can be applied to measure the seismic performance of the connections with reliable data.