Seismic behaviour of high‐strength steel welded flange‐bolted web connections

Cyclic loading tests on two groups of welded flange‐bolted web connections employing 690 MPa high‐strength steels were conducted to quantify their plastic deformation and energy dissipation capacities under seismic loading conditions. The Q355 and Q690 beams in the two groups of specimens were designed with Class 1 and Class 3 cross‐sections, respectively; however, the Q690 columns in each group were designed nearly identical except for the thickness of their webs, which varied in order to identify the effect of shear panel strength on the connection seismic performance. Different beam‐to‐column flange welding types in each group were also considered. It was found that welding without backing bars should be used between Q690 beams and columns to accommodate some plastic rotation in the order of 0.01 rad in the beams, while a plastic shear distortion as high as 0.04 rad could be developed in Q690 web panels. This evidenced that those Q690 joint components could still sustain appreciable plastic deformations. In particular, Q690 web panels could be even qualified as high‐ductility class (DCH) in Eurocode 8.