Study on the seismic behavior of connection via welding strengthening under load

Abstract

This study proposed a reinforced connection with an outer annular stiffener for square hollow section (SHS) columns and H–beams. Low-cyclic-load tests were designed for three strengthening specimens and one common specimen. The verified finite element model was used to study the impact of the welding thermal effect, axial compression ratio, and vertical stiffener size on the seismic performance of joints. The results showed that joints reinforced with an outer annular stiffener for SHS columns and H–beams can effectively transfer loads. Compared to common joints, their moment resistance increased by 75%–113%, the energy dissipation coefficient increased by 5.5%–20.4%, and the moment resistance of the strengthened joints was significantly different in the positive and negative directions. In the process of welding strengthening, the influence of the welding thermal effect can be ignored. When the axial compression ratio was greater than 0.7, the moment resistance decreased by more than 14%. The strengthening was optimal when the vertical stiffener thickness was not less than 40% of the column wall thickness or 6 mm, the enlarged flange connection plate was completely wrapped, and the lap length was within 10–20 mm of the upper and lower steel angles