Seismic performance of welded-bolted joint between double channel beam and CFST column

Abstract

A novel welded-bolted beam-to-column joint, connecting double channel beams to concrete-filled steel tubular (CFST) columns, is proposed for a prefabricated steel structure that only need bolted assembly on site in construction. To investigate the seismic performance of the proposed joint, eight full-scale specimens were designed and tested under cyclic loads, and the joint moment resistance, stiffness, hysteretic behaviors, slipping behaviors, ductility, and and energy dissipation capacity were analyzed. Finite element models were built and validated by the test results, and the bolt tensions, the friction between slip surfaces and the bearing force on the bolt hole were further investigated by the finite element analysis. According to the results, the slip load of the bolted channel becomes larger and the hysteretic curve becomes plumper with the increase of the number or the diameter of the bolts. The increased bolt hole size showed no significant effect on the plumpness of the hysteretic curve but would increase the slip distance, thus increasing the energy dissipation capacity. Compared with the welded joints from the FEA results, the welded-bolted joints could develop larger rotation capacity, energy dissipation capacity and ultimate moment. Based on the investigations, the proposed novel joints could be designed as rigid joints. Based on the investigation, formulas of the yield and ultimate moment resistance of the welded-bolted joints were proposed and validated by the experimental results.