Seismic behavior of bolted truss-to-column joint with oversized or slotted bolt hole

Abstract

Bolted connections are preferred in prefabricated steel structures because of the convenience for construction and quality control. A prefabricated steel structural system with truss beams and bolted joints were proposed, and enlarged bolt holes were adopted in the joints for easier assembly and better energy dissipations. A series of 6 truss-to-column joint specimens, with oversized or slotted bolt holes, were tested under cyclic loads. The resistance, the hysteresis behaviour, the ductility, the energy dissipation capacity, and the slipping behaviour of the tested joints were analysed, and the influences of the bolt hole dimensions and shapes were evaluated. Finite element models were established and validated for further investigation of the joint performances. According to the results, the enlarged bolt holes would slightly decrease the slipping resistance, but would significantly improve the joint ductility and energy dissipation capacity. The slippages in the joints with oversized or slotted bolt holes could make 38%∼59% of the contributions to the energy dissipation capacity, proving that the slippages could be utilized in seismic design. Based on the investigations, the diameters of the oversized bolt holes are recommended to be 4 mm larger than the nominal bolt diameter, and a 0.3 mm-thick copper plate is recommended to be adopted between the connected plates to obtain stable slip behaviours. Simplified calculation methods for the slipping resistance and the yield resistance of the investigated joints were proposed and evaluated to have acceptable accuracy for resistance prediction and design.