Seismic behaviour of novel self-tightening one-side bolted joints of prefabricated steel structures

In response to the requirements of building industrialization and sustainable development, prefabricated steel structures are vigorously promoted in recent years. The joint is an important part of prefabricated steel structures. The response of the structures under earthquake is directly determined by the seismic behaviour of the joints. Square steel tube columns and H-section steel beams are widely used in prefabricated steel structures due to the superior mechanical properties. Nevertheless, the bolted joints need to be operated on both sides. To solve this problem, a novel self-tightening one-side bolt (STOSB) was proposed based on the self-tightening high strength one-side bolt (SHSOB) developed by our research group. The behaviour and failure mechanism of the prefabricated steel structure joints based on the STOSBs under the low cyclic loading were revealed. Based on the existing experimental research, the finite element software ABAQUS was used to establish the refined numerical models of three fabricated steel joints. The numerical simulation analysis was carried out to verify the practicability of the STOSBs in practical engineering. The equivalent viscous damping ratio ζ - inter-story drift angle θ curve, hysteretic curve and skeleton curve of each specimen were obtained. On this basis, a parametric analysis was carried out to explore the effects of the column flange thickness, column diaphragm plates, endplate thickness, endplate stiffeners and other factors on the seismic behaviour of this novel joint. Subsequently, according to the moment - rotation hysteretic curves determined by the finite element analysis, a restoring force model of this novel joint under the low cyclic loading was established. The results show that the STOSBs can be used in practical engineering. The failure mode of each specimen is that a plastic hinge appears in the steel beam above the stiffeners. The endplate is always close to the column flange during the test. The seismic behaviour of the joint is significantly influenced by the endplate stiffness and column flange thickness. The bearing capacity, energy dissipation and rotational stiffness of the joint are enhanced with the endplate stiffness and column flange thickness increasing. Setting diaphragm plates in the steel column opposite to the upper and lower flanges of the steel beam can achieve similar results. When the stiffness of the endplate or column flange is weak, the moment - rotation hysteretic curve is full and the joint is a semi-rigid joint. When the stiffness of the endplate and column flange is strong, the moment - rotation hysteretic curve is in an elastic range and the joint is a rigid joint. The hysteretic behaviour of such joints under the low cyclic loading can be well simulated by the restoring force model established herein.