Seismic Performance Research On Self-centering Steel Connections With Post-tensioned High-strength Steel Strands And T-stubs

The steel self-centering moment resisting frames achieve the performance of selfcentering and energy dissipation by running Post-tensioned(PT)high-strength Steel Strands along the beam and setting energy-dissipation elements respectively.Traditional steel selfcentering moment resisting frames arrange single method to dissipate energy such as setting angles and steel shear wall.The research use T-stubs and force of friction to dissipate energy which can reinforce the capacity of energy-dissipation and safety.The steel self-centering moment resisting frames with T-stubs are in need of forming up reliable connections between columns and beams when applied to steel self-centering structure.The self-centering steel beam-column joint with post-tensioned high-strength steel strands and T-stubs is the key part for the structural system when required of transmitting force reliably.And its seismic performance has significant influence on the structural system.A new selfcentering steel beam-column joint with post-tensioned high-strength steel strands and T-stubs based on a real civil engineering is proposed in this paper from the perspective of reasonable force-transmitting,simple configuration and easy construction.With the purpose of investigating the seismic performance of the kind of self-centering steel beam-column joint with post-tensioned high-strength steel strands and T-stub,the five fullscale self-centering steel beam-column joints with post-tensioned high-strength steel strands and T-stubs specimens which include different prestressing force and the thickness of T-stubs plate were designed so as to conduct quasi-static cyclic tests.The five specimens’ failure process and working status of the key part were analyzed.Seismic behaviors such as bearing capacity,ductility coefficient,stiffness degradation and dissipative coefficient could be derived from the hysteretic curves and skeleton curves.The experimental results indicate that five connections failure are plastic hinge at the end of the frange and web of T-stubs.The beams and columns are not found to have obvious deformation,which is good to satisfy performancebased design.The double-flag hysteretic curves indicate excellent self-centering performance.Five different configurations of the self-centering steel beam-column joint with posttensioned high-strength steel strands and T-shaped steel specimens were simulated by the finite element analysis software ANSYS.Failure characteristics,hysteretic curves,skeleton curves,bearing capacity,ductility coefficient,stiffness degradation,dissipative coefficient and strain distribution on key positions of the connections were concluded from finite element modeling.Finite element simulating results were well in accord with the experimental results.The accuracy of finite element models was therefore verified.Parametric analysis for the self-centering steel beam-column joint with post-tensioned high-strength steel strands and T-stubs was conducted through finite element method in order to reveal the influence of the prestressing force and the thickness of T-stubs,the friction coefficient.A few guidelines are suggested for the design and application of the standard selfcentering steel beam-column joint with post-tensioned high-strength steel strands and T-stubs.A design method toward the self-centering steel beam-column joint with post-tensioned highstrength steel strands and T-stubs are proposed on the basis of relevant design code,which will provide important evidence for the application of the self-centering steel beam-column frames with post-tensioned high-strength steel strands and T-stubs.The M-θ curve of new type joint was drawn on the base of the ANSYS results and experimental data,and the initial rotational stiffness was calculated which showed that the new type joint belongs to semi-rigid connections;This paper fitting out a suitable moment-rotation relation model,and through comparing with the ANSYS results and experimental data,showed that the proposed bending moment-corner relation model has good accuracy and can be used for reference in the new type connection design and practical application.