Study On Seismic Performance Of Innovative Crimping PEC Column—Steel Beam Composite Frame With Welded T-stub Strengthened Connection

Partially encased composite column consist of thin-walled built-up H-shaped steel sections and concrete cast between the flanges with transverse links or tie-plate welded near the flange tips at intervals along the column height,combined with high strength and sound ductility of steel and excellent resist compression of concrete as its advantage,which called PEC Column.And the previous research achievements just studied on seismic performance of member,joint connection and inter-storey substructure in PEC composite frame structure.Hence,to acquire seismic performance of structural system composed of PEC column more comprehensive,innovative PEC column—steel beam composite frame with welded T-stub strengthened connection was taken as subject and took its consequences as theoretical criteria for practice engineering applications.The multi-storey of innovative PEC column—steel beam composite frame with welded T-stub strengthened connection was taken as prototype,a half-scale two-storey,one-bay specimen was designed and fabricated to be tested under lateral low-cycle reversed loading,in which the loading protocol is based on the principle of ‘weak earthquake frequently occurred,strong earthquake rarely occurred'.Meanwhile,the software called ABAQUS was adopted to build the finite element model,numerical simulation results were compared with the test to verify its rationality.Furthermore,vertical force was taken into account to analyze its effect.Based on the corresponding datum,the structure's every seismic performances and relevant stress characteristics as lateral resistant stiffness degradation,connection mechanical behavior,failure mode,energy dissipation,force transfer mechanism of inter-story,failure mode and additional vertical force parameter were studied.The analysis consequences demonstrated that this frame structure system owns high strength and large initial lateral stiffness.With the increasing loading of the frame model,the difference of lateral stiffness between the first-storey and the second-storey was reduced from high to low.Due to weld T-stub strengthened connection pre-tension penetrating bolts were fabricated,the design objective of force-transfer mode of concrete equivalent strut in panel zone,self-centering function of connection and plastic hinge forming location of beam end apart from the panel zone were all achieved to meet the seismic code of ‘Strong joint' of design requirement.The first-storey of PEC column sustained 60 percent of tangential force at compression side and the second-storey of PEC columns sustained lateral shear evenly,which demonstrated that the deformation of inter-storey was induced by shearing.The energy dissipation capacity of frame model was provided by yielding of entire steel beam section near the end of T-stub web and steel yielding and concrete crushing at bottom of PEC column that first-storey was in accordance with second-storey.The failure mode of the frame model was given rise to the plastic hinge of bottom of the PEC columns and the beam near end of T-stub web,inter-storey drift angles and joint connections angles of specimen were both exceeded the value limitation of 1/30 at maximum consideration earthquake level,accordingly,this frame model possesses excellent seismic performance.The vertical force parameter enhanced the initial lateral stiffness of the specimen,but its collapse moment accelerated the yield damage process of specimen,which reduced its ultimate loading-capacity.