Study On Interstory Collapse-prevention Mechanism Of PEC Column Fabricated With Thin-walled Built-up Section-Reduced-Section Steel Beam Composite Frame Substructure

Partially encased composite(PEC) column generally consists of H-shape steel section or steel plate composited section with transverse links welded and concrete casted between opposing flanges.Up to date, the current researches of PEC column was focus on the member and beam-column joint,and the research on mechanical performance of PEC column—steel beam composite frame structural system is vacancy, consequently studying its seismic performance will be of great theoretical significance and engineering application value.The inter-story substructure of steel plate composited section PEC column—steel beam(reduced section) composite frame with end-plate connection was selected as subject, the 1:2 scale test specimen was designed and fabricated based on the loading capacity of the instuctions in lab. The test was conducted under lateral low-cycle reversed loading, the hysteretic curves and failure mode were derived. Meanwhile the software ABAQUS was adopted to simulate the test specimen its mechanical performance to verify the rationality and feasibility of the finite element model, and further analyze the influences of axial force and stiffness matching of beam-column on the behavior of specimen. Based on the data, the specimen’s performances were analyzed, including the loading-carrying capacity, lateral stiffness, connection mechanical performance,capacity of energy dissipation, drift deformation pattern, force-transfer of joint and failure mechanism.The results indicated that the specimen processed high strength and initial lateral-resisting stiffness; lateral force was sustained by PEC columns evenly and the drift deformation pattern is shear-type; all joints captured partial self-centering function resulted from pre-tension penetrating bolts; reduced-section of beam make plastic hinge leave from the join zone to provide soundly rotational and energy-dissipation capacity; the collapse mechanism formed primarily induced by plastic hinge in reduced cross-section of steel beam, and interstory drift and connection rotation both surpassed the interstory drift limit(1/30) of maximum considered earthquake for frame structure, correspondingly the specimen owns soundly ductility and collapse prevention capacity. Research results will further enrich the research achievements of PEC column, also provides the theory support for later research and engineering application.