Research On Interstory Collapse Mechanism Of Crimping PEC Column –steel Beam Composite Frame With Welded Split-tee Connection

Partially encased concrete composite column is a new type composite column, it fully utilize material property of steel tension and concrete compression by interacting effect,correpondingly it possesses has higher load-carrying capacity, lateral stiffness and sound energy dissipation capacity.The traditional PEC column is made of hot rolled thin-walled built-up section with transverse links leads to some shortcomings of biaxial stiffness unequality and construction difficulity, hence the research group come up with a new type PEC column by flange crimping and tensioning plate installation. Up to date, most of researches were concentrated on PEC column and joint connection, but research on the structure system is deficient, so it is necessary to investigate the seismic performance of PEC column-steel beam composite frame structural system.The inter-story substructure of innovative crimping PEC column — steel beam composite frame with welded split-tee connection was taken as studying 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 velidate the rationality and feasibility of the finite element model, and further analyze the influence of axial force 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 owns high strength, large lateral stiffness and soundly energy-dissipation capacity; the inter-story shear was sustained by PEC columns evenly and the drift deformation pattern is shear-type; all joints exhibited various degrees of self-centering function attribute to pre-tension penetrating bolts; Split-tee enforces the joint and the plastic hinge location of beam end is away from joint zone to near end of Split-tee plate; the collapse mechanism formed primarily induced by plastic hinge in reduced cross-section of steel beam, interstory drift and connection rotation both surpassed the limit(1/20) of maximum considered earthquake for frame structure, correspondingly the specimen owns sound collapse resistance. The study presents theoretical basis for further research and engineering practice of the structure composited of PEC columns.