Experimental Research On Special-shaped Column Exterior Joints Reinforced By Polypropylene Fiber Concrete

The destruction of fra me structure with special-shaped columns is concentrated in the joints, the column foots and other weak points, thus polypropylene fiber is used to reinf orce local of joints. In th is paper , f iber re inforced concre te m echanical properties a nd f iber reinf orced exterior joints tests with theoretica l analysis a re conducted, to study the fiber enhancem ent in the seism ic perform ance of special-shaped column exterior joints. Specific work is as follows:In this paper, mechanical performance of polypropylene fiber reinforced concrete test is conducted, to study the mechanical properties and energy dissipation capacity for concrete reinforced by polypropylene fiber . After that, the author has four special-shaped column exterior joint specimens (1/2 sc ale) in the cyc lic loading tes t under study. Four specimens are identical in size and for m of reinforcement, through pouring polypropylene fiber concrete in dif ferent parts of the exterior joints, the seismic performance of exterior joints, including strength, ductility, energy dissipation, stiffness, residual deformation, cumulative damage, and strain variation of the stirrups and longitudinal reinforcement are researched.Through the mechanical performance test and stress-strain curves test, the author conclude that: comparing with plain concrete test block, the adding of polypropylene fiber has no significant incr easing on concrete com pressive strength, but the late concrete strength, toughness, and ener gy dissipation capacity im prove significantly. The author proposes co nstitutive models for fiber reinforced concrete, which are in good agreement with the experim ental curve. Through the low cycle test on exterior joints, it is showed that: co mparing with ordinary conc rete special-shaped colum n exterior joint, the deform ation, energy dissipation capacity of polypropylene fiber reinforced concrete special-shaped column connections are strengthened, the stiffness degradation is slowed, the cum ulative damage is reduced, and the strain of steel i s released.In th is pa per, th e au thor b riefly discuss es the sh ear m echanism of the beam-column joints with special-shaped column according to the shear mechanism of the rectangular column joints, and analyzes the influence of the fl ange, stirrups, fiber to the node shear bearing, which verifies th at: shaping polypropylene fiber reinforced concrete in joints'weak position combination is feasible.