Hysteretic Performance of Circular Concrete-Filled Steel Tubular T-joints with Spherical-Cap Gap
In order to study the influential mechanism of spherical-cap gap on the seismic performance of circular concrete-filled steel tubular(CFST)T-joints,a serial of hysteretic tests including 18 circular CFST T-joints under the combined action of constant axial tension on the CFST chord and axial cyclic loading on the brace were carried out with gap ratio,diameter ratio of brace to chord and diameter to thickness ratio of chord as the main test parameters.The effects of spherical-cap gap on the failure mode,hysteretic curve,skeleton curve,ultimate strength,stiffness and energy dissipation of circular CFST T-joints were experimentally investigated.The finite element analysis model was established,where the influence of spherical-cap gap on the contact stress between steel tube and concrete of the chord was analyzed,and a series of parametric studies were conducted to investigate the effects of gap ratio,diameter ratio of brace to chord,the diameter to thickness ratio of chord,concrete strength,steel strength and axial tension ratio on the ultimate tensile strength of circular CFST T-joints.The results show that the existence of gap tended to change the failure mode of T-joints,decrease the ultimate strength,stiffness and energy dissipation capacity of specimens to some degrees,weaken the interaction between steel tube and concrete of the chord,and affect the force transferring mechanism of the joint.Finally,a simplified formula to predict the ultimate tensile strength of circular CFST T-joints considering the effect of spherical-cap gap was proposed.
concrete-filled steel tubular T-jointtension-bendingcyclic testspherical-cap gapfinite element analysis
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