Structural performance of steel-truss-reinforced composite joints under cyclic loading

Abstract

The steel-truss-reinforced composite beam is a type of steel-reinforced concrete structure, in which the concrete beam is reinforced by steel trusses. Unlike traditional reinforced concrete structures, the steel truss works as the main skeleton and takes the main responsibility for the whole structural strength. In order to fulfil energy dissipation requirements, diagonal angle steel crosses are placed at the end of the steel truss. Specimens are designed based on different key parameters, including axial compression ratio and dimensions of chord, web and angle steels. Low-cyclic reversed loading tests are carried out on eight interior joint specimens to simulate realistic reversed loading conditions under earthquake. Load–deflection hysteresis loops and skeleton curves of joint specimens are obtained. Ductility, hysteresis behaviour and seismic-resistant performance are evaluated. Equivalent viscous-damping coefficients and energy dissipation indicators are calculated. The influences of axial compression ratio and steel ratio on the seismic performances are analysed. It is found that a large steel ratio will generally increase the bearing capacity. However, a relatively high axial compression ratio will benefit the bearing capacity of joints, but has adverse effects on hysteresis behaviours. Further, some conclusions are drawn on the overall seismic performances of this type of joint.