Study On Seismic Behavior Of Double-Channel Built-Up Member With RC Slabs

The diagonal web of composite staggered truss structure system was buckled or fractured under earthquake.The failure of the composite staggered truss structure system was brittle.In order to improve the seismic performance of the structure,the concept of ductile staggered truss steel frame structure was proposed.In special staggered truss frame structures,the vierendeel panel of the truss near the midspan was designed a ductile section,which enter inelastic and the rest members of the structure remains elastic during a rare event.In this paper,the chords of a special staggered truss steel frame structure use double-channel built-up member and consider the effect of slabs.The seismic behaviors of the double-channel built-up member with RC slabs were analyzed in detail by means of specimen tests,numerical models and restoring force model.The main work and achievements are summarized as follows:(1)Four double-channel built-up members with RC slabs were tested under axial pressure and cyclic bending.The influence of stich plate spacing,stiffener in plastic hinge area and web depth-thickness ratio on failure modes and seismic performance were mainly studied.The test results showed that reducing the stich plate spacing can ensure both channel of the member work together,reducing the web depth-thickness ratio can restrain the deformation of the channel steel flange.Both can delay the speed of the carrying capacity decreasing,and improve the ductility and energy dissipation capacity of the members.Stiffener in plastic hinge area can restrain the bucking deformation of the channel steel in the early stage of loading and improve the carrying capacity and stiffness of the member.However,there was obvious tension fracture inthe channel steel near the gusset plate at the end of loading,which makes the bearing capacity and energy dissipation capacity of the members decrease rapidly.(2)Finite element models of double-channel built-up members with RC slabs were established by ABAQUS.The accuracy and rationality of the FE model was proved by the comparison between the finite element simulation and the test results under cyclic loading.(3)The influence of reinforced concrete slab on seismic performance of members was studied by the FE model,meanwhile the effects of different parameters,such as coefficient of axial force,stich plate spacing,web depth-thickness ratio,RC slabs height and reinforcement ratio,were analyzed based on the FE model.(4)Based on the experiment,the restoring force model of the double-channel built-up member with RC slabs was established.The model had a favorable accuracy with the experimental results,which can well reflect the bearing capacity and stiffness degradation of members under cyclic loading and provide references for elastic-plastic analysis of members.