| Shear wall with steel tube-confined high-strength concrete(STCHPC)is a new type of component applied to resist the lateral load.Results of previous research have proven its superior strength,stiffness,ductility and seismic performance.Recently experimental studies have conducted on the bending performance,the axial compression performance,the seismic performance,the shearing performance,the axial tension performance of STCHPC and its seismic performance in tube shape and shearing behavior under tensile force,based on which the design codes of STCHPC have been developed.However,steel tubes in STCHPC block the anchorage of the steel bar lay in the central position of the coupling beams.Two new types of STCHPC-coupling-beam joint are proposed as solutions to the problem.In this paper,12 specimens are subjected to cyclic and monotonic loading to verify the feasibility of the STCHPC-coupling-beam joint.The main research work and results are as follows:1)Two new types of STCHPC-coupling-beam joint,which are known as longitudinal ribs bending structure and longitudinal ribs with anchorage ends are proposed.Also,their feasibility,which is proven by the failure mode,are account for considering the superior bearing capacity,stiffness,deflection capacity and seismic capacity.2)12 specimens are tested under a suitable experimental setup.The main test variables are concrete strength grades,span-depth ratios and joint structures.The entire process of cracking,deflection,yielding and failure under cyclic and monotonic loading is studied.The results show that all specimens are subject to bending shear failure,and the anchorage of the longitudinal ribs of the coupling beams using the new joint structure proposed in this paper is reliable.3)The load-angle hysteresis curves,skeleton curves and monotonous load-angle curves of the specimens are analyzed.The crack load,yield load,peak load,stiffness characteristics,deformation ability,and seismic capacity under cyclic load and monotonous load are studied.The results show that the joints of STCHPC-coupling-beam joints have remarkable bearing capacity and seismic performance,which proves the feasibility under monotonous loading and cyclic loading.4)The phenomenon of the strains of the buckle longitudinal bars tend to lag behind those of the direct-anchoring longitudinal bars esists in both new types of joints.The strains of the buckle longitudinal bars only slightly lay behind when longitudinal ribs bending structure is applied.However,the buckle longitudinal bar strains lag behind substantially,and the lowcycle reciprocating loading and the low span-to-depth ratio can be the triggers of delaying the time at which the buckle longitudinal bars yield.It is worth emphasizing that the buckle longitudinal bars all yield before the specimens reach their limits.5)From the test results,it can be comfirmed that from the perspective of the anchorage,the longitudinal ribs bending structure is more reliable than longitudinal ribs with anchorage ends;but in terms of seismic performance,longitudinal ribs with anchorage ends excels the longitudinal ribs bending structure taking into consideration of its remarkable energy dissipation capability.6)Based on the experimental research,the nonlinear finite element software ABAQUS was used to establish the model of STCHPC-coupling-beam joints,outcome of which is compared with the experimental results.The results show that the finite element simulations are in good agreement with the experimental results.The research in this paper aims to propose two types of STCHPC-coupling-beam joints,demonstrating their feasibility,making up the gap in this area,and complete the theoretical system of STCHPC. |
