Experimental Investigation On Shear Behavior Of RC Short Columns Confined With Superelastic Shape Memory Alloy Wires

Short column as an important one of the vertical bearing component of concrete structure,due to its high lateral stiffness and poor deformation capacity,it is often prone to occur brittle shear failure under the action of earthquake. Prestressed SMA strengthening technology is a new building structure strengthening method,which based on the new type of intelligent material-shape memory alloys(Memory Alloys Shape, that is, SMA).It uses two special properties of shape memory alloy, super elasticity and shape memory effect,which can provide the short column reinforcement good lateral confinement and strong restoring force. It is a new try of reinforcement technology, which combines the existing mainstream of the technology process with shape memory alloy properly.There should be a good application prospect in the field of reinforcement of existing buildings.In this paper, we give priority to the study of the mechanical properties of 1.2mmSMA wire.It can Provide a reliable theoretical basis for the design of the subsequent short column reinforcement test plan.1 RC short columns strengthened by contrast and 8 SMA wire were then carried out in the low cycle reciprocating test.Experimental study on RC short column with the constraint of super elastic shape memory alloy wire,from the perspective of different axial compression ratio,SMA wire material prestress level, and allocation rate condition experiment on all components of the upper end of applying low cycle reciprocating horizontal load. The stress of the simulation under the action of earthquake.The cracking, yielding and ultimate load of all specimens were measured. Lateral displacement of the upper end of the column and the main parameters of the strain of the column.The load displacement hysteresis curve of the test piece is completed by the experimental data and test date. Analysis of skeleton curve, bearing capacity and ductility. And analysis of stiffness degradation curve and energy dissipation capacity. Studied the law of the axial compression ratio, strain value and amount of reinforcement on the damage form of RC short column, shear capacity,deformation behavior and energy dissipation mechanism.Research results show that axial compression ratio,SMA wire material prestress level and configuration rate have a more obvious impact on damage morphology of RC circular short columns in shear capacity, deformation behavior and energy dissipation mechanism.In order to have a certain ductile bending shear failure or bending failure.The failure modes of RC short columns after constraint are destroyed by the shear failure of the Contrast column.Under the condition of low and medium axial compression ratio.The seismic performance of the specimens is increased with the increase of axial compression ratio.However, under the condition of high axial compression ratio.In addition to the shear bearing capacity of the test specimens, the effect is not very large. Other seismic performance has a certain degree of attenuation the constraint of the prestressed specimen will be more than that of the non pre stressed specimens,better to participate in the force of the RC cylinder,shear stress on the specimen.The core concrete of the restrained specimen is better to improve the seismic performance of specimens with the improvement of the silk material allocation rate,the shear capacity, ductility and energy dissipation capacity of the restrained specimens show a nonlinear trend.