Study On The Load Bearing Capacity Of Prefabricate Steel Truss And Concrete Composite Shear Wall

Steel truss-concrete composite shear wall(also referred to as "truss shear wall")is formed by placing the steel truss instead of the steel reinforcement in the reinforced concrete shear wall.This kind of shear wall can not only make better use of the advantages of steel and concrete,but also overcome the shortcomings of the steel structure that is not resistant to corrosion and fire,and at the same time the ductility of the shear wall is good.The truss shear wall can be assembled and connected through the truss,which can reduce the wet work on site,accelerate the construction progress,and be beneficial to the assembly construction.At present,there are few researches on the performance of truss shear wall structure,which restricts the development of this new type of structure.In this thesis,the mechanical behavior of truss shear wall is studied,the seismic behavior of truss shear wall under the cyclic load is tested,the finite element model is established and the parametric analysis is carried out.Based on the test and analysis results,the calculation formula of the bearing capacity of truss shear wall is given.At the same time,in order to study the vertical connection performance of truss shear wall,the shear wall with joints is modeled and analyzed by finite element method.The research contents are as follows:(1)A total of four truss shear wall specimens with a shear-span ratio of 1.65 were tested with considering the influence of different axial compression ratios and different forms of shear bonds on the bearing capacity,stiffness,deformation ability,hysteresis curves and failure modes of the specimens.The results showed that the axial compression ratio had an effect on the failure modes of the truss shear wall,and the increase of the axial compression ratio led to that the failure modes of the specimens changed from the shear slip along the inclined crack to the shear failure after the steel section buckling.Strong shear connector could effectively alleviate the pinch phenomenon in truss shear wall and improve the energy dissipation capacity of the shear wall,but it had little effect on improving the bearing capacity of shear wall.(2)The finite element software ABAQUS was used to conduct numerical simulation of test specimens,and comparative analysis between tests and numerical analysis was conducted from four aspects: hysteretic curves,skeleton curves,failure modes and key parameters.The influence of axial compression ratio and steel ratio on the performance of shear wall was investigated by parametric analysis within the model.The results showed that the finite element model could simulate the failure process and bearing capacity of truss shear wall well.The proportion of the chord of steel truss had a great influence on the shear capacity of the shear wall,while the proportion of the diagonal braces had a little influence on the shear capacity of the shear wall.Under the same steel ratio,the shear capacity of shear wall tended to decrease with the increase of axial compression ratio.The higher the steel ratio of chord was,the greater the decrease will be with the increase of axial compression ratio.(3)The finite element software ABAQUS was used to model the vertical connection of steel truss-concrete composite shear wall.The mechanical performance of shear walls with joints under monotonic load was analyzed,and the failure modes of shear walls under the yield load,the peak load and the ultimate load were analyzed.Finally,the failure modes of shear walls with and without joints under the monotonic load were compared and analyzed.It could be seen from the comparison that the bearing capacity of shear walls without joints were lower than that with joints,but the ductility did not change.(4)The contribution of steel truss to the shear capacity of shear wall was analyzed.Based on the existing formula in the Code for Design of Composite Structures JGJ138-2016,the formula of shear capacity suitable for single-diagonal truss shear walls was given.The inter-story drifts of truss shear walls under different performance levels were calculated and analyzed.The results showed that: the crack displacement and the ultimate displacement of the specimens could meet the requirements of the specification.