Mechanical Properties Of Steel-concrete-steel Composite Shear Wall With Horizontal Joint Connected By Bolts

The traditional reinforced concrete shear wall has a large cross section and a large weigh,which reduces the usable space and increases the construction cost.The use of steel-concrete composite shear wall can reduce the size and weight of the structure while ensuring structural safety.In the traditional construction method,the steel-concrete composite shear wall has a large amount of welding operating on the construction site,and the quality is difficult to guarantee.In order to overcome these shortcomings,it is necessary to improve production efficiency,and make the steel-concrete composite shear wall can be widely used in high-rise and super high-rise buildings.An innovative structural form was proposed in this paper,which is steel-concrete-steel composite shear wall with horizontal joint connected by bolts.In this paper the mechanical properties of the innovative composite shear wall were studied by a combination of experiment,finite element simulation and theoretical analysis.The main research contents and results are as follows.(1)An innovative structural form was proposed,which is steel-concrete-steel composite shear wall with horizontal joint connected by bolts.It has the following main advantages:(1)A large amount of on-site welding operating of double-layer steel plate can be avoided.(2)The steel box of shear wall could be produced and installed with modularization way.(3)The steel structure part is used as the formwork of the concrete.No formwork is needed at the construction site,which is consistent with the characteristics of prefabricated structure.(4)This structure is economical.(2)Quasi-static tests were performed on 7 specimens of the innovative composite shear wall to study the effects of the construction of vertical seams and different joint types on their seismic behavior.The results show that:(1)The innovative composite shear wall has excellent seismic performance such as high ductility,stable bearing capacity and stiffness,and good energy dissipation capacity.Its main mechanical properties exceed the requirements of the current codes.(2)Compared to the specimens with vertical welding seam,the bearing capacity of the specimens with vertical divider seam is reduced by about 25%,but the ductility performance is improved.The bearing capacity of the specimens with horizontal joint connected by bolts and the specimens with horizontal joint connected by welding are similar.(3)The specimens with linear type seam connected by bolts and the specimens with sawtooth type seam connected by bolts has basically the same excellent mechanical properties.The mechanical properties of the specimens with groove type seam connected by bolts are relatively poor.Considering the complexity of the production,it is recommended that the shear wall adopt the linear type seam connected by bolts.(3)Quasi-static tests were performed on 9 specimens of the innovative composite shear wall with linear type seam connected by bolts.The parameters of the specimens included the axial compression ratio,the connection method of the upper and lower layers,the thickness of the steel pipe of the edge members,and restraining bar.The results show that:(1)The deformation capacity and bearing capacity of specimens decreases as the axial compression ration increases,and it increases as the thickness of the steel pipe increases.The deformation capacity and bearing capacity of specimens can be improved by the connection method of the upper layer bolt connection and the lower layer welding.Restraining bar has effect on delaying local buckling of steel plate and constraining infill concrete.(2)Under horizontal load,the edge members and middle wall are working relatively independently.The longitudinal strain distribution of the middle wall basically conforms the plane section assumption.(4)The finite element model of the innovative steel-concrete-steel composite shear wall was established.The stress mechanism of the innovative composite shear wall under horizontal load and the effect of different parameters on its performance were analyzed.The results show that:(1)The mechanical properties of the innovative steel-concrete-steel composite shear wall are simulated accurately by the finite element model.The simulation results agree well with the test results.(2)The connecting bolts bear the bending moment of specimens,and concrete in shear-compression zone transfer the horizontal shear of specimens.The edge members and middle wall of specimens with vertical seams bear load independently.The edge members and middle wall of specimens with vertical welding seams bear load together.The bearing capacity of the specimens increases as the strength of concrete and steel plate increases,and it decreases as the shear span ratio increases.The bearing capacity of specimens increases when the axial compression ratio increases from 0.2 to 0.6,and it decreases when the axial compression ratio exceeds 0.6.(5)Based on the results of test and finite element research,the stress characteristics and stress mechanism of the innovative composite shear wall during failure were analyzed,and the cross-sectional stress distribution of the innovative composite shear wall was summarized.According to the equilibrium condition,the calculation formula of normal section bearing capacity was proposed for the innovative composite shear wall.By modifying the current calculation formula of shear capacity,the calculation formula of shear capacity was proposed for the innovative composite shear wall.It can be seen from the comparison that the calculation results of bearing capacity agree well with the test results.The proposed calculation method of bearing capacity could be used for the actual engineering design.