Research On Mechanical Properties Of Cross-shaped Superposed Shear Wall-floor Slab Joint

The superposed shear wall structure meets the concept of building industrialization in China.Industrial production was realized from component design,production to field assembly.Compared with the traditional on-site pouring construction structure,the superposed shear wall structure has the advantages of easy construction,resource economizing and friendly to the environment,which accords with the sustainable development thought and pushes our country green building development.Nowadays,the superposed shear wall structure is applied widely in public and industrial buildings,and its weak position is at the joint.For further work over the stress performance of the superposed shear wall joint,based on the static test of the cross-shaped superposed shear wall,the mechanical properties of the superposed shear wall-floor slab joint are studied in this paper.The failure mode,crack development,load-displacement curve,load-strain curve and other mechanical performance indexes were numerically simulated by the finite element analysis software ABAQUS to explore the influence of the thickness of the superposed floor slab,the anchorage form of the longitudinal reinforcement of the floor slab,and the concrete strength grade on the mechanical properties of the joint.The main research work and results are as follows :（1）The cross-shaped superposed shear wall-floor slab joint specimen is designed and manufactured,and the static load is applied at the end of the floor slab.Cracks first appeared at the wall-floor slab interface of the superposed shear wall-floor slab joint specimen,and then cracks gradually generated and spread in the upper tensile floor slab of the joint.Finally,the tensile failure of the upper floor slab of the joint and the crushing failure of the lower concrete of the joint ended,and no damage occurred at the joint.The failure mode is typical flexural failure,and the bearing capacity and deformation capacity of the specimen are better.It shows that the joint structure designed by the experiment is reasonable and meets the engineering requirements of ’ strong joints and weak components ’.（2）Through the research on the crack development,failure mode,load-displacement curve and load-strain curve of the cross-shaped superposed shear wall-floor slab joint specimens,it is found that the uniform loading method is more beneficial to improve the mechanical properties of the cross-shaped superposed shear wall-floor slab joint.After reached peak value,the lording capacity of the specimen will be reduced to some extent.The strain trend of precast layer concrete and cast-in-place layer concrete is similar,the strain at the joint is small and the integrity is good.（3）The finite element software was used to model the cross-shaped superposed shear wall,and the results were compared with the static load test results.It was found that the finite element simulation results were reliable.The parameters such as the constitutive selection,the interaction setting of the superposed surface,and the meshing could better simulate the bending performance of the specimen.The numerical error of each feature point was within 12 %.The simulation results are matches well with the load-displacement curves of the experimentation results.which could provide the basis for the subsequent test parameter analysis.（4）Through the finite element numerical analysis,it can be found that increasing the thickness of the superposed floor slab by 10 mm and 20 mm can improve the bearing capacity of the cross-shaped superposed shear wall-floor slab joint,and the effect of increasing the thickness of the prefabricated slab alone is more obvious under the same conditions.There is no obvious difference between the direct penetration anchorage and the bending anchorage of the longitudinal reinforcement of the floor slab on the mechanical performance of the specimen,but the effect of the bending anchorage is slightly better,which can meet the needs of practical engineering.Increasing the strength grade of concrete can improve the mechanical properties of specimens,but with the increase of concrete strength grade,the improvement effect is getting smaller and smaller.