Research On Seismic Behavior Of Directly Embedded Joint Of Hybrid Coupled Wall

The steel beam is used instead of the original reinforced concrete beam to form hybrid coupled wall system.It combines the advantages of strong deformation ability of steel beam and large lateral stiffness of concrete shear wall,and is more suitable for high seismic fortification intensity area.The mechanical properties of the joint between steel beam and shear wall are very important to ensure the seismic performance of the hybrid coupled wall system.At present,there are few research results on directly embedded joint in China,and there are great differences in the research results abroad and the node structure is more complex.By simplifying the construction measures of the joint and combining with the relevant specifications of our country,this paper puts forward the suggestion formula for the design of embedded joint of hybrid coupled wall,which can provide data support for the design of directly embedded joint in the hybrid joint wall and provide the basis for the design and application of the hybrid joint wall system.Therefore,the seismic performance of directly embedded joint needs to be further studied.In order to study the seismic performance of the joint,the finite element simulation of the hysteretic performance of the specimens under low cycle repeated load is carried out by using ABAQUS.Firstly,according to the idea of "weak node strong component" and "strong node and weak component",two groups of 6 full-scale joint specimens are designed and analyzed by finite element method.Based on the experimental results of the research group,the effectiveness of the finite element results is verified.The results show that the "strong node" specimen has good seismic performance,similar to the eccentric support steel frame energy dissipation beam section.The ductility and energy dissipation capacity of the "weak node" specimen are superior to those of the ordinary concrete joint.Secondly,the hysteresis performance of weak joint specimens is analyzed on the basis of ensuring the correct finite element model.The parameters include the embedded length of steel beam,the width of flange,the strength of concrete and the ratio of axial compression.The results show that the embedded length of steel beam has the greatest influence on the bearing capacity of the joint,the width of flange of steel beam has the second influence on the joint bearing capacity,the concrete strength has little influence on the bearing capacity of the joint,and the axial pressure ratio can be ignored.Limited to the study in this paper,it is suggested that the embedded length of steel connecting beam should not be less than 420 mm,the ratio of shear wall thickness to flange width of steel diaphragm beam should not be less than 1.56,and the strength grade of concrete should not be higher than C50.The value of axial compression ratio meets the requirements of relevant specifications.Finally,based on the results of finite element analysis,the applicability of the existing research results of the mechanical model and the corresponding node bearing capacity formula is analyzed.The results show that when the effect of auxiliary reinforcement is not considered,there is a big difference between the existing calculation results of the joint mechanics model for the calculation of the bearing capacity of the joint.Through comparative analysis,it is suggested to refer to the Mattock-Gaafar joint mechanics model.On this basis,the calculation formula of the joint bearing capacity is modified,and the recommended formula for the calculation of the embedded length of steel beam is given with reference to the relevant codes in China,and the correctness of the formula is verified.