Study On Mechanical Properties Of Frame-Shear Wall Structure With Its Shear Wall And Column Connected By CFST Keys

As one of the important development directions of the world’s future buildings,assembled concrete structures have the advantages of high construction speed,energy efficiency,environmental friendliness,and low labor demand.At present,the connection of prefabricated concrete structural components mainly relies on connecting the stressed steel bars of the prefabricated components using a variety of methods,and then casting concrete or grout at the joints.The connection between the components requires relatively heavy wet work and the construction quality is difficult to control.Therefore,some researchers proposed the use of steel or Concrete-filled Steel Tube(CFST)to join prefabricated concrete components.So our research team proposed a new scheme of connecting prefabricated shear wall and prefabricated frame column in the assembled frame-shear structure with CFST keys,and conduct research systematically.It’s of great significance to explore the application of composite structure members in the connection of prefabricated concrete structures and promote its industrialization.The main work done and the according conclusions is as the following.The engineering feasibility of this connection method is discussed by means of test and finite element simulation.The test includes the direct shear test on the structure of wall and column connected by CFST keys and low cycle reciprocating loading test on single-layer plane frame-shear wall structure.The results show this kind of prefabricated structure reasonably designed has good seismic performance,and its bearing capacity and ductility are better than that of the cast-in-place structure,and the initial rigidity is almost the same as the latter.It can realize the design target of "prefabricated structure being equivalent to the cast-in-place structure".Thus it’s feasible in civil engineering.Based on the direct shear test model of the structure of wall and column connected by CFST keys,the influence of different factors on their direct shear mechanical properties is analyzed with finite element simulation method.The results show that:The main factors affecting the direct shear mechanical properties of the model are the section height and the length of CFST keys;The section width of CFST keys has large influence on its ductility;The thickness of CFST has certain influence on its shear bearing capacity and initial stiffness;The steel strength of CFST only has obvious influence on its ductility;The longitudinal distance between the CFST keys and the concrete strength of the reinforced concrete block has large influence on its initial stiffness;The concrete strength of the CFST keys and the steel strength of the reinforced concrete block has little influence on its mechanical behavior.Based on the model of single-layer plane frame-shear wall structure with its wall and columns connected by CFST keys,the failure characteristics,the feature of load-displacement hysteric curves and skeleton curves,the yield state of steel bars and steel tube,the rigidity degradation and energy dissipation capacity of it are analyzed by means of test and finite element simulation.The influencing factors on the structure are also analyzed.The results show that:The change of the number of CFST keys has little influence on the bearing capacity and initial stiffness of the whole structure,but it has great influence on the ductility and energy dissipation of it;The change of the thickness of steel tube and axial compression ratio has large influence on the load-displacement skeleton curves of the whole structure;It’s necessary to set CFST keys and reinforced concrete blocks simultaneously for the connection of wall and column in fabricated frame-shear wall structure.Based on the above analysis,how to assume the parameters of CFST keys in preliminary step are given,and the design method of bearing capacity of the connection is put forward.