Experimental Study On Seismic Behavior Of Semi Seam Coupling Beams

Shear wall structure is widely used in high-rise buildings.As a very important component of shear wall structure,coupling beam is the first line of defense against earthquake of coupled shear wall structure,which damages firstly when rare earthquake occurs.So that it follows the principle of strong column and weak beam.By using the plastic hinge rotation at the end of the coupling beam a large amount of seismic energy was consumed to achieve the purpose of protecting the building.Due to the need of lateral stiffness of structure,the span-depth ratio of coupling beams is often small in practical engineering.In order to ensure the safety of the structure,the seismic design of the coupling beam is particularly important.In this paper,we propose a new cross section form of coupling beam-semi seam coupling beam.The middle section of coupling beam was weakened by setting a half-pass seam in the middle of the beam.In low intensity earthquake,the semi seam coupling beam can play a full capacity as ordinary coupling beam to ensure the lateral stiffness of the structure.When the high-intensity earthquake occurs,concrete at the semi seam will damage firstly and then quit working.Afterwards,the semi seam coupling beam converted into the double beam,improving the ductility and deformation of the component,thereby delaying the damage of the component.The research content of this paper includes three aspects:(1)Four coupling beams were designed,including two semi seam coupling beams in different span-depth ratios,a lintel beam and a dual coupling beam,and made on-site and naturally cured.The low – frequency cyclic loading test of four beams was carried out.The characteristics of concrete stain distribution,the characteristics of rebar stain distribution,and the horizontal displacement of beam were measured during the test.And the development and failure of the beam in the quasi static test were also recorded.(2)The effects of hysteresis loop,skeleton curves,load-carrying capacity,energy dissipation capacity,stiffness degradation,displacement ductility and intensity of the semi seam coupling beam under low – frequency cyclic loading test were studied by using the experimental data.In contrast with other forms of cross sections of coupling beams,the loaded property and mechanics regularity of semi seam coupling beam were analyzed.The experimental results show that: 1)The failure process of coupling beams undergoes three stages: elastic stage,yield stage and failure stage.Each stage has different destructive patterns and stress characteristics;2)The semi seam coupling beam can improve the load-carrying capacity of the components,improve deformation and flexibility of the structure and delay components damage;3)By increasing the span-depth ratio of the coupling beam,the energy dissipation capacity and ductility of components can be improved effectively.The bending failure takes majority in the failure of coupling beam with the span-depth ratio of 1.5.(3)The classification of the nonlinear analysis in ABAQUS was introduced in this paper.And numerical analysis of 4 kinds of coupling beams with different cross sections is carried out by using ABAQUS to study the mechanical behaviors of 4 coupling beams under low – frequency cyclic loading test.Comparing the experimental results with the finite element analysis results,the crack development process and seismic performance of semi seam coupling beams,common coupling beams and dual coupling beams are analyzed,which gives a comprehensive understanding of the seismic performance of semi seam beam.