Research On Seismic Properties Of Prefabricated Truss-type Concrete Frame Joint

As the urbanization process is continuously advanced,and the pace of building industrialization is accelerated in China,in order to realize the transformation of construction industry of China,the energy-saving and environmentally friendly residences have increasingly become the goal and direction of our country in housing construction,and the new structures have emerged in endlessly.The truss-type steel reinforced concrete structure is a new type of structure encased in concrete,in which steel angles are used as the stress skeleton instead of steel bars,and the steel angles are welded with joint plates.This structure can not only improve the bearing capacity of components,but also save more steel and strengthen the sliding resistance.A new type of prefabricated truss-type concrete frame joint was put forward in this paper,and the experiments and theoretical analysis of its anti-seismic property were carried out;the results were as follows:(1)Low cyclic loading test was conducted on 6 specimens,and the hysteretic curve,skeleton curve,rigidity degeneration,energy dissipation capacity,angle steel strain and etc.of components were analyzed.The test results showed that the axial load ratio could influence the joint energy dissipation,ductility,stiffness degradation,and ultimate bearing capacity,namely.If the axial load ratio is greater,the ultimate bearing capacity will be higher,while the ductility and energy dissipation will slightly decrease,and the stiffness degradation will be quicker;the influence of cross diagonal web members in joint core area has great influence on the bearing capacity of components,and the ultimate bearing capacity,ductility and energy dissipation capacity of the components with cross diagonal web members are better than those without cross diagonal web member.(2)the ductile failure mode of beam-end bending failure was achieved,and the beam-end plastic failure happened in all the six components in the test,showing the good anti-seismic property,and achieving the design principle of "strong column,weak beam,strong joints".(3)ABAQUS finite element analysis software was used to establish the finite element model for the six components.The analysis results showed that the ultimate bearing capacity of test skeleton curve and simulation skeleton curve tallies with its corresponding displacement value,thus verifying the feasibility of finite element model.(4)The truss-type steel reinforced concrete beam-column middle-joint restoring force model was established in combination with the experimental data,the fitting contrast is made between the model skeleton curve and test skeleton curve;the results show that the two curves are relatively similar.Based on the stress mechanism of truss-type steel reinforced concrete joint design,the formula of shear-bearing capacity of joint core area as well as the design method of truss-type steel reinforced concrete joints is obtained.