Study On Seismic Performances Of Assembled Concrete Semi-Rigid Beam-to-Column Connections

Precast concrete structure is in accordance with the Modernization Housing Industrialization development.And the study on joint connection is the key issue to promote the development and application of Precast concrete structure.In this paper,based on the properties of semi-rigid connection and low-rise multilayer assembled buildings,two types of fully assembled reinforced concrete beam-to-column connections are proposed,which come from top and seat angle connections and end-plate connections of steel frame joints.The connections are formed by the prefabricated beams,columns and stiffened angle steel components or end plate components through the high-strength frictions bolts.The angle and end plate can provide energy-dissipation capability through deformation under the earthquake.Moreover,the joints damage is concentrated in the energy consuming parts(angle or end plate)and the local beam end,which the connection can be easily reparation,quickly recovery and implement industrial production.In this paper,the connection mechanism and seismic performances of two types of semi-rigid joints under reversed low-cyclic load are studied through the quasi-static test,theoretical analysis and numerical simulation.And the simplified calculation method of moment-rotation curves of joints has been proposed.The main contents are as follows:1)The low-cyclic load test of the top and seat angle connections were carried out,and the seismic performances was aslo analyzed.The experimental results showed that the angle joint has good energy dissipation capacity.Finite element analysis of the angle steel joint under reversed low-cyclic load has been performed to verify the reliability of the finite element method.2)The seismic performances of the connections under low-cyclic load were analyzed and compared by using Abaqus,including one cast-in-situ connection,one angle steel connection and end-plate connection.The simulation results show that: the angle steel connection and end-plate connection belong to semi-rigid joints.Compared with the traditional cast-in-suit joint,the damage of the assembled joints is mainly concentrated in the steel components and local beam end.And two types of the assembled joints have better energy dissipation capacity and deformation capacity than the cast-in-situ connection,while the bearing capacity of assembled joints are both lower than the castin-suit joint.3)Several parameters which have a significant impact on the mechanism of the assembled joints are analyzed by using Abaqus.The simulation results show that the thickness of steel components has great influence on the mechanical properties,increasing thickness can significantly improve the rotational stiffness,flexural capacity and energy dissipation capacity.If the thickness is larger,the bolt is directly pulled off or slide between the beam and angle steel,the good rotational deformation of the semi-rigid connection is wasted.While the thickness is smaller,the deformation of end-plate or angle steel is larger,the bearing capacity is lower and the accumulated damage is serious,which lead to the joints early destruction4)Through theoretical analysis,the simplified calculation method of momentrotation curves of the assembled joints was proposed.The calculated moment-rotation curves agree well with the simulation results,which are overall lower and are basically consistent in the elastic,and can provide reasonable theoretical basis for the application of assembled joints in pratical engineering.