The Research On Seismic Behavior Analysis And Design Of Rocking Truss-steel Frame With Brb Or Viscous Dampers

Seismic behavior analysis and design of rocking truss-steel frame with buckling restrained brace(BRB)or viscous Dampers were studied by theoretic analysis as well as finite element simulation.A design method towards Direct Displacement-Based procedure for rocking trusssteel frame with dampers was proposed.The detailed research content are as follows:Firstly,according to whether dampers provide additional stiffness for structural systems,distributed parameter model was used to derivate lateral profile distribution of structural system.The relationship between displacement ductility coefficient and equivalent damping ratio of the structure system is deduced by the principle of equal energy.A design method based on the optimal strength ratio is proposed for rocking truss-steel frame with buckling restrained brace(BRB)or viscous Dampers,ensuring the structural system to obtain better energy dissipation performance.Structural systems with dampers of different design strengths was analysed with application of ABAQUS Finite Element Analysis Software,The analysis shows that the structural system with the optimum strength ratio has a prominent performance in reducing the input energy of ground motion and improving the energy dissipation capacity of the structural system.Secondly,A direct displacement-based seismic design method for a controlled rocking structure system with viscous dampers is proposed,in which the moment resistance frame is used as the design lateral displacement profile.Compared with buckling-resistant braced dampers,viscous dampers have full hysteretic loops,better energy dissipation performance and better performance in reducing the dynamic response of structures without changing the basic period of structural systems.Finally,ABAQUS finite element analysis is used to compare the seismic performance of the controlled and uncontrolled rocking structures with dampers.The results show that the failure modes of the controlled and uncontrolled structures have changed the moment resistance frame.The results show that both the controlled and uncontrolled structural systems have changed the failure modes of ordinary flexural frames,and realized the failure modes of lateral displacement and overall yield mechanism,which are dominated by first-order modes.For the maximum inter-story displacement angle,displacement ductility coefficient and energy dissipation performance of the structural system,the improvement is obvious.