Study On Influence Of Material Damping On Dynamic Response Of Steel And Reinforced Concrete Structures

Damping is not only the parameter characterizing the energy dissipation in structure vibration systems, but also an important factor affecting the dynamic and seismic response of structures. It is difficult to obtain the uniform understanding about damping until now for its comprehensive and complex mechanism.In real engineering, the damping values of structures are usually taken as constants according to composing material or Rayleigh damping. But these work only based on material without considering other structure factors are not reasonable. Rayleigh damping is only set up for decoupling in computation without clear physical meaning. As damping changing with stress and amplitude changing is considered in complex damping model, this agrees well with real stress condition of material under forced vibration, so complex damping model is the best description of damping character of the most engineering material.Viscous damping model and complex damping model are used to calculate the dynamic response of RC frame structures under seismic waves, and the contrast of the results is made in this paper. It is found that for different reinforced concrete frame system, considering different protected earthquake intensity, when various seismic waves are input, the maximal value of displacement response or acceleration response calculated under complex damping model is greater than that of viscous damping model. It is safer to calculate structure dynamic response under complex damping model in view of design.In addition, stress related complex damping model is also used to calculate the dynamic response and material damping value of steel beam, RC beam, steel frame and RC frame structures, and the obtained dynamic response results is analysed and contrasted with the dynamic response calculated under viscous damping model. It is found that the maximal value of displacement response or acceleration response calculated under complex damping model is greater than that of viscous damping model either; the material damping value increases when the stress increases, this characteristic is advantageous to increase energy dissipation of structure, and it is effective to control response amplitude of structure vibration.