The Research And Discussion On The Role Of Soil-structure Dynamic Interaction In The Control Of Energy Dissipation

In recent decades, with its rapid development, the technology of energy dissipation has become an effective measure to decrease the reaction on structures by earthquake. There has been a growing interest in the engineering applications of energy dissipation devices for earthquake resistant design of buildings owing to the advantages of safety, reliability, wide range of application and economization. However, due to the complexity of the soil - structure dynamic interaction analysis, structural engineers often suppose that the base is fixed when designing the structural systems with energy dissipation devices. This is applicable if the base is of high rigidity, but not reasonable when the base is relatively soft. And adding these devices into buildings not only significantly increases the structural damping, but also increases the structural stiffness, so that the fundamental frequencies of buildings are changed. Therefore, it is necessary to research and discuss the role of soil– structure dynamic interaction in the control of energy dissipation.In this paper, according to the performance of energy dissipation devices (viscoelastic dampers), computational model and dynamic equations were established for the structural systems with energy dissipation devices, then additional stiffness and damping matrix were derived. Combined with the assumption of elastic half-space, 2-DOF lumped-parameter model was simplified to consider the foundation soil. Dynamic equations were established for the structural systems with energy dissipation devices when soil-structure interaction was taken into account, and a MATLAB computer program was developed with the complex mode method to solve these equations. Based on a casting reinforced concrete 10-storey frame structure, the effect of soil-structure interaction on the seismic response of the structural systems with energy dissipation devices was studied in which three earthquake records were used.Through the analysis of theory and numerical examples, the following conclusions are summarized: First, natural frequencies and overall modal damping ratios of building systems with energy dissipation devices increase with the increase of energy dissipation devices when these systems are assumed to be fixed. Energy dissipation devices can effectively reduce the seismic response of these building systems. Second, the existence of soil - structure interaction reduces the fundamental frequencies of building systems, and prolongs the fundamental periods. On the same base the fundamental periods and the story maximum displacement of building systems decrease with the increase of damping. Soil - structure interaction reduces the effectiveness of the energy dissipation devices in increasing the damping of systems. It is confirmed that after considering soil - structure interaction energy-consuming role of soil can be taken full use of, so the purpose to reduce the number of energy dissipation devices and the construction investment is achieved. Also the significance of the interaction is demonstrated.