Abstract:In the dynamic analysis of underground structure,the constraint to structures caused by the surrounding soil is often simulated by the virtual parameters,such as virtual mass,stiffness and damping parameters. Because of these virtual parameters,the model of underground structure is different from that of ground structure,which will cause traditional methods to fail in solving underground structure. Therefore,two approaches are presented—one method is applied to shear-type underground structure which can identify the structural parameters and virtual parameters at one step;and the other method which can be used to estimate common system with multi-degree freedoms by two step. In the first step,the structural parameters are identified;and in the second step,the virtual parameters can be estimated by using the structural parameters identified before. At last,a numerical example of shear-type building is applied;the results show the feasibility and efficiency of the method.