Mixed constraint modal method on nonlinear soil - structure interaction
the implementation method of the linear and nonlinear constraint modal synthesis method was analyzed in the soil-structure dynamic interaction progrom. According to the local nonlinear feature, the whole structure was divided into several linear and nonlinear sub-structures. Those linear sub-structures just require only one step to extract the characteristic matrices and reduce equation order, while for nonlinear sub-structures, they needed gradually to extract from the reduced order equivalent characteristic matrices. By assembling the above sub-structures, the order of whole structural characteristic matrices were reduced. For the nonlinear sub-structures, using piecewise equivalent linearization method in a small period of time, an executable program file to extract the characteristic matrices were edited by means of ANSYS secondary development tools UPFs and the simultaneous computation with MATLAB. Results show that the frequencies and dynamic response time history curves obtained by the above the method are in good agreement with those obtained from the ANSYS directly calculation method. Overall this method can extract the equivalent elastic-plastic feature matrices gradually, and it provides an effective method on deep research in the plastic phase by extraction of the gradually varied characteristic matrices.
School of Civil Engineering, Tianjin University／Key Laboratory of Coastal Civil Engineering Structure and Safety, Ministry of Education, Tianjin 300072, China
Abstract：the implementation method of the linear and nonlinear constraint modal synthesis method was analyzed in the soil-structure dynamic interaction progrom. According to the local nonlinear feature, the whole structure was divided into several linear and nonlinear sub-structures. Those linear sub-structures just require only one step to extract the characteristic matrices and reduce equation order, while for nonlinear sub-structures, they needed gradually to extract from the reduced order equivalent characteristic matrices. By assembling the above sub-structures, the order of whole structural characteristic matrices were reduced. For the nonlinear sub-structures, using piecewise equivalent linearization method in a small period of time, an executable program file to extract the characteristic matrices were edited by means of ANSYS secondary development tools UPFs and the simultaneous computation with MATLAB. Results show that the frequencies and dynamic response time history curves obtained by the above the method are in good agreement with those obtained from the ANSYS directly calculation method. Overall this method can extract the equivalent elastic-plastic feature matrices gradually, and it provides an effective method on deep research in the plastic phase by extraction of the gradually varied characteristic matrices.
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