Validation of a numerical model based on dynamic centrifuge tests and studies on the earthquake damage mechanism of underground frame structures

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A series of dynamic centrifuge tests were performed to analyse the seismic response and failure mechanism of the underground frame structures. In the model test, the model structure experienced complete collapse, which has rarely been reported in previous studies. This study aimed to obtain an effective numerical model based on physical tests that could properly simulate large deformations or even the collapse of soil-structure systems under earthquake loads. The tests were numerically analysed via a full dynamic time history analysis considering the non-linear properties of the material and contact. The process of establishing numerical model and the method of determining material parameters were elaborated. The numerical results were compared to experimental data to validate the effectiveness of the numerical model. Finally, the calibrated numerical model was used to carry out further research on the seismic damage response and failure mechanism (i.e., collapse damage) of underground structures. Some of most important insights based on the model test and numerical results are as follows. The top and bottom of the column of underground frame structure were determined to be the weakest positions under earthquake loading conditions and were vulnerable to bending-shearing failure. The vertical earthquake load could significantly increase the axial forces on the columns and then reduce their horizontal deformation capacity. The columns subjected to high axial compression were prone to complete brittle failure under a relatively strong horizontal earthquake load and caused the overall collapse of the underground frame structure. Therefore, the underground frame structure could avoid complete collapse under a strong earthquake load as long as the column was free from damage and provided sufficient vertical support.