In-structure shock of underground structures: A revisit with experimental investigation

In-structure shock of underground structures subjected to ground shocks is investigated, both theoretically and experimentally. In the theoretical prediction, the ground shock is simplified to a triangular pulse with a rise time. It is found that the acceleration time history of the structure when the rise time of the ground shock is considered is significantly different from that when it is neglected. A small scale test is designed and conducted to validate the theoretical prediction. The comparison of the measured and predicted acceleration time histories suggests that the theoretical prediction with ground shock rise time considered is more reasonable. Further, shock response spectra for the equipment attached to the underground structure are established and a case study indicates that in-structure shock level of the devices predicted by the model with ground shock rise time is higher than that predicted without consideration of the ground shock rise time. It is shown that the present assessment of in-structure shock is reasonably accurate and it can be used for a preliminary design of underground structures where in-structure shock is concerned.