Soil–structure interaction effect from blast-induced horizontal and vertical ground vibration

Abstract

Although the effect of soil–structure interaction (SSI) due to earthquake has previously been studied, the same cannot be said of blast-induced ground excitation. The latter involves both horizontal and vertical excitation in which the dominant frequency range is higher and the duration shorter than that caused by earthquake. An accepted model for horizontal excitation is adopted for the vertical excitation case to study the SSI on the modal and structural response. Based on the numerical results from a five-storey plane frame with base mass to superstructure mass ratio of 0–0.4 on soil with shear wave velocity ( V s) from 50 to 5000 m/s subjected to dominant frequencies from 10 to 300 Hz, it is found that (i) the soil acts as a low pass filter and mainly affects the top horizontal and vertical displacements through the fundamental mode of vibration; (ii) increasing base mass provides inertia against the input excitation and attenuates the high frequency component thus affecting the base shear and axial force more significantly; (iii) higher V s of the underlying soil is associated with stiffer soil and hence has decreasing SSI.