Stochastic dynamic response of short-span highway bridges to spatial variation of blasting ground vibration

摘要

This study carries out a parametrical stochastic analysis of a short-span highway bridge to spatially varying blast ground motion and exhibits wave passage, loss of coherency and attenuation effects of spatial variation of blast ground motion at the rock medium. Wave passage time delay effect is due to differences in arrival times of shock waves at different locations and loss of coherence of shock waves is due to multiple reflections refraction as they propagate through the highly inhomogeneous rock medium. The fully coherent model is considered to take into account the loss of coherency of blast ground motion. Furthermore, before the power spectral density and cross spectral density functions of shock time histories are produced, the attenuation of shock waves are taken into account in this study. A short-span highway bridge is considered in order to be analyzed for spatially varying blast ground motion. Different charge weights and distances from the charge center are considered to investigate the effects of blast ground motion on the bridge. The comparisons of results of the shaded image counters and one standard deviation as well as power spectral densities of the response of the highway bridge according to the three different charge weights with the three different charge centers are investigated for numerical calculations. The results of the analyses revealed that spatial variation of blast ground motion significantly affects stochastic responses of short-span highway bridges.