Dynamic assessment of partially damaged historic masonry bridges under blast-induced ground motion using multi-point shock spectrum method

We studied the partial damage effects on historic masonry bridges exposed to blast-induced ground motion. For this purpose, a historic masonry bridge in Turkey was selected to estimate its shock spectral behaviour. In order to determine these results, first, various damage was created on the restored bridge finite element model. This damage was generally selected by searching for damaged historic masonry bridges in the literature. Various critical regions on an example bridge were detected and corresponding regions were removed from the restored finite element model. Thus, partially damaged historic masonry bridge models were obtained. Dynamic calculations of the bridge are presented by using the multi-point shock response spectrum method obtained from ground motions due to a blast load. Acceleration time histories of blast-induced ground motions are obtained depending on a deterministic shape function and a stationary process. Shock response spectra determined from ground shock time histories are simulated using a MATLAB-based BlastGM computer program developed by us. The frequency-varying shock response spectra are applied to each support of the two-span historic masonry bridge. The influences of various charge weights and distances from the charge centre are also investigated in the analyses. The results from the analyses demonstrate the importance of partial damage on the historic masonry bridge, blast-induced ground motion effects, and charge weight and distance from the blast centre.