| Abstract: |
Rapid vertical urbanisation in seismically active Indian cities has produced dense clusters of buildings separated by gaps far narrower than code-mandated values, while the same clusters are increasingly exposed to accidental and malicious explosion events in congested commercial precincts. This paper presents an empirical, data-driven investigation of the dynamic performance and impact-mitigation behaviour of closely spaced reinforced-concrete buildings subjected to seismic and explosion-induced loading, considered both separately and in combination. A parametric database of 216 nonlinear time-history simulations was assembled for three building pairs of 10, 15 and 20 storeys, nine separation gaps between 0 and 160 mm, eight recorded ground motions scaled to four intensity levels, and blast scenarios generated for charge weights of 50–250 kg TNT at standoff distances of 10–20 m. Impact was represented by a nonlinear Kelvin–Voigt contact element calibrated against reported experimental restitution coefficients, and blast demand was applied as a Friedlander pressure pulse on the exposed façade. Results are reported through five statistically analysed datasets covering peak pounding force, inter-storey drift, floor acceleration amplification, mitigation-device effectiveness and fragility. The data show that pounding amplifies drift by up to 111 percent and floor acceleration by up to 3.4 times at the impact level, that the combined seismic-plus-blast case shifts the median extensive-damage capacity from 0.31 g to 0.22 g, and that a viscoelastic coupling link reduces impact force by 67 percent and drift by 51 percent. Regression analysis yields a gap-demand relation of practical value, and the study concludes that gap provision alone is an inefficient mitigation strategy compared with energy-dissipating structural coupling. |
