Effect of blast location and explosive mass on the dynamic behavior of a bowstring steel highway girder bridge subjected to air-blast

Abstract

Steel bridges are preferred for their lesser construction time and are used in territorial border areas, to develop road connectivity between neighboring countries, and also in the existing busy railway tracks to construct underpass and roads over bridges. Bridges are also quite commonly enquired in the Indian railway network for the railway tracks to cross over the nullas and rivers. Thus, steel bridges are also the part of infrastructural lifeline system of a country. The safety performance of such structures under explosive loading during warfare and subversion too is of serious concern to researchers, engineers, and other government officials. A few research papers addressing the dynamic behavior of steel bridges subjected to explosive loading are available in the literature. The objective of this study is to simulate the behavior of a bowstring steel girder bridge using the ABAQUS nonlinear finite element analysis software and investigate its response under air-blast loadings considering various detonation scenarios in terms of location and mass of the explosive charge. Johnson-Cook (J-C) damage model has been adopted to simulate the non-linear behavior of the steel. The main parameters affecting the behavior of bridge under blast load above the surface are investigated such as explosive weight (W), the distance from the explosion source to bridge (S), and location of explosion. The blast load is modelled as a pressure function of the stand-off distance and the equivalent mass of TNT. The load-carrying mechanism, stress profiles, and dynamic responses such as maximum displacement are discussed and compared. Based on the computed results, the most critical location of the explosives is assessed. It has been found that the severe eccentric explosive loading on the deck other than at the supports is found detrimental and makes the bridge almost irreparable. Damage to the bridge is directly proportional to the explosive weight and inversely proportional to the standoff distance.