Assessments and preventions of the damages and their modes in the second and third spans of the RC highway straight girder bridge under surface blast using the FEM-SPH coupling

The blast threats have become a global safety concern for the ecosystems. Rigorous research using blasts over infrastructures improves the assessment methods, damages and failure modes, either experimentally or numerically. However, experimental blast analysis over a full-scale bridge is not feasible and is against the country's federal law. Alternatively, numerical analysis with experimentally validated parameters of prototype or scale models is better. Eventually, a bridge is one of the significant infrastructures that connect two conflict or geographically cut-off points for vehicle movements. Therefore, single or multispan full-scale bridge's impact analysis under blast is vital. Further, the literature address that coupled finite element method (FEM)- smoothed particle hydrodynamics (SPH) method yield better results at blast temperatures, and damage in the same span of the blast is primarily unrecoverable. Therefore, the current numerical investigation explores the assessments and preventions of the damage and their failure modes in the second and third spans, taking 16 numbers RC straight highway girder-bridge models under surface blast using FEM-SPH coupling with reflected air boundary and 5 mm thick non-Explosive Reactive Armour (nERA) as a protective material over entire bridge surface. The damage assessments of the bridge have been explored using blastwave propagation, interaction, effective plastic strain, particle-damaged contours, mass loss, and failure modes. Finally, the study recommends the application of blast- resistant barriers to provide safety and prevent the blast's primary and/or secondary effects.