Blast load analysis of concrete-steel composite bridges : focus on shear connectors of slab-beam intersections

Abstract

In the present context, increasing attention is being paid to the structural response of infrastructure under blast loading, with bridges recognized as particularly vulnerable due to their exposed locations and essential role in transportation networks, economic stability and emergency operations. This research focuses on concrete-steel composite bridges, which are widely used in urban and highway networks, yet lack explicit blast resistance provisions in current Eurocode 4 design standards. Unlike previous studies that have mainly examined the effects of blast loads on individual components such as slabs, girders, and piers, this study addresses the blast response at the critical slab– beam intersection locations particularly susceptible to localized failure during explosive events. A representative concrete-steel composite bridge, designed according to Eurocode guidelines, was selected as the basis for a detailed numerical investigation. A detailed numerical framework was developed using LS-DYNA with CONWEP blast loading and verified through a three-stage validation process involving a reinforced concrete slab, a steel girder, and the slab–beam interaction mechanism. Building on the validated modeling approach, a progressive blast analysis was performed, beginning with isolated slab and girder models, followed by a combined slab–girder system without shear connectors and a full composite model with shear connectors to simulate realistic composite action. Key results demonstrate that the inclusion of shear connectors significantly improves blast resistance by enabling effective load transfer, reducing localized damage at the slab–beam interface, and promoting controlled redistribution of blast energy across the composite system. A comprehensive parametric study was conducted by varying explosive charge mass, standoff distance, and stud row spacing to evaluate how these parameters influence the blast response of the bridge and to highlight the effectiveness of current Eurocode design standards. The blast analysis results were compared with key Eurocode design resistance values, including mid-span cross-section shear, stud connector shear, and longitudinal interface shear. While several scenarios remained safely within Eurocode limits, localized exceedances were observed under extreme explosive loading combined with wider stud spacing, particularly at blast-proximal locations. These findings confirm the reliability of current Eurocode provisions for moderate blast scenarios while highlighting the need for optimized connector layouts and explicit blast-resistance considerations to enhance the resilience of composite bridge slab– beam intersections under severe explosive events.