Blast Load Effects on Highway Bridges. I: Modeling and Blast Load Effects

Numerous terrorist events during the last decade, including the 2001 attack on the World Trade Center, have heightened concern about the safety of bridges during intentional/unintentional blast load effects. Analysis of highway bridges under blast loads requires accurate generation and application of blast loads and good understanding of the behavior of components of a bridge during high strain rate loading encountered during blast loads. In this paper, a new approach for the application of blast loads on bridge components has been presented. This approach can apply realistic loads and can simulate both reflection and diffraction of blast loads. Using this approach, verification of simulation of blast loads in LS-DYNA has been carried out by using available blast tests on two types of beams. A high fidelity model of a typical three-span highway bridge has been developed for investigation of blast load effects on a three-span reinforced concrete bridge. It is observed that the range of demands imposed on bridge components during blast loads may be significantly higher than those during other extreme hazards, e.g., seismic, for which bridge components may have been designed. Detailed results on various failure modes of this bridge and seismic blast correlations using this model of the bridge are presented in the companion paper.