Affiliations: Structural Engineer, Dewberry Inc., Bloomfield, NJ, USA | Department of Civil and Environmental Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA | Senior Engineer, Severud Associates, New York, NY, USA
Abstract: The vulnerability of bridges to blast hazards is an increasing concern for engineers and governments agencies, and the public. Blast hazards on structures can be classified as either accidental hazards or intentional blast attacks and structures should be protected to mitigate these hazards. Current bridge design codes do not account for blast loading and there is a need for guidelines for designing structures such as bridges and other structures to resist blast loads. The individual response of structural elements subjected to blast loads depends mainly on the standoff distance, charge weight, and the distribution of the blast pressure along the length of the loaded member. Structural components such as bridge piers subjected to blast hazards along with their connections should be designed to have considerable ductility and energy absorption capacity. This paper presents a simplified design method for members subjected to unconfined blast loads such as bridge piers. Estimating blast loads on a member due to specific blast scenario is complex. To simplify the analysis, dynamic blast loads were transformed into equivalent static loads and simplified blast load response spectra were developed based on approximate blast pressure distributions. Blast response spectra can be used to analyze and design individual structural components subjected to blast loads in flexure, estimate the required ductility, and estimate the minimum standoff distance for the different probable blast charge weights. For complex critical structures, more rigorous analysis is needed including the global response of the structure.
