Analysis Of Blast Loads On Bridge Substructures

Abstract

The design of structures to resist blast loads has traditionally been considered only for essential government buildings, military structures, and petrochemical facilities. Until recently, however, little attention has been given to bridges. One strategically placed truck bomb on a critical bridge could result in significant loss of life, severe structural damage, and devastate an economy. Recent terrorist threats to bridges in California and New York have demonstrated the vulnerability of our transportation infrastructure and reinforced the need for bridge security. This paper summarizes the results of ongoing research to develop performance-based blast design standards tailored specifically for bridges. The goal of the research is to investigate economical, unobtrusive and effective methods to mitigate the risk of terrorist attacks against critical bridges. The potential effects of blast loads on bridge substructures are presented, and structural design and retrofit solutions to counter these effects are discussed. Case studies demonstrate the use of simple models to analyze concrete piers. The modeling concept, determination of peak overpressures, and inherent assumptions are described, and empirical deformation-based damage criteria that are used to estimate the level of damage are presented.