Deflection Requirements for Bridges Constructed with Advanced Composite Materials

Many bridges in the United States have reached or are approaching the end of their useful lives. Since the 1940s, salt and other deicing agents applied to highways and bridges, coupled with inadequate maintenance funding, have led to the premature deterioration of many bridges. Growth of the United States economy and population has increased vehicular traffic volume and loads. For these reasons, the need exists for large-scale rehabilitation, strengthening, widening, and replacement of bridges. The financial cost to society to replace these bridges or to rehabilitate them conventionally is staggering. What is needed are low cost, durable methods of strengthening current bridges, extending their lives so that state departments of transportation may spread out the process of eventual replacement. In constructing new bridges, better materials or designs are needed so we may avoid tomorrow the consequences we are experiencing with today’s bridges. Polymer matrix composites offer that potential. A design methodology developed for composite bridges is based on limiting live load deflections. This paper focuses on the establishment of deflection limitations for bridges constructed with advanced composite materials, based on limiting response accelerations produced by the passage of truck traffic.