ABSTRACT
An adequate evaluation of the load-carrying capacity of a bridge is an important issue to determine the allowable traffic loads on a bridge. The design and construction of modern highway bridges are based on the load effect of standard design trucks. However, constructed bridges may be subject to nonstandard truck loads such as military trucks or logging-industry trucks. The flexural response of a bridge under such nonstandard loads may be different from that under the standard truck load. Inadequate predictions of the load effect may cause serious damage in the bridge. Because the traffic loads in bridges are not uniformly distributed to the individual components of the superstructure, one of the first steps to evaluate the capacity of the bridge superstructure to carry nonstandard vehicles is to make a realistic assessment of the lateral load distribution to the structural components such as main girders. Numerous research efforts have been made to predict the load distributions on a bridge (Zokaie 2000; Song et al. 2003; Kim et al. 2008). Zokaie et al. (1991) conducted an intensive survey of over 800 bridges across the United States and developed design formulas to predict the lateral load distributions. The American Association of State Highway and Transportation Officials (AASHTO) adopted the developed formulas for a new version of the bridge code called the Load Resistance Factor Design (LRFD) Bridge Design Specifications (AASHTO 1994, 2007). The applicability of the design provisions should be
reviewed when a bridge is subjected to nonstandard truck loads, given that the formulas have been developed based on the standard trucks. This paper examines the applicability of the live load distribution factors of the AASHTO LRFD to nonstandard military truck loads.
