Applicabiliy of the simplified load distribution factor equation to PSC girder bridges

AASHTO LRFD specifications first introduced a new load distribution factor equation as a result of the NCHRP12-26 project. However, this equation involves a longitudinal stiffness parameter, which is not initially known in design and thus introduces an iterative procedure. Practicing engineers perceive this need for an iterative design procedure as the major impediment to wides pread acceptance of the AASHTO LRFD equation. Recently, a non-iterative simplified equation based on the AASHTO LRFD formula was developed for steel girder bridges. The applicability of this equation to Prestressed Concrete (PSC) girder bridges is investigated in this paper. A total of 17 PSC girder bridges are selected and analyzed using a sophisticated finite element model. It has been found that the new simplified equation produces LDF values that are always conservative when compared to those obtained from the finite element analyses and are generally greater than the LDF obtained using AASHTO LRFD specification. Therefore, the simplified equation provides a simple yet safe specification for LDF calculation.