Live Load Distribution for Steel-Girder Bridges


Grillage method is used here to determine girder distribution factor (GDF). STAAD Pro. 2006 program is used here to represent grillage and solving for (GDF). Different GDFs are adopted by AASHTO LRFD based on the National Cooperative Highway Research Program (NCHRP) 12-26 and the results compared with formulas given by AASHTO Standard. Three different composite steel bridge superstructures are considered with girder spacing (1.22, 2.44 and 3.66 m). To compute GDF in theconsidered bridges subjected to one truck, the vehicle is placed on each bridge such that the load effect in the girders is maximized. If compared with Finite element method, the modified grillage was found to be simple, efficient and having practical accuracy in the analysis of bridge decks in determining GDF factors.