Maximum Response Ratios of Three-Span Continuous Bridge Girders Due to Thai Trucks and HL-93 Live Loadings

Abstract

Abstract

The American Association of State Highway and Transportation Officials (AASHTO) has recently issued the design provisions using the method of Load and Resistance Factor Design (LRFD) for current bridge design practices. The vehicular live loadings designated as HL-93 has been introduced for the design purposes. Nevertheless, Thai truck loads rated by the Department of Highways are different from those of HL-93. This study was then focused on the maximum responses of three-span continuous bridge girders with the total length ranging from 90-180 meters due to Thai truck loads and those of HL-93. A comparison on the maximum shear ratios and bending moment ratios of the continuous bridge girders was made. The results revealed that, in each type of bridge configuration, the maximum shear and bending moment were primarily caused by the truck with semi-trailer having a total weight of 45 tons. From the structural analysis, the shear ratios and the moment ratios were found to vary between 0.974-1.413 via the various bridge girder span lengths. Furthermore, the ratios in some configurations of continuous bridge were found to be 23.25% larger than those from the previous study on the simply supported girder-type bridges having the same span length. These ratios could be applied as multipliers to HL-93 in order to obtain the required strength of bridges that is compatible to Thai truck loads.