LU GIRDER DEVELOPMENT

On behalf of the LA DOTD and as part of the continuing effort in the development of the Bridge Design and Evaluation Manual, SDR designed an optimized U girder as well as formulated live load moment and shear distribution factors for the proposed U girder with depths exceeding 65 inches, providing 33 sheets of standardized LU girder plans. The study identified the FDOT U girder to be an ideal candidate for further development based on ease of fabrication, cross sectional efficiency, and transportation purposes. A parametric study involving finite element models was conducted for the proposed LU-72, 78, and 84 girder sections. The study considered several parameters known to affect live load distribution, including span length, girder spacing, girder stiffness, and overhang width. This parametric study incorporated 96 primary FE models and 18 additional models to expand the study to include additional overhang widths. The results of the study yielded live load distribution factors exceeding limitations of AASHTO specifications to use in lieu of the AASHTO equations for the new proposed girder sections.