Live load distribution equations for integral bridge substructures

In this study, live load distribution equations (LLDEs) for integral bridge (IB) substructures are developed. For this purpose, numerous 3-D and corresponding 2-D structural models of typical IBs are built and analyzed under AASHTO live load. In the analyses, the effect of various superstructure and substructure properties such as span length, girder spacing, girder stiffness, abutment height, pile size, pile spacing and foundation soil stiffness are considered. The results from the 2-D and 3-D analyses are then used to calculate the live load distribution factors (LLDFs) for the abutments and piles of IBs as a function of the above mentioned properties. LLDEs are then developed to estimate the live load moments and shear in the abutments and piles of IBs using these LLDFs and nonlinear regression analysis methods. It is observed that the developed LLDEs yield a reasonably good estimate of live load moment and shear in the abutments and piles of IBs.