Analyze and calculate the Live Load Distribution Factor for Simply-Span Reinforced Concrete I-Beam and T-Beam Bridges

Abstract

In designing simple-span beam bridges such as I-beam and T-beam structures in road and highway construction, the bridge superstructure is a spatial structure composed of the main girders, the deck slab, and the system of connections between the main girders. The main girders are the primary load-bearing components, and to calculate internal forces within the girders, it is necessary to determine the load distribution factors for these girders. To conduct a comprehensive study, the authors calculated the live load distribution factors using formulas from Vietnamese Standard 11823-4:2017 and performed structural analysis with Midas Civil software based on a spatial model for supported I-beam and T-beam bridges. We then compared the results from these two methods. Findings indicate that the load distribution factors for moments and shear forces calculated using Midas are generally higher than those obtained from the formulas in Vietnamese Standard 11823-4:2017 in regions between transverse girders, such as L/8,3L/8, and near supports for shear force distribution factors. The discrepancies range from (7.92% to 36.1%) and (32.82% to 118.71%), respectively. However, at sections with transverse girders, such as L/4 and L/2, the calculated distribution factors are lower, with differences ranging from (-14.72% to 0%) and (-20.18% to -1.62%), respectively. Thus, significant discrepancies at specific positions should be carefully considered in the design calculations of simply supported reinforced concrete I-beam and T-beam bridges.