Live load transverse distribution in a road slab-girder bridge made of FRP composite girders

The paper presents an analysis of the parameters of live load transverse distribution in the span of a road bridge that is made of four box FRP composite girders and a composite deck slab made of lightweight concrete. The parameters were determined experimentally and computationally using the orthotropic plate model included in the Cusens-Pam solution and also the numerical FEM model. The measured values of load transverse distribution factors and influence lines were determined during bridge load testing. A comparison of the measured and calculated load transverse distribution factors is shown on the basis of the analysis of the girders' deflection in their cross-section in the middle of the bridge span. As a result of this comparison, it was proved that the analytical model of the orthotropic plate and also the numerical shell-solid FEM model have a high compliance of load transverse distribution with the distribution obtained from the measurements. In addition, computational analysis and tests showed a sufficient flexural rigidity and high torsional rigidity of the bridge span (the bridge construction belongs to a group of structures with a low overall rigidity of k = 300 kN/mm), confirming that the FRP composite girders that were used for its construction can be an alternative to the concrete and steel girders that are commonly used in the construction of bridges.