The Analysis of the Internal Forces in Strengthened Old Concrete Bridge Subject to Vehicular Load by Transforming Simply Supported into Continuous System

In the past half century, large numbers of simply supported bridges were constructed in China; however, with the passing of years and the increase in the volume of transport, many of the bridges are out of normal service level and even gradually lose their bearing capacity due to overload or environmental influence. Therefore, some strengthening works have to be carried out in order for these old bridges to work well. Among the common strengthening methods, an efficient way to transform a simply supported into a continuous system is widely used in simply supported bridges with small or medium span. After the transformation of the system, the internal forces in the bridge are redistributed. This paper investigated, using the FEM software ANSYS, both the endogen forces of an old T-type bridge transformed from a simply supported to a continuous system under vehicular load. The result of the analysis indicates that the flexural moments in mid-span of all lateral T beams are significantly decreased and negative moments at supports are formed, while the shear forces in controlling sections are increased that are required to be reinforced based on the computation. In addition, after transformation, both longitudinal and lateral stiffnesses of T beams are improved that provides beneficial effects on the deflections of the bridge.