Performance of bridge approach system under a moving tandem load-numerical analysis

Abstract

With one end supported by the sleeper slab and the other end supported by the bridge abutment, the approach slab provides a smooth transition between the bridge abutment and its adjacent pavement. Therefore, the sleeper slab, embankment soil, and bridge abutment support the truckload on the approach slab together. However, load distributions among these three supporting components have not been investigated thoroughly yet, especially, as the truckload approaches the bridge. In this study, a simulation model was constructed and validated based on a field case study. Then, the performance of the pavement, sleeper slab, and approach slab (i.e., the approach system) was explored as a tandem load approached the bridge abutment. Finally, the effects of some parameters on the approach system performance were investigated and these parameters included the embankment and foundation soil elastic modulus, connection type between the approach slab and bridge abutment, pavement and approach slab thickness, sleeper slab layout, and sleeper slab width. According to this study, increasing the pavement and approach slab thickness and integrally connecting the approach slab with the bridge abutment increased the load transferred to the bridge abutment; while increasing the foundation soil elastic modulus decreased the load transferred to the bridge abutment. In addition, when placing one-half of the sleeper slab under the pavement, contact stresses under the sleeper slab were more uniform and smaller than those when placing one-third or two-thirds of the sleeper slab under the pavement. Furthermore, a wider sleeper slab resulted in more load transferred to the sleeper slab but smaller contact stresses under the sleeper slab.