| A number of recently constructed bridge approach slabs using an articulation at mid span and the wide flange terminal anchorage system have experienced settlement at their expansion joints. This problem is more commonly referred to as the bump at the end of the bridge. This study investigated reasons for the bumps and recommended ways to improve the current situation.; To find out possible causes of the bridge approach slab problem, literature review, questionnaire survey, and a visual inspection for 18 Houston sites were conducted. Based on the results, two bridge sites in Houston, Texas, were selected for detailed investigation. An extensive series of laboratory and field tests were performed at each site. The main causes of bump at two study sites were compression of embankment soil and natural soil, and poor compaction of embankment soil.; The finite-element computer program ABAQUS was used to evaluate behavior of the current approach slab design and of a possibly more effective design. The results show that the transition zone is about 12 m with 80 percent of the maximum settlement occurring in the first 6 m for a uniform load case and the optimum width of sleeper and support slabs is 1.5 m.; A new approach slab which is 6 m long and has one span from the abutment to a sleeper slab was proposed based on accumulated data. It is designed to carry the full traffic load without support on the soil except at both ends; the support slab is removed and the wide flange is kept on the embankment side as a temperature elongation joint.; The BEST device (Bridge to Embankments Simulator of Transition) was built to simulate the bump at the end of the bridge problem. It is a 1/20 th scale model of the typical transition and the dimension was determined from dimensional analysis. Multiple BEST tests were conducted using a range of parameters and several influence factors were derived. A computer program was developed which uses the influence factors to predict the bump size from the beginning stage of embankment construction. |
