Estudio de la problemática estructural de las losas de transición.Interacción terreno losa

Structural Study of the Problems Affecting the Bridge Approach Slabs, Extension to the Soil-Slab Interaction

Approach slab is the most common solution in roads to provide a continuous transition between the bridge deck and the embankment. The bridge abutment usually shows no settlement; the slab is jointed to the abutment and supported on the embankment that suffers some settlements. The slab is designed to get an acceptable slope change. Under normal conditions, with controlled embakment settlement and well done construction, the approach slab shows a satisfactory behaviour, but often problems appear that disturb travellers comfort and cause important maintenance costs. This situation focuses the attention of American and European roads authorities towards this question. Now days most approach slabs are designed applying guidelines for the design and construction. This is the situation in many States of USA, France and Spain where the ?Nota de Servicio de la Dirección General de Carretesas? is used. Structural topics of the approach slab are those less studied in actual practice. This is the reason we begun one structural study of the bridge approach slabs in the year 2000, including the soil-slab interaction. In the first period we have implemented the real traffic loads, the cracking of the slab and several support conditions to the structural model. We have realized the leading role of the fatigue phenomena on the real behaviour. Now and thanks to the investigation support of the Ministerio de Fomento we are making a much more accurate quantification on the main results of the first study. Actual job includes the improvement of the model mainly in the interaction of the slab and the embankment settlement, the analysis of the results of one inquiry on real bridge transition and laboratory tests of concrete slabs submitted to cyclic loads. Finally the model will be adjusted thanks to these experimental and real data. In the next pages we comment the results in the actual state of the work that includes improvement of the model and the analysis of the inquiry data.