Estudio experimental y numérico del comportamiento de puentes prefabricados monoviga bajo cargas de servicio

Experimental and numerical study of the behaviour of precast concrete box girder bridges under service load conditions

Sequential construction is frequently used for mid-span concrete bridges, such as those composed by precast prestressed beams con-nected to a cast in place reinforced concrete top slab. Such kind of bridge decks have evolutioned considerably with the use of bath tub beams monolithically connected by means of longitudinal prestressing. resulting in a very competitive solution because of their structural performance, aesthetic appearance, assembly velocity and global economv. However. the use of different materials in a same section. the evolutionary construction in both longitudinal and transverse directions and the effects of creep, shrinkage and relaxation of prestressing steel lied to complex stress and strain states and even to induced cracking. Such effects can modify the structure response, making it difficult to predict deflections. stresses and strains in order to verify the serviceability limits states. For this reason a 1:2 scale model of a sequentially erected continuous precast box girder bridge has been tested under service load conditions. The experimental results have been compared with those numerically predicted using de F.E. Method. Conclusions are drawn about the real stress and strain distributions, emphasising on the effects of the sequential construction on the shear lag phenomenon, and on the general response of the structure.