Viaducto de hormigón de alta resistencia y pretretensado exterior: puente sobre la riera de Rajadell en el eje transversal de Cataluña

Externally prestressed high strength concrete viaduct: the bridge over Rajadell river on the transversal highway of Catalonia

The paper presents the most important issues regarding the design and construction of a threespan (40 + 51 + 40 m) continuous viaduct with high-strength concrete (60 MPa) and external prestressing. The description and reasoning of the final adopted solution involves the evolution of the cross-section from a standard box-girder to the final open section with two webs (only 30 cm wide each) connected by an upper slab. The problems found in the checking of the Serviceability and Ultimate Limit States due to the use of high-strength concrete combined with external prestressing are also commented. Two main topics are adressed in the paper. First, the response up to failure by bending of the bridge. The analysis and calculation of the actual safety factor is carried out using a non-linear Finite Element model specifically developed for bridges with exter-nal prestressing. The second point of interest is the cracking due to heat hydratation, which is very high in bridges with external prestressing due to the necessity of huge anchorage diaphragms with large dimensions, and the high cement content of concrete. During concrete curing, the real temperature distribution was measured in the bridge by thermocouples. Using the most unfavourable thermal distribution the auto-stress configuration in the abutment diaphragm is evaluated via a Finite Element model.