Composite twin-girder bridges: A competitive solution for medium span bridges

Ever since the eighties, composite bridges have found a field of application in Spain in the upper range of medium span bridges and have served as a serious alternative to more traditional prestressed concrete solutions. Their progressive introduction in this area Is perhaps due to the lack of the auxiliary resources required for the construction of these spans In concrete, such as self-launching falsework and perhaps on account that other construction techniques such as advance cantilever construction tend to be excessively expensive outside their optimum range of application. However, in spite of the advantages they offer, composite solutions have not yet found a clear application in the lower range of medium spans. Perhaps the excessive use of box-girder type systems as opposed to other simpler and more competitive options has prevented composite bridges from being considered as a true alternative in this range of constructions in prestressed concrete, as occurs in other countries in our vicinity. One of the types that complies with these requirements is the twin-girder bridge which predominates among the composite solutions employed in Europe, but which, in spite of its irrefutable advantages, has only been employed on a limited number of occasions in Spain.