Prestressed concrete box girders with web tendons and unboned transverse prestressing

With the introduction of regulations and guidelines for the design of civil engineering structures (BEM-Ing) especially for the calculation and design of concrete bridges (part 1, section 2), road bridge construction using prestressed concrete will change. For the first time since 1999 the arrangement of internal tendons in webs of box girders, it is permitted again. However, in order to avoid the shortcomings observed in some road bridges, which result, among other things, from a insufficient compaction of the concrete in the webs, stricter boundary conditions for the use of the bridge tendons in road bridge construction will be anchored in the future, while their possible applications in railway bridge construction will remain unchanged. In addition, it is strongly recommended to design road slabs of large width with transverse prestressing. For the deflection limitation of transversely prestressed road slabs, the maximum prestress force is limited in BEM-Ing, which can be used to determine the required plate thickness by controlling of the concrete tension stresses. This article provides hints on the design and construction of prestressed concrete box bridges according to the new BEM-Ing and shows which component dimensions result from the new rules.