Background to CS 455: The assessment of concrete highway bridges and structures

The UK Design Manual for Roads and Bridges (DMRB) document CS 455 for the assessment of concrete highway bridges and structures has been rewritten and updated as part of the project to update the DMRB suite of documents. The key technical changes introduced in the document are outlined in this paper, including: methods for estimating worst credible strength; simplification and improvement in shear resistance near a support where there is a short anchorage length; incorporation of strut-and-tie modelling; serviceability limit state assessment requirements for prestressed concrete; shear resistance of prestressed concrete; and new rules for the effect of cover on bond. The technical background to the key changes is briefly outlined and some of the efficiencies that can be delivered using the new document are highlighted.