Assessment of Tame Valley Viaduct

Tame Valley Viaduct is a key link within the West Midlands highway network. Earlier assessments had indicated that the viaduct was inadequate for current loading. This paper describes the detailed assessment undertaken to improve the capacity rating, aid the interim management of the structure and minimise subsequent strengthening requirements. The steel-composite box-girder construction is extensively stiffened with bulb-flat stiffeners. Standards suggested that these were susceptible to torsional buckling. Studies using non-linear finite-element models were able to demonstrate the adequacy of the web stiffeners, thereby allowing the associated web panels to be used at their maximum efficiency. Similar modelling demonstrated that non-standard longitudinal stiffeners could develop adequate post-buckling capacity to be used in the Eurocode effective-area method of calculating the resistance of plated structures. The comprehensive approach assessed each and every panel of the box girders, rather than conservatively selecting critical panels. This required creation of a structural information model and a bespoke software tool to automate the assessment process.