Modification of traditional supporting steelwork system for non-standard structures

•Traditional SSS is usually used for patch repairs of standard structures.•TE truss of traditional SSS is modified for a non-standard structure.•The suggested hanging arrangement in existing TE truss was analyzed in LUSAS.•Only vertical members of existing TE truss were needed to be upgraded.•Cost analysis revealed that the modified SSS was an economical solution.

This paper explains a concrete repair project at Midland Links Motorway bridges in West Midlands UK in which a novel modification technique was adopted and discusses the applicability of same approach to other highway structures around the world. The modification to the traditional supporting steelwork system (SSS) required for carrying out concrete repairs to a deteriorated non-standard structure is made. The non-standard structure of Midland Links under study was a viaduct passing over a river (i.e. waterway). Traditional SSS was not possible to use because the trestle arrangement could not be placed in waterway. Therefore, trestles need to be avoided which leads to introduction of a hanging system. For this, existing Type E truss of the traditional SSS was modified to incorporate hanging arrangement (hangers and needle beams) instead of fabrication of new SSS. This modified SSS was analyzed using the finite element software LUSAS. The section capacities of the truss members were assessed under the applied loading and over-stressed members were satisfied by using enlarged sections. Finally, cost analysis for new and modified SSS was carried out. It was found that the later option was an economical solution compared to the earlier one.