Innovative Strengthening Technique Using Post-Tensioned Fibre Composite Wraps for Bridge Headstocks

Abstract

SummaryEngineered fibre composites offer an extremely versatile option to strengthen existing structures to solve structural problems arising from environmental exposure, inadequate designs, increased traffic loads and continuous aging of existing structures. While the behaviour of structures by external post-tensioning using fibre composites for flexure is well understood, there is limited research on shear strengthening, specifically using pre-stressed fibre composites. An innovative system using fibre composites has been investigated for strengthening bridge headstocks with deficient structural performance. The innovative system uses fibre composite wraps that forms an infinite loop around the headstocks and together with anchorage blocks, these are pushed-out and the gap packed with a suitable spacer to maintain the applied pre-stressing force. This paper discusses the research, development and construction of this innovative fibre composite post-tensioning system, and testing it on a model bridge headstocks in Tenthill Creek Bridge. Issues related to the effect of existing shear cracks and the importance of repairing such cracks will be discussed. With further investigation, this strengthening system could be implemented in actual structures to enhance the capacity of bridge headstocks.