Articles

An Innovative Solution for External Post-Tensioning Anchorages Using UHPFRC

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Abstract

This is an accepted article with a DOI pre-assigned that is not yet published.

Freyssinet Australia have designed, developed, and tested an innovative solution for the fixing of additional post-tensioning (PT) tendons to existing bridges. The solution involves precast anchorage blisters comprised of ultra-high-performance fibre-reinforced concrete (UHPFRC)—a first in Australia. The selection of UHPFRC over more common construction materials such as reinforced concrete or steel allows for a significant reduction in the blister size and weight. Unlike currently available external PT systems, the UHPFRC blisters are intended for use with medium to large multistrand PT systems and are therefore particularly well suited to the strengthening of existing medium to large-span concrete bridges. Current strengthening methods generally require installation of many single strand or smaller multistrand PT tendons. These systems require considerable preparation of the existing structure including coring a substantial number of new holes to attach the new PT and can become widespread over the structure's surfaces. This causes these systems to become unsightly and subsequently undesirable to asset owners. Alternatives include large in-situ anchorages; however, these elements can add significant dead load to the structure and are difficult to blend into a bridge's aesthetic. The development of a PT anchorage that reduces the coring required for installation represents a significant advancement in the field of bridge strengthening. The minimalistic nature of the blisters also ensures that they provide a highly sustainable solution to growing infrastructure needs and that works undertaken on infrastructure within urban environments are less likely to affect public perception, both game-changers in the approvals process.

Keywords: external post-tensioning, anchorages, UHPFRC

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