Investigation, assessment, strategy for deck widening of existing HWY PT bridges

Autostrade per l'Italia (ASPI) is planning the upgrading of several highway axis for approx. 150 km in the next years. Most of the original bridges, built around ‘60/‘70, have already been widened in the 90s but should now be widened again. The original decks are often made of a grid of post‐tensioned elements, while the further enlargements were built with different solutions (precast pre‐stressed beams or steel beams).

To assess the material properties and the internal conditions of the post‐tensioned decks, several investigations with non‐destructive and semi‐destructive testing have been carried out, in accordance with Italian Guidelines.

This paper illustrates the main results collected, also highlighting the difficulties encountered to achieve a sufficient understanding of the degradation conditions. The assessment process evidenced that for a large part of the post‐tensioned decks it was more convenient to intervene with the replacement of the existing decks rather than rehabilitate them. The main reasons supporting this choice are explained.