Evaluation of the pull‐out test to determine the residual prestressing in concrete bridges.

In the context of existing post‐tensioned concrete bridges, a reliable assessment of load carrying capacity is still a challenging issue. The effective concrete compressive strength is related to the degradation process of post‐tensioned cables which cannot be detected by visual inspection only. Currently, in‐situ test methods combined with destructive techniques have been used as common methodology to assess either the concrete compressive strength and post‐tension cables losses. Yet, in‐situ tests are indirect approaches, and can be affected by several uncontrolled factors, playing a misleading role in strength determination. In this perspective, the paper aims to firstly introduce a theoretical background of pull‐out tests with their developments and limitations. Then, configuration test has been discussed to obtain reliable strength relationship, with emphasis on post‐installed inserts for pull‐out test. The main current standard provisions have been compared. This study intends to set the basis to test existing post‐tensioned concrete bridges with modified pull‐out test, having no effects on the structural integrity.