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Prestressing of bridges allows construction of long spanned bridges made from thin structural members with high flexural and shear capacity. Studies have shown that some of the existing prestressed bridges are not meeting their designed service life due to corrosion of the tendons. The main reasons are poor construction practices in combination with inadequate inspection and maintenance plans. This paper provides a summary of repair options for corrosion-damaged prestressed concrete structures with focus on the individual components of the prestressed system. The applicability of identified repair options to Norwegian conditions is discussed.

Within the Norwegian Public Roads Administration, the use sensors of durability monitoring (potentials, corrosion rates, resistivity etc.) was first investigated during a research project on a North Norwegian bridge in the beginning of the 1990s. The knowledge earned from this initial test has been used to compile national recommendations shortly after. Still, durability sensors are seldom used on bridges in Norway today, apart from systems for cathodic protection where potential measurements are frequently executed. During the 1990s to 2020s, durability monitoring was several times applied in research projects and results show how sensors effectively can be used to assess corrosion and durability in concrete elements. To promote the use of durability sensors, the Norwegian Concrete Repair Association newly published a guideline on how to use, install and analyze durability monitoring systems. The paper summarized experience with the use of sensors for durability monitoring on Norwegian bridges and research projects. Today, there is an increasing demand for solutions allowing the automated monitoring for bridge safety and durability. The status and possible further applications of durability sensors on Norwegian bridges are briefly discussed at the end of the paper. [ABSTRACT FROM AUTHOR]

Corrosion of posttensioned bridges raises great concern, since the only way to safely assess the condition of the tendons is through destructive evaluation. In this scenario, this paper presents the results of an extensive literature review on reported cases of corrosion of posttensioned bridges and few prestressed structures. The aim is to increase knowledge about the structural consequences of possible corrosion‐induced failure mechanisms. The cases were rated according to the increasing severity of the observed damage and consequent interventions as follows: ordinary maintenance is effective, extraordinary maintenance is necessary, and maintenance is insufficient or absent. It was found that most corrosion‐sensitive structures were segmental and box section beam bridges. Most cases required extraordinary maintenance. Warning signs were often observed. The damage was mainly ascribed to design and execution mistakes that facilitated the ingress of external chlorides causing corrosion. The paper concludes with a discussion of the consequences for structural safety. [ABSTRACT FROM AUTHOR]

This study was based on findings from the Norwegian Public Roads Administration's Bridge Management System and field investigations on corrosion damage in pretensioned Norwegian standard I‐beam (NIB) girders in 227 coastal climate bridges. The main durability design parameters are summarized and related to regulations over the last 80 years. Environmental exposure is discussed in the light of the global, local, and micro climate. We found that 51% of the bridges have girder corrosion damage. The percentage is highest for bridges built when the cover thickness required was lowest. Cover thickness below that required (resulting from production faults) caused 74% of corrosion damage. Most of the severe chloride‐induced corrosion damage in bridges was found in the inner NIB girders, particularly in the support‐zones and their vicinity. This can be due to interaction between geometry and exposure. Corrosion of reinforcement in support‐zones can impact structural behavior, particularly NIB girder shear performance. [ABSTRACT FROM AUTHOR]