What methods for reinforcement of marine structures exist?
There may be many reasons and causes for upgrading an existing structure, with the following standing out:
- Change of use or overloading of design
- The restoration of the original structural response after a loss of resistance capacity has occurred (durability, explosions, accidents)
- Resolving defects in the execution of the project
- Modifications to the original structure
- Loss of strength in reinforcement
As a general rule, reinforcement actions must be considered when it is necessary to increase the resistance of one or several structural elements to extend the useful life of the repaired structure.
The reinforcement of the structure can be either passive or active:
As a whole, these types of structural strengthening are embodied in one of the actions listed in EN 1504-9, which specifies the “Principles and Methods for the Protection and Repair of Concrete Structures – Principle 4: Structural Strengthening. Increasing or restoring the structural load bearing capacity of an element of the concrete structure.”:
In practice, the three structural reinforcement actions shown in the following table are the most commonly applied in the marine environment:
To conclude, it must be mentioned that the use of structural steel for upgrade actions in structures in marine environments poses several challenges.
The main problem with the use of structural steel as reinforcement is the high aggressiveness of this environment for steel, which is why it is necessary to provide protection to guarantee its durability since this environment for steel causes rapid corrosion.
In a saline atmosphere, self-skidding steels, resistant to atmospheric corrosion by autooxidation, do not develop the mechanism of self-protection, so they are not valid.
Meanwhile, stainless steel is an expensive option, which is generally justified only when it cannot be protected or maintained.
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