Structures such as dams, bridges, towers etc., require structural strengthening when they lose their capacity to serve the designed purpose. This shall happen to any new or old structure.
In old structures the cause may be due to disintegration of raw materials/elements, environmental impacts or combination of both in varying degrees. These defective segments need to be replaced with proprietary repair systems on the approval of the structural engineer. If there are any requirements to improve the serviceability condition it is needed to add additional / enlarge structural components to match to the designed values of the structural engineer.
In the case of faulty construction, the remedial method shall be complex and time-consuming since there is no code of practice of how to build a defective structure.