Hydraulic structures are gaining significant attention in the sustainable electricity market globally. The durability design of various elements of hydropower plants is a recently established engineering field, now recognized as essential during the design phase. The primary objective of the durability design is to ensure that the designated service life is met. Performance-based durability design refines this process by calibrating numerical simulations to predict the degradation of reinforced concrete or steel liners.
Hydraulic structures currently in the design stage are placing a strong emphasis on the durability of its various elements, targeting a service life of 150 years, which exceeds the provisions of existing standards. Current standards such as Eurocode 2, AS3600 and AS5100 typically specify concrete durability for up to 100 years. Beyond this period, the performance of reinforced concrete structures and steel liners must be assessed through numerical modeling. This modeling should be calibrated through laboratory tests and subsequent field tests, based on the actual concrete mix used during the design phase.
Some hydraulic structures are subject to unique daily transient loads that differ significantly from those experienced by conventional hydropower plants. These specific features result in exceptional degradation of massive reinforced concrete, not typically seen in traditional hydropower plants. Therefore, the durability assessment of these elements requires different considerations compared to standard practices in hydropower plant construction.
This study presents a comprehensive durability assessment plan for various elements of a large-scale project. The plan includes individual ad-hoc durability assessments for each element, taking into account all exceptional environmental exposure conditions, materials, and numerous calibration laboratory tests. For each element, after conducting a detailed survey of probable degradations and considering the unique loading conditions of the hydraulic structures, numerical simulations were developed to assess the impact of degradations on engineering parameters. Carbonation attack, freeze-thaw attack, corrosion of steel liners, corrosion of reinforcement in cracked concrete linings, and corrosion of steel components partially embedded in concrete were numerically simulated. The consequences of these degradations were then translated into engineering parameters used during the design phase.