Marine pile design using steel tubular piles with concrete infill assumes a two-phase load transfer mechanism. Initially, the steel pile shoulders the load from the pier deck. However, as corrosion inevitably affects the portion of the pile above the seabed, the load distribution shifts. The concrete infill becomes the primary load bearer above the seabed, while below, friction between the infill and the remaining steel casing facilitates load transfer to the deeper sections of the pile.
A critical challenge arises due to the concrete’s tendency to shrink and contract after it’s cast within the steel pile. This shrinkage can disrupt the bond between the two materials, potentially compromising the reliance on friction for load transfer. To mitigate this issue, engineers have two primary solutions:
- Shear Keys: Strategically placed shear keys within the steel pile create a mechanical interlock with the concrete infill. This ensures a robust connection and efficient load transfer even when shrinkage occurs.
- Expanding Agents: Incorporating expanding agents into the concrete mix counteracts shrinkage, maintaining close contact between the concrete and steel. This preserves the frictional interface necessary for effective load transfer below the seabed.
By implementing these measures, engineers can address the potential pitfalls of concrete shrinkage and ensure the structural integrity and longevity of marine piles in corrosive environments.