Industry design and construction standards (American Concrete Institute [ACI], American Association of State Highway and Transportation Officials [AASHTO], etc.) are adopted as applicable to provide safe, reliable, and cost effective hydraulic structures for civil works projects.

Reinforced Concrete Hydraulic Structures (RCHS) are directly subjected to submergence, wave action, spray, icing or other severe climatic conditions, and sometimes to a chemically contaminated atmosphere. Satisfactory long-term service requires that the saturated concrete be highly resistant to deterioration due to daily or seasonal weather cycles and tidal fluctuations at coastal sites.

The often relatively massive members of RCHS must have adequate density and impermeability, and must sustain minimal cracking for control of leakage and for control of corrosion of the reinforcement. Most RCHS are lightly reinforced structures (reinforcement ratios less than 1%) composed of thick walls and slabs that have limited ductility compared to the fully ductile behavior of reinforced concrete buildings (in which reinforcement ratios are typically 1% or greater).

Typical RCHS are: stilling basin slabs and walls; concrete lined channels; submerged features of powerhouses and pump stations; spillway piers; spray and training walls; floodwalls; submerged features of intake and outlet structures (towers, conduits and culverts); lock walls; guide and guard walls; and submerged retaining walls and other structures used for flood barriers, conveying or storing water, generating hydropower, water borne transportation, and for restoring the ecosystem.

This manual describes typical loads for the design of RCHS. Load factors are provided. The load factors resemble those shown in ACI 318, but are modified to account for the serviceability needs of hydraulic structures and the higher reliability needed for critical structures.

RCHS typically have very long service lives. A service life of 100 years is the basis for the requirements of this manual. RCHS shall be designed with the strength design method in accordance with the ACI Standard and Report 318-14, Building Code Requirements for Structural Concrete and Commentary (ACI 318), except as specified hereinafter.

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