An arch dam transfers loads to the abutments and foundations both by cantilever action and through horizontal arches, and a method of distribution was developed by Stucky in Switzerland and the USBoR.

The assumptions made are not strictly true so the effect of each must be understood before accepting the design.

The parameters controlling design, other than actual geometry include:

Steel reinforcement can reduce the thickness of the dam but at a cost. If reinforcement was not used then cracking in the faces of an arch dam may result from:

Definition of different arch dams based on base thickness (h is height of the dam):

Thin arch<0.2h
Medium arch0.2h - 0.3h
Thick arch>0.3h

Reinforcement is not generally required in arch-gravity dams or thick arch dams. Its use in thin arch dams is favoured, however for a 90m high dam the cost of reinforcement will be many millions of dollars, which could mitigate the adoption of such a dam.

Uplift - is not usually of importance in thin arch dams, but in thick arch dams provision is made for internal drainage, as for gravity dams. If the design assumes that the concrete will crack if tensions exceed say 0.4MPa, then it is consistent to assume that full hydrostatic pressure can act in such cracks.

Tensile stresses - the aim of the designer is to eliminate tensile stresses, although this is not always possible since an irregular cross-section can generate local stress concentrations, and necessary excavation of abutments beyond the design limits will alter the geometry of the dam, and possibly affect the degree of fixity.