Stresses in Concrete Around Spiral Case

The concrete around the spiral case of a hydroelectric power station has such a complex shape that determination of actual stress distribution and explanation of its structural behavior is very difficult. This paper reports the results of original research work done on three-dimensional analysis of such a structure. Photoelastic technique has been employed to determine the six components of stress at 2,700 points due to the static generator load. The results are of far-reaching importance insofar as they reveal the structural behavior of spiral case concrete, which is entirely different from the prevalent design practices, based on elementary two-dimensional theories. The stress diagrams given and the structural behavior explained will help designers evolve safe and economical solutions to the problem.