The generator foundation of Hydro-turbines are subjected to static loads such as self weight of the generator and rotor assembly, dead and live loads of the generator floor, and dynamic loads, for instance tangential loads on stator, rotor pedestals/sole plates, short circuit and radial forces on rotor sole plates. The foundation of barrel starts from the mass concrete embedding spiral casing and draft tube underneath. The generator barrel wall also acts as support for the generator floor. The stresses developed in barrel concrete and deformations are three dimensional. In absence of exact design procedures approximate methods are adopted. Mosonyi (1960) suggested the design of the structure to be done considering direct stress and torsional stress due to torque. An approximate beam-column theory is proposed for the design of the foundation. Nigam (1985) presented a typical design of a barrel foundation of a 60 MW hydro-generator by an approximate method of the column-beam considerations. He computed normal stresses at the foundation level of the barrel subjected to static generator loads, and shear stresses considering torques due to radial and tangential forces. In this paper stresses and deformation of a similar barrel type generator foundation are analyzed and computed by Finite Element Method (FEM) using ANSYS CAE software in conjunction with 3D CAD solid geometry which would facilitate economical and safe design. A comparative study is done between the conventional analysis by Nigam and the present study through FEM. Considering static and dynamic loads equivalent stresses and expected deformations are computed at various locations in concrete of barrel foundation. The result shows that maximum stresses occurrs towards the center of the barrel.

Keywords: Hydel-power house, Barrel foundation, Stresses, Deformation, FEM.