STRESS ANALYSIS IN CONCRETE OVER THE DRAFT TUBE IN A POWER HOUSE BY FINITE ELEMENT METHOD

Abstract

The hydel power station from structural viewpoint is divided into 3 divisions namely substructure, intermediate structure and superstructure. These parts also have different hydraulic and structural functions. The present study is concerned with substructure only. Substructure is a massive concrete structure containing draft tube cavity. It performs the function of distributing loads to the foundation. It being the lowest part of power house supports all the loads coming from intermediate structure and superstructure lying above it. This study deals with a surface power station with vertical setting reaction turbine having elbow type draft tube. The substructure, which extends from the top of draft tube roof to the foundation, contains hollow spaces and cavities of complex shapes. The main cavity is calleddraft tube and functions as water passage for exit of water. Other cavities are for inspection and drainage. In addition to these it may contain galleries for installation of measuring instruments. So the substructure is not a solid structure. Moreover all the loads transferred from intermediate and superstructure act on top of it. These loads are generally of following types. i) Loads including plant & equipment ii) Forces induced by water iii) Uplift forces iv) Wind loads v) Earth Pressure vi) Crane load vii) Seismic forces viii) . Any other load specific to location....