Structural Analysis of The Bifurcations at Phukot Karnali Hydropower Project

Abstract

The research is based on the structural analysis of bifurcations located in the intake manifold of Phukot Karnali Hydropower Project. The analysis is done with Finite Element Approach (FEM) Approach by making use of Ansys Mechanical 2020 R1. The geometry of the bifurcation is based on the original design data and recommended dimensions including bifurcation angle, cone length and pipe thickness from previous research on the same hydropower project. From literatures it is found that the suggested thickness of the pipe is 130 mm for the first bifurcation and 70 mm for the second bifurcation by conducting structural simulation of the pipe without adding any structural elements. At the actual hydropower site however, the bifurcation is covered in concrete. Firstly, structural analysis is conducted on the two bifurcations by adding ring reinforcements around the inlet and outlet pipes. The maximum value of resulting stresses on the two models found to either be borne by the rings or the maximum displacement seen is observed on the joints of the reinforcements. Therefore, the models for the analysis with concrete blocks are simplified. From the results of the analysis the observed value of maximum stress on the concrete is much lower then the allowable value, the process is repeated with thinner (reduced by 10mm in each model) pipes to assess the rate of changing stress values.