3-D FINITE ELEMENT ANALYSIS OF A BARRAGE

Abstract

The objective of this dissertation is to study static and dynamic behavior of a barrage consisting of five bays under varying foundation conditions using finite element method and to study the behavior of raft, piers and abutments under worst case of loading. The Finite Element package, ANSYS has been used to carry out the various analyses. The barrage is located partly on soil and partly on rock. The barrage has been analyzed considering a total of nine models. Three composite models are considered to study the behavior of raft, four standalone models are considered to study the behavior of piers and abutments and two hyper composite models to study the structure-structure interaction under seismic excitation. The Barrage has been modeled using 2D Plane42 elements (4 noded quadrilateral elements) and 3D Solid45 elements (8 noded brick elements). Relevant amount of soil around the Barrage has also been modeled to find out the effect of soil on the structure. Static analysis of the Barrage has been carried out considering dead loads (self weight of structure, gate loads), uplift forces and hydro static forces. Free vibration analysis has been carried out to find out the natural frequencies and mode shapes considering stiffness of the soil and mass and stiffness of the structure. Seismic analysis of the Barrage has been carried out using the response spectra of the site by giving excitation in transverse direction. The study indicates that the standalones are on conservative side for designing piers and abutments. Further, conventional methods of design should not be used for such type of site. A detailed finite element analysis is more realistic in these situations which takes into effect various parameters in the study of complex continuum, yielding design values where conventional techniques/ methods are incapable of providing a solution.