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|Title:||A COMPARATIVE STUDY OF ANALYTICAL METHODS FOR RAFT FOUNDATION OF A BARRAGE|
|Authors:||Kulkarni, Moushami D.|
|Abstract:||The objective of this dissertation is to have a comparison of methods of analysis of raft foundation of a barrage especially of two methods viz., Hetenyi's method and Finite Element Method. The Mahanadi barrage considered for study has 96 bays out of which the raft floor of the left undersluices bays 1,2 and 3 has been taken up for analysis and has been modeled by 3D 8 noded brick type of element using the ANSYS package for Finite Element. Analysis. Two aspects have been looked upon for comparison, one with respect to Raft analysis and other being with respect to Pier analysis. In the Pier analysis the effect, of a load applied at the pier top, on the raft has been studied by applying unit loads at different points along the raft. The reactions acting along the base of pier were calculated for each individual load and its percentage distribution on the raft was plotted (Graph no.19 to 34). It was observed that the conventional practice of conversion of a point load applied on a pier to an equivalent uniformly distributed load considering a dispersion angle of 450 is in error as the actual load are localized and hence have a much higher magnitude. Further it was significant that the pier raft interaction cannot be studied using this concept, which considers the raft as a 2 D entity. 111 In the Raft analysis, moments at different points along the raft of barrage have been calculated by Hetenyi's method and FEM and their comparison has been done for typical cases considering flow and no flow conditions incorporating earthquake loads. From the analysis it was observed that the general concept that Hetenyi's method is conservative is not necessarily true. Further it was observed that in barrages where there exists a pier at the raft end the moment estimated by Hetenyi's method at the end of raft is incorrect and hence in such barrages Hetenyi's method is not appropriate. Also, since the raft as a 3 D entity is not accounted for in the Hetenyi's method, the clause of IS 11130-1984 recommending Hetenyi's method for analysis of raft under barrages demands necessary rectification. The observations from the raft and pier analysis indicated that Hetenyi's method may be done for the preliminary dimensioning of the raft but the final design should be done by using. Finite Element Method.|
|Appears in Collections:||MASTERS' DISSERTATIONS (Earthquake Engg)|
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