Design and Sensitivity Analysis of High Head Regulating Radial Gate Using Microsoft Excel Spread Sheet

Abstract

Gates and hoists based on different principles and mechanism are being used for particular discharge of water through spillways, sluices, intakes, regulators, ducts, tunnels, etc., as well as to facilitate planned and controlled reservoir operation and also for maintenance purposes. These structures manually operated, powered or automatic to restrict the flow of water on a need basis. Different types of gates have been developed/evolved over a long period of time from early wooden logs, caterpillar gates to the latest fixed wheel, slide gate and radial gate to control the design discharge of water via Canal, conduit or spillway. Crest-type radial gates have been constructed in very large sizes, with areas up to 560 m2, widths up to 56.5 m, and heights up to 22.5 m. Orifice type radial gates have been constructed with areas up to 114 m, widths up to 12.8 m, heights up to 9.5 m, and heads up to 135 m. [Design Guidelines For Spillway Gates: Chander K. Sehgal, Member, ASCE] For high head installation; radial gates, requiring lesser hoisting capacity and control are much more economical and beneficial than that of other gates. The paper covers the design of high head (i.e. more than 30 m head over sill) regulating (i.e. intended for maintaining particular discharge and not intended for maintenance purpose like stop log gate) radial gate beginning from the selection of material, determination of stresses up to size of its components viz. skin plate, stiffener, girders, arm, trunnion, trunnion pin and hub and its assembly/location of each components. Prevailing softwares like ANSYS applicable for finite element analysis and CATIA for 3D modelling are also being applied for gate design. However, these softwares are costly and require high technical skill and even exporting output (data) from these softwares to another file format may not be possible or much more complex. Unlike those prevailing softwares, Excel Spreadsheets provide complex processing in ways that even people with little technical experience can access. The appearance of every part of the spreadsheet lies under user total control. Therefore, a Microsoft Excel spreadsheet has been developed for the design of components with particular input. It will reduce the tedious calculations of several force analyses and errors in computing for designing. A sensitivity analysis is a useful tool or method to identify the impact of different values of an independent variable upon a particular dependent variable under a given set of assumptions. The paper also shows the graphical representation of the impact of the change in individual input parameter upon the gate design. For this, the same excel sheet has been used for the sensitive analysis with the change in input (variable) parameters, which is very essential during planning stage in the decision-making of suitable location, cost, fabrication, erection aspects of the radial gate.