For a high head gate with an upstream skin plate and a conventional sealing arrangement, the location of the horizontal girder is determined based on either equal load or equal reaction on each girder, without considering the deflection at the top of the skin plate. In the method proposed in this paper, the location of the horizontal girder is determined with due consideration to this equal reaction in order to provide a unique cross-section of all the girders, deflection of the top girder, and the possibility of the bottom girder flange being hit by the water jet of the hydraulic jump on the downstream side of the gate. For the upstream skin plate and upstream top rubber seal, the deflection of the top of the skin plate is restricted to 80% of the pre-compression of the rubber seal, and the allowable deflection of other horizontal girders are span/800, as per the Bureau of Indian Standards code IS:4622[4]. A formula for calculating the number of girders is also proposed, as the current procedure gives a higher value for the same thickness of skin plate. The proposed methods are described step-by-step for determining the number of horizontal girders, as well as their location.
