May Technical
VertGate
This Vertical Lift Gate Design program provides a comprehensive design analysis for vertical lift gates with the minimum amount of effort. The program encompasses many different design options and provides a conservative design. Microsoft Excel workbook is used so that operation is both familiar and easy. Visual Basic macros are used throughout to facilitate design.
Design
The vertical leaf gate assembly comprises a number of horizontal girders welded to end members designed to transfer hydrostatic and seismic loads to embedded guides. The skinplate is considered to be an integral part of the girders with the whole assembly being stiffened vertically by diaphragms as necessary.
The spacing of the girders on the gate is optimized by the program, or, may be entered manually. The size of the girders may be user entered, or, selected from a built-in AISC database of standard beam shapes and sizes.
Hydrostatic and seismic loads are considered in the design. Seismic loads act on the gate during an operational basis earthquake (OBE) resulting in horizontal acceleration. The Westergaard formula is used to determine the added water pressure on the gate.
Allowable strength design methods are used per AISC Manual of Steel Construction - 13th edition. For normal loading conditions, the allowable strengths are multiplied by a user definable design factor based upon recommendations from the Corp of Engineers EM 1110-2-2105. Also reference EM 1110-2-2701.
The spacing of the girders on the gate is optimized by the program, or, may be entered manually. The size of the girders may be user entered, or, selected from a built-in AISC database of standard beam shapes and sizes.
Hydrostatic and seismic loads are considered in the design. Seismic loads act on the gate during an operational basis earthquake (OBE) resulting in horizontal acceleration. The Westergaard formula is used to determine the added water pressure on the gate.
Allowable strength design methods are used per AISC Manual of Steel Construction - 13th edition. For normal loading conditions, the allowable strengths are multiplied by a user definable design factor based upon recommendations from the Corp of Engineers EM 1110-2-2105. Also reference EM 1110-2-2701.
For fixed-wheel gates the roller assemblies are also designed using the program. Crowned rollers and their axles are fully designed in accordance with criteria outlined by Skinner's "Fixed-Wheel Gates for Penstock Intakes". The design of rollers, bearings, axles and their supports take into consideration the lateral load acting on the roller due to possible roller misalignment. Wheel axles may be cantilevered from the end of the gate or supported at each side of the wheel by vertical end members.
Results
Beam section properties are calculated based upon the information provided. These properties are determined in accordance with AISC. The nominal strengths are calculated and take into consideration compression and tension flange yielding, lateral torsional buckling and compression flange local buckling. Stresses are determined and compared to allowable stresses in general accordance with AISC requirements. All significant calculated results are highlighted in green where acceptable and red where not acceptable.
Operation
Side, lintel and sill seals are designed including frictional loads that affect gate operation. Gate operating loads are determined from gate volume, weight and center of gravity based on the dimensional data provided. The downpull on a vertical lift gate is also considered with the gate at partial openings. Downpull applies to a submerged fixed-wheel gate with a downstream lintel seal and downstream skinplate under flow conditions. Calculation of downpull is per "Hydrodynamic Forces" by Naudascher. Hoisting loads are calculated for a range of gate positions both for gate lifting and lowering.
Changes for 2022
The program has been modified for 2022, primarily to include the option for metric units. As part of this change there is a new "Parameters" worksheet which provides a single entry point for most parameters that are critical to the design. Upon entry of each parameter on this sheet, the subsequent worksheets are automatically updated. A "CHECK" button is provided on this worksheet which enables the user to check input values and major aspects of the design, making sure the entered parameters are sensible and workable. These checks do not override the design and are simply checks. A "Dimensions" worksheet is added to show the resulting design as drawings. A cross-section of the top and bottom beams is shown with a scroll button for intermediate beams. These drawings are indicative only since the actual design details will vary. Each worksheet now includes more detailed descriptions to obviate the need for a separate user manual.