The TrashRack program provides an analysis of typical trashrack panels and their supports. Trashrack panels comprise rows of parallel bars spaced to minimize flow interruption while preventing debris from passing downstream. The bars are laterally braced to prevent vibration and improve stability.
The bars are designed for bending strength which depends upon the spacing of the horizontal beam supports. The bars are vertically oriented to enable raking.
The program assumes rectangular bars are used since it is cost prohibitive to fabricate steel bars of a more streamlined shape. Plastic bars may be used, however, the manufacturer should be consulted in that case. If trashracks are installed in cold climates then the potential for freezing should be considered (not part of this program).
Reference should be made to "Recommendations for Design of Trashracks for Intakes" IS 11388 for more detail.
The program considers the following:
- A variable number of horizontal supports
- Optimization of support spacing
- Use of tie-rod spacers or welded bar spacers
- Design for 100% blockage or a failure differential head
- Fixity at lintel and sill may be specified
- Calculation of moments and reactions for the trashrack bars
- Selection of standard beam sections for the intermediate supports with use of I-shapes, channels or rectangular tubes
- Structural design according to AISC 360
- Calculation of vortex shedding with natural and forcing frequencies
- Vibration safety check
- Determination of head loss using Rihand or Kirschmer
- Determination of trashrack panel weights
- Use of imperial or metric units
Microsoft Excel workbook is used so that operation is both familiar and easy. Visual Basic macros are used throughout to facilitate design. Caution and good engineering knowledge should be used in the selection of parameters as well as the interpretation of the results.