Sample Spreadsheet Calculations for Portal Frame Shed

Example spreadsheet calculations for determination of wind loads on a building with  a doubly pitched roof to the criteria of AS1170.2. Once reference wind pressure been found, then pressure coefficients on the external surfaces are found for directions theta=0 (transverse wind load) and theta=90 (longitudinal wind load). The moments in an assumed single span doubly pitched portal frame (or gable frame), are then calculated using Kleinlogel rigid frame formula: the frame is assumed to have fixed bases (eg. moment connections). Then based solely on sectional strength a minimum size steel section is selected. This section may not be suitable if cannot provide adequate lateral torsional restraint, and pass the detailed member capacity checks.

These calculations can be carried out using the following spreadsheet:

schShedDesignerR01.xls

Additional structural calculations are required to design a full building, this is just the calculations for the action-effects of the primary frame, and the design actions on the building. Ignoring the rigid frame, the spreadsheet simply provides the wind actions for the surfaces of the building which can be used to assess/design other components. Other components would include the following:

1. Roof X-Bracing and struts
2. Wall X-Bracing and struts
3. Roof Purlins (cladding rails)
4. Wall Girts (cladding rails)
5. End Wall Mullions

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schShedDesignerR01 by Conrad Harrison

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Revisions:

[08/06/2014] : Original
[14/09/2015] : Added some notes.

Technical Function Library

This is a library of functions for calculations to various Australian structural standards including:

1. AS1170.2 Wind loading 
2. AS4100 Steel structures code 
3. AS4600 Cold-formed steel structures code 
4. AS1720 Timber structures code 

It also contains a lot of experimental litter. It is an absolute necessity for using all my other spreadsheets. Spreadsheets are useful, but I find vba code more reliable and easier to read when it come to conditional tests, branching, and looping. Spreadsheets are not very reliable when it comes to tabulated calculations nor efficient. In a database management system an equation is defined once for a group of records and then progressively executed on each record. In a spreadsheet the equations have to be defined for each and every record (row) of the spreadsheet and that leads to potential error. It is also easier to expend an array in vba than it is to add extra rows to tables and mesh several tables together. Even if using tables of calculations in a spreadsheet it is easier to call vba functions to achieve greater consistency for each cell calculated, and too hide lots of complex conditional tests behind the scenes. Each different audience and purpose for calculations requires a different presentation, having vba functions provides greater flexibility compared to merely replicating hand written calcs in a worksheet.

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Taken from the ExcelCalcs.com website.