Example Using Circular References to Force Iteration: Calculation Effective Section Modulus for Coldformed C-Section to AS4600



Calculation of effective section modulus (Zex) using effective width methods of AS4600, for a coldformed c-section. The workbook is dependent on: schTechLib It uses circular references to force iteration on the calculation of the section centroid. The web has a stress gradient and so the portion which is in compression and not effective is unknown. Has chunks are removed to determine effective width of plates, the section modulus of the c-section changes and so does the location of the neutral axis, and so the portion of the web in compression is different than initially assumed. The circular references force iteration until the difference between the initial assumption and the calculated value is insiginificant.

Calculation Reference
Cold Form Sections
Structural Analysis
Section Properties

Calculation Preview

Submitted On:
29 Aug 2010
File Size:
79.00 Kb
File Version:
File Author:
Conrad Harrison

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Comments: 1
InfoJunkie65 12 years ago
This method was my first approach for the effective width method, which I originally setup in Quattro Pro, it was one reason to move over to Excel and VBA. If look at schTechLIB, then will find VBA routines which directly calculate Zex and return to the worksheet cells. Example of using these functions in in the AS4600 calculator which is uploaded. Just use the calculator as basis of formatting a more presentable report. I tend to use Excel type calculators and use a pencil and write results on graphics (moment diagrams print from frame analysis software), keep reports compact: I have to do the photocopying.
For anything other than C-sections, I use CFS software (which does not fully support AS4600, I use becasue AISI:1996 and AS4600:1996 were aligned).
I would like to calculate warping constants and effective section properties for other sections. But not presently sure how to make my c-section routines entirely general. Also I tried working through the Duragal manual and had problems setting up iteration in a spreadsheet and could not get it to converge for a coldformed Angle.
So any feedback to help develop more general thinwalled , and coldformed section property calculator would be helpful.