Daily Challenge Day 57

So its 23:20, and not really in mood for writing.

I created a new spreadsheet for calculating wind loads on purlins, as described yesterday. When I set it up, I presented the calculations in simple vertical format from theta=0 to theta=90, my intention was to stick with my standard two column format: that is divide the page into two columns the left column used for theta=0, and the right column used for theta=90. So I started out by compressing everything to the left column before dividing the page and then dragging all the theta=90 calculations to right side of page. though whilst I was doing the compressing I had the idea of presenting the calculations for kl=1.5 on the left and kl=2 on the right. Such presentation has its usage, but didn’t go down that path as main interest at present is difference in calculations between theta=0 and theta=90. The difference being that for theta=0, transverse wind loading, the stepped magnified loading is at centre of the beam. Whilst for theta=90, longitudinal wind loading, the stepped magnified loading is at the end of the beam.

The calculations are a simplification as the maximum moments are calculated for each load condition and then added, but the maximums do not occur at the same locations. Which is why I have another worksheet which calculates moments at several locations along the beam. So I went back to looking at this worksheet, and checking it against the calculations of the new worksheet. Which poses another problem as the location of the maximum moment for the stepped load at the end of the beam is not included in the incremental moments used to plot moment diagrams.

I keep considering writing an excel/vba routine to generate a Multiframe model  for girt and purlin design. The benefit of using Multiframe is I can extend the model to multi-span beam, and not just consider single span beam. With AS4600 built into Multiframe,  can also include axial strut load in the purlins in combination with bending. There is also the possibility of shifting the location of the high pressure zone, putting into an iterative loop, and finding the position which produces the maximum overall moment.

May have to look into whether Multiframe COM automation permits me to plot any design curve I want along a structural member. it would be useful if I could.

Anycase back to messing with my spreadsheets [23:46].