Scaffolding Codes

[JohnWN]

I have nearly finished a beam analysis program specifically for Temporay Works.<br>
I have used the British codes and tube and I would now like to configure it for the USA<br>
<br>
Can anybody tell me:<br>
Are there specific codes in USA for steel and timber for Temporary Works?<br>
Is scaffold tube the same ie. 48.3 o/d * 4.0 wt.?<br>
If you could also tell me the permissible bending moment of tube, that would be very helpful.<br>
The titles of any good books on the subject.?<br>
<br>
<br>
John Watson<br>

 

[RiBeneke]

I find the subject of your analysis program interesting, and would like to hear more when you have done . . .<br>
Here in South Africa the 'scaffold tube' that is used is made from so-called 'high-yield steel', and the yield strength is 340 MPa (similar to BS Grade 50) from most manufacturers. However, you should remember that the couplers used will often cause a buckling of the tube at the load points long before this yield point is reached in simple bending.<br>
Your BS5975 'Falsework' code of practice (esp Appendix B) may also be of help.

 

[JohnWN]

I had not thought about South Africa but all info is useful. I am entering the scaffold tube into a fixed database using the max bending moment In the uk we do not generally use high yield tube for tube and fitting scaffolds so I have no data. If you could give me a working stress, and a code for reference, I could add it to the database.<br>
As for more details on the beam analysis program. I gather I am not allowed to advertise and I don't think that I can contact you direct so I can only suggest that you do a search to find my site.<br>
Briefly the program will have lift off supports, an editable database for soldiers, ladder beams etc and the facility to use or check the moment provided by a double coupler.<br>
Are you using BS5973 and 5975 in SA ?<br>
<br>

 

[RiBeneke]

Sorry that I have not responded sooner.<br>
I do not think that it would be correct to use only one value for the bending moment limit in your program. Try a simple test : Clamp a horizontal tube between two uprights using your standard fittings and load it with planks carrying bricks etc. On a short span the tube will probably fail by crumpling at the fittings. On longer spans the deflection limits what can practically be used.<br>
However, as a general guide, you can probably assume a yield stress of 200 to 270 MPa in the mild steel cold-formed tube before buckling occurs at the support points. For allowable-stress design methods, you would factor this by say 1.6 (non-critical apps) or 2.5 (life-critical apps) for temporary works design.<br>
Here in SA we have a very simple and somewhat old-fashoined scaffold code of practice, so I prefer to use the BS codes for serious temporary works structures.

 

[JohnWN]

That's OK but I am trying to use recognised norms not define then.