Existing OWSJ Evaluation.

[steve111]

Looking for opinions on how to determine the capacity of existing owsj when you have no information wrt. manufacturer, manufacturers span tables, proprietory info., etc., but can field measure geometry, and member sizes. Especially interested wrt. modelling nodes, top chord assumptions and eccentricities. Thank-you

 

[imcivilized]

Steve111;
There is another similar thread I've been following as well, which is related to this..

It is entitled "Existing open web steel joists"

I'm sure you've hit it by now, but other than getting the original fabricator, I haven't seen much that's very exact.

I'm hoping someone has done a program somewhere that you could enter the components of the top/bottom chord and web material to get properties, but nothing yet.

 

[jheidt2543]

When dealing with existing OWSJ of an unknown brand etc. the first thing I try to find is a one of the original joist shop tags. They are rarely removed and if you find one, they give most of the basic information you will need. With that information and a few field dimensions, a call to a local joist supplier or the SJI will usually get the resest of the information you want.

Yes, you can, given the time and inclination, try to compute the joist capacity. However, I think this is too time consuming and of little real value, because of all the information you don't know about an existing joist. Look for the tags and call the numbers in to a joist supplier.

 

[steve111]

Vmirat, yes read the thread 'Existing open web steel joists' very good comments by PM, ie, your 'lucky if you can find a tag'...try digging around thru ceilings, fireproofing, M&E, etc., to find a joist mrk. no. only. Suppliers/Manufacturers can be helpful but their limited by; time ie project constructed long ago, or their busy with current work ... and protecting their propietory knowledge, and i feel sometimes potential liability. There are alot of curiosities out there that defy analysis and one assumes were proved by testing, and designer/manufacturers that no longer exist .... ??? Original structural design drawings are of questionable value, and shop drawings from time of construction are very difficult to locate. It is strange that such a common occurance in structural engineering ie evaluating an existing owsj system (a major structural component) for a change in loading etc. seems such a difficult task. This problem isn't limited to owsj, we also find it with wood trusses/truss plates .