Long Span Wood Trusses

[Inzynier]

I am looking for references or examples of project application of long span wood/glulam trusses (US experience preferred). My current project involves roof trusses spanning nearly 100 ft over assembly hall. It probably can be done but I am personally not familiar with wood roof trusses exceeding 60-70 ft. Experience sharing would be helpful. I will welcome any suggestions.

 

[boo1]

I have found truss length of 80 feet is the shipping limit.
Group/gang truss erection may be a good requirement for long trusses. Spreader bars are a must. The connection design and bracing (temp and permanant) are critical.

Consider Light gauge steel trusses they have been found cost effective in non-combustible construction, including 4 story or more hotel type buildings having attics without sprinklers and with fire stops. Insurance for non-combustible construction can be one third the cost relative to combustible construction.

 

[Inzynier]

In this particular case, project requires scissor truss spanning 95 ft over a church assembly hall. The architect insists on wood truss because of its "visual appeal".
The scissor truss could be shipped in two components 42.5 ft long each and spliced on site at the center. I am not sure however whether there are many wood truss manufacturers in Midwest who are able to take this assignment. This truss can be designed. Manufacturing and erection is what we are mostly concerned about.

 

[boo1]

Umm, maybe call a few truss plants. The wood truss web site in the US is:

http://www.woodtruss.com/

 

[Trussdoc]

Trus-joist has a division in Canada that makes long span trusses out of engineered wood with plate steel connectors. The lightweight 2x_ wood truss made by most fabricators is just too flimsy for this application, and does not look very nice.

 

[Escher]

While I know you are looking for US examples there is an excellent collection of structural wood engineering information brochures called Informationsdienst Holz (German. One of these is Fachwerkbinder Berechnung Konstruktion dealing with what we call in Australia Architectural Trusses. Large span widely spaced exposed trusses. There are worked examples and design aids. While I can't speak a word of German I can understand the information presented if I have my German-English dictionary at my side.

Of course it helps if we all speak the same units (they persist taking in cm while here in SI land we talk in millimeters & metres).

If you prefer you may find an old copy of (Timber Engineering Company Washington DC) TECO's book Typical Designs of Timber Structures 1949 edition in an educational library. While the Codes have changed it may be a useful starting point.

A point worth noting is the failure of some old timber structures in tension connections recently reported in this forum. This was observed in Australia more than 15 years ago and resulted in the Australian Code increasing split ring connector end distances substantially.

 

[RARWOOD]

This is an old post so my replying to you now probably is not helpful. Hoepfully you learned that there are atleast three companies in the Minnesota and Wisconsin, including the one I work for, who could manufacture the trusses and several who could erect them.

There are also companies on the East and West coast along with ones in the South who could manufacture the trusses and who do bid other areas of the country.

To me the design would be the difficult part. In our shop we assembled a beam by bolting four 6 3/4" x 72" deep beams togeher. The beam weighed just over 50,000 lbs. We were able to lift it in our shop and set it on a flat bed for shipment. Our erector then had no problems lifting and setting the beam. I am sure there are several other companies in the U.S. who could of handled the job also.

So if we picked up a project like that my concern would be on the design. The most important thing is that the architect has to give you the truss depth you need.