Timber Truss Florida Building Code

[tclat]

Hi,

I have a timber truss fabricator from Florida who has supplied us with some shop drawings for review. The trusses are for a hotel in a hurricane prone region outside the US which is why the developer has engaged a fabricator from Florida. The trusses are generally for building blocks that are up to three stories and have as many as 40 units. The drawings indicate that the trusses are to FBC 2017 RES which I imagine is the residential building code which I'm not familiar with. What are the primary differences between the regular FBC and FBC Residential and would this code be applicable for the buildings I describe?

The trusses are spaced at 2 feet c/c and will have 3/4" ply over the top. Looking at their numbers and truss drawings, the top chord clear span between webs is as much a 7 feet so there would be local bending in the top chord. I only see references to the axial loads in the members. Do truss fabricators typically ignore local bending in their designs?

Thanks

 

[JedClampett]

Take a look:

https://codes.iccsafe.org/public/document/FRC2017

 

[Ron]

A hotel is a commercial structure, not a residential structure. Both the Florida Building Code and the International Building Code make this clear in Chapter 1 of each of the respective codes.

With that in mind, the trusses should be designed to the FBC-Building, not the FBC-Residential.

 

[Mjkkb2]

I don’t have much experience with Florida residential code. However I would change your title to woood truss instead of timber as the latter is typically used for a large volume/timber truss and not metal plate connected wood truss ( which looks like is what you describe)

 

[JedClampett]

The OP said that this was not in Florida, but in an island with similar winds, so the use of the Florida Residential Code might of been acceptable option, even though it's not residential. Basically, it's better than nothing. Plus, wood truss suppliers mostly do residential, so that's their default.

 

[tclat]

Thanks for the comments. I was able to review the link provided by JedClampett.

The Residential Code has a maximum design wind speed limit of 140 mph (I imagine this is based on ASC7-05 and not ASCE7-10 which specifies ultimate wind loads). I will ask the fabricator to change the code spec to FBC -Building.

Any comments on how they these fabricators typically deal with local bending of the top chords? Do they typically simplify the applied load to point loads at the nodes to eliminate the local bending in the top chord? Their design report only lists the axial loads and no reference to bending moments.

 

[Ron]

tclat....it's a truss...generally only axial loads are considered. Bending is neglected.

 

[XR250]

tclat....it's a truss...generally only axial loads are considered. Bending is neglected.

Robn/tclat, I believe that limit state is checked but not shown on the typical truss output. I certainly check it when I am analyzing a truss member.