Truss Design - Light Gage

[McGill10]

Hello
we are using Light gage truss for roof and light gage studs for wall/shear wall on a single story building . To make a lateral load path from Roof to shear wall I need blocking members between trusses where truss sits perpendicular to the stud shear wall.
As the trusses are more than 2ft of depth, what will be the best blocking system? Using two 12 in deep studs sections on top of each other to make 24 in deep?
any experience and solution is highly appreciated.

 

[XR250]

This is always a complicated issue and gets neglected more often than not. We call it heel blocking. If really depends on the magnitude of the shear.
How much shear are we talking and what is the truss spacing?

 

[spats]

Why is the heel/bearing depth of the truss so tall? Can't you use a "normal" height of 5-6"?

 

[McGill10]

The Shear we will get will be on the range of 4000-5000 lb.
We need deep heel because the roof is monoslope. Also in some areas the truss span perpedicular to the roof slope requiring supporting wall to slope.

 

[msquared48]

Sounds like you need to fabricate some special trussed truss blocking.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[woodman88]

Here is a link to Structure Mag about bracing that shows ways to block between the trusses.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[ron9876]

I agree with blocking trusses idea. Have had to do this with wood trusses.

 

[McGill10]

That's a good article answer lot of questions.

 

[XR250]

4-5k over how many trusses? Also, what is the truss spacing.
Remember that each blocking panel is essentially a mini-shearwall that requires the ends to be tied down and the bottom to be fastened to the track and the top fastened to the roof deck. There ain't no free lunch on these things.
Can you use top bearing trusses and run the studs up higher? - usually makes things easier.

 

[McGill10]

Shear Wall being 12 ft long and spacing of cold formed metal truss is 2ft,so let's say 4-5 k shear over 6 spaces. I agree top bearing trusses would make things easier for blocking.I was assuming bottom bearing truss is in the practice mostly.

 

[XR250]

That is a lot of shear over that distance. Getting the ends of the blocking tied down may be a chore. I would try to use top bearing trusses if at possible.