How does a Blocking Panel distribute load? 1

[EngineerofSteel]

I have a roofing remodel project.

Two existing buildings are perpendicular to each other. They have flat, built-up roofs. The owners are re-roofing with 4:12 trusses. The new trusses will overhang an additional 5 feet past eaves. There will be one continuous roof covering both buildings.

These are small bldgs. 17x40 & 30x56

Here is my question:

There is a "blocking panel" at the top 2' of 10' walls. They range from 2'x17' to 2'x55'10". They are designed by the truss company "unsheathed designed for 600 lbs" .

below the blocking panel are 2x4 walls with 7/8" stucco. This is in Sacramento, seismic zone 3, so the allowable seismic resistance is only 90 PLF, half the 180 PLF allowed for wind.

Q: Can I design this blocking panel as a shear wall and design chords at the ends for axial requirements only?

I just can't see how the original designer justified the walls.

Below the blocking panels

 

[cg3375]

I've seen these truss frames done and engineered as drag struts with the plf load applied when the plates couldn't handle the full horizontal load.

These were different than blocking panels placed between trusses or rafters with high heels to get the roof diaphram load down to the wall or to prevent rotation.

 

[EngineerofSteel]

Thanks cg3375.

I think you are correct. Some of the walls have a lot of doors and windows, and load transfer could very well be the purpose.

I am just unable to see how the previous designer justified the stucco walls to transfer the seismic loads.