Force Transfer around Garage Doors and even bigger 1

[YoungGunner]

The SDPWS does explicitly permit the aspect ratio for force transfer walls to consider the aspect ratio for doors, though there aren't many great methods of calculating the strap force in those segments. This also opens up a can of worms of whether for taller walls, we can effectively still only use the aspect ratio for the door? See images for examples, assume the tall versions have no floor system breaking up that wall height. My specific questions:
1. What method do you use to calculate strap force for a garage door scenario?
2. Are there any scenarios below you would flag as "not acceptable" for force transfer?
3. Where windows stack, what do you do about aspect ratio?
4. What do you do about designing the hold-downs for the piers?

 

[phamENG]

I do not use them for doors. There's a good document out there (I'll look for it later) that breaks down physical tests to evaluate several of the popular methods. None of the doors were anywhere close to the predicted performance.

If I need it at a door, I use a site built portal frame or a simpson strong wall. APA has a white paper that gives capacities for the IRC portal frames for engineered applications.

 

[PSAHCE]

hi,
i have faced same problem several times.
if you are dealing with lateral(wind) loads then, there are two ways.
if you have wall on 2nd floor which does meet the aspect ratio,
you can just use that wall as shear wall on 2nd floor and then use APA portal frame or
simpson strong wall to the garage door opening on both sides.
if not so or not having a floor then,
you have only one option to go for steel frame design.

thank you

 

[JoshPlumSE]

1. What method do you use to calculate strap force for a garage door scenario?
**I use anchors at any full height openings. If you do this then Force Transfer Around Openings (FTAO) still applies and can still help reduce anchor forces due to 'frame action' of the wall when compared to an analysis where you ignore the wall above the opening and only consider the two piers. But, in some cases the Perforated wall method (when allowed) can be applied (I believe) though I don't generally do so.**

2. Are there any scenarios below you would flag as "not acceptable" for force transfer?
**Whenever you don't have hold downs on both sides of a full height opening.**

 

[80PercentTruth]

@YoungGunner

This is a classic case which I see on many residential structures. I prefer to drag the shear load further down the wall line away from the garage and use a portal frame at the garage to serve as a collector element. If the house is skinny and this is all you have, you will not be able to get capacity out of a wood portal frame and will have to consider a simpson strong wall, moment frame, or a cantilever column system. As with @phamENG I do not find it appropriate to use FTAO at doors.

"Engineers only know about 80% of the truth, the next 10% is very difficult to achieve, and the last 10% impossible. If we are bound to be wrong, we may as well be wrong simply and conservatively."