SEAOC Volume 2 page 217

[McEngr]

Can someone please confirm with me that the maximum moment for out-of-plane wall loads is actually 9.8 feet in lieu of 10.5 feet in the Volume II SEAOC Seismic Design Manual? This has been frustrating me for some time now. This is located on page 217.

 

[kevo_55]

McEngr,

I don't happen to have this book infront of me, but is this for a dogbone style SMF connection?

If so, the different distance might be where the hinge is "chosen" to form.(IE: The center of the coping.)

 

[McEngr]

It's to find the maximum moment for an out of plane load on a masonry wall. That's all they say is, "using simple beam theory, the maximum moment is at h=10.5 ft"

 

[kevo_55]

McEngr,

I remember a similar problem from Williams SE practice problem's book. The reason is that the loading diagram is found on figure 4-7. 9.83' is not intuitive at all, but what if you make an equation showing the shear force function for the entire beam? Simply do the first derivitive and set it equal to zero. Most likely, you'll find that the distance will infact be 9.83'.

On this sort of practice problem I simply used the shear force equations from the steel code and added two together, (Priniciple of superposition) and got my equation.

Does this help?

 

[McEngr]

Hmmm. Yes it does help. I was actually doing it the painful way: summing moments about the base. Then I can get the reactions. I take the reaction at the base and divide by the lower distributed force to get zero shear (ie max moment). You do it a little different than me... probably a little faster with your method. Thanks kevo.

 

[kevo_55]

I'd like to call my way the brute force and awkwardness method......