control joints @ large openings
control joints @ large openings
(OP)
I have a project that has three 40' long walls with a pair of 14'-8" openings and returning walls at each end. (See attached elevation)
This project is in a high seismic area (SDS D) and the piers are designed as shear walls with bond beams at 16" o.c. with hairpins at each end. The walls are also load bearing. There are 32" deep lintels above the windows with 2-#5 top and bottom and the chord reinforcement bond beam and top of parapet bond beam above that.
I cannot see anywhere to put a control joint in these walls so I am inclined to put no control joint in these walls. Opinions?
This project is in a high seismic area (SDS D) and the piers are designed as shear walls with bond beams at 16" o.c. with hairpins at each end. The walls are also load bearing. There are 32" deep lintels above the windows with 2-#5 top and bottom and the chord reinforcement bond beam and top of parapet bond beam above that.
I cannot see anywhere to put a control joint in these walls so I am inclined to put no control joint in these walls. Opinions?






RE: control joints @ large openings
RE: control joints @ large openings
Where are you climate-wise?
As a seat of the pants suggestion (not a recommendation without more information), I would suggest control joints just off the openings and at an appropriate distance from the corners. Just a detailing suggestion.
Dick
RE: control joints @ large openings
The project will be located in northwest Washington State and the climate is temperate but damp. The site gets 20 inches of rain annually with temps between 30 and 80 degrees.
When you say "just off the openings" I assume that you mean into the jamb rather than over the openings. I had thought about that possibility but how would you deal with the 2'-0" required minimum development of the lintel bottom reinforcement. This would also interfere with the tension rebar for the shear piers.
I am attaching a 3d view of this section of the building.
RE: control joints @ large openings
BA
RE: control joints @ large openings
Mike McCann
MMC Engineering
RE: control joints @ large openings
Most of the articles I find on control joints talk about putting control joints at locations where the wall changes height or at the edge of openings but all of the examples they have show the joint in the middle of a big section of full wall. No one ever wants to show the tough stuff.
With all of the reinforcement I need at my openings it doesn't make sense to put a joint there. I am attaching a view of where I plan to put my joints. Any comments or suggestions?
RE: control joints @ large openings
Dik
RE: control joints @ large openings
RE: control joints @ large openings
I had considered putting a joint at the side of the opening. In the attached sketch the two possibilities are the blue line and the red line. I don't like either one. The blue line run right through the anchorage for a cable suspended awning. The red one doesn't leave much wall for the out-of-plane lateral forces at the jamb. It seams to me that the amount of reinforcement will keep the crack width to an acceptable level and that the joint are not needed.
I think I will put a CJ at the intersecting walls at RE and RF as DIK mentioned.
RE: control joints @ large openings
BA
RE: control joints @ large openings
The grids are on the elevation in the original post. On the 3d views these grids are at the section of the wall that extends 4 feet beyond the walls with the large openings.
I would rather not put a CJ at these intersections if it is not needed. I am thinking that because the section is so much less at the lintels, most of the stress due to the shrinkage will be concentrated there. Given the amount of reinforcement required for the lintel design the cracks should be tight enough to avoid problems. This is especially true due to the lintels being grouted solid up to the diaphragm bond beam which is continuous in any case.
RE: control joints @ large openings
BA
RE: control joints @ large openings
Do you or anyone else see a problem with enliminating the control joints at the intersecting walls at grid RE and RF given the amount of reinforcing?
RE: control joints @ large openings
There is a potential for cracking at the end of your heavy reinforcement. Reinforcement does not continue through the intersecting walls, so a control joint at the exterior face of that wall would seem a good idea.
BA