Horizontally Spanning CMU and vert control joints
Horizontally Spanning CMU and vert control joints
(OP)
I searched the forums and nothing came up, so I apologize if this has been asked.
I have a tall CMU wall that spans horizontally 12' to pilasters. Wall lengths are in the neighborhood of 116' each. The wall works spanning horizontally and the pilasters work vertically. My question is about the vertical control joints. Since my wall relies on the horizontal continuity of the bond beams, can I use greased bars or something similar to transfer the shear across the joint? Is this a standard practice? Do these dowels need to fully lap with the horizontal bars?
Thanks for your time and input.
I have a tall CMU wall that spans horizontally 12' to pilasters. Wall lengths are in the neighborhood of 116' each. The wall works spanning horizontally and the pilasters work vertically. My question is about the vertical control joints. Since my wall relies on the horizontal continuity of the bond beams, can I use greased bars or something similar to transfer the shear across the joint? Is this a standard practice? Do these dowels need to fully lap with the horizontal bars?
Thanks for your time and input.






RE: Horizontally Spanning CMU and vert control joints
That is an interesting problem...I would think a shear key or unbonded dowel could be used to create the joint separation. Maybe also consider having some sort of "double pilaster" with a control joint in between?
regards,
Michel
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
The approach you have is very different from used on many thousands of buildings around the country. Most are industrial/commercial office warehouse buildings using 12" CMUs and are 16 to 24' high with pilasters at about 20-24' O.C. and control joints at one side of each pilaster. The pilasters are 16-24" deep and are turned to project inward or outward, depending on the functional interior use of the buildings and architectural appearance. More information on your design challenge is necessary, since you may be using a concept based on a different geometric requirement.
Details are a different story and construction of a control joint that can effectively transfer the loads well enough to be considered as a moment connection is very, very difficult and costly. At the face of the wall, it is much more reliable and more pleasing architecturally, especially if the CMUs must have an architectural appearance. Turning the pilaster so it projects into the interior is very common to build a wall with just joints at the pilaster and no projections outward
How tall are the walls?
Is there any vertical loads on the top of the walls.
Is there any lateral support at the top for the roof system/deck?
Are the 12' pilaster spacings determined by architectural or the goal to force the wall to span horizontally between the pilasters?
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Horizontally Spanning CMU and vert control joints
This may not be as common as spanning the wall vertically, but I have done it many times. That type joint also works in fully grouted walls.
RE: Horizontally Spanning CMU and vert control joints
BA
RE: Horizontally Spanning CMU and vert control joints
Much depends on the part of the world you are (wind, seismic) and the traditional methods that contractors can do quickly and easily to a high quality if this is a typical box like a gym,retain store or office warehouse. If it is "one-off" type structure like a school gym, auditorium or similar.
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
I wouldn't like to have 6' sections of wall cantilevering each side of a pilaster. By all means, put the joints central between the pilasters, but run the horizontal bars through.
Various opinions, now it is your call...
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
RE: Horizontally Spanning CMU and vert control joints
for your wall, how do you reinforce them? horizontal bars between pilasters?
"Most are industrial/commercial office warehouse buildings using 12" CMUs and are 16 to 24' high with pilasters at about 20-24' O.C. and control joints at one side of each pilaster. The pilasters are 16-24" deep and are turned to project inward or outward"
RE: Horizontally Spanning CMU and vert control joints
BA