Vertical Cracks in CMU Wall
Vertical Cracks in CMU Wall
(OP)
See attached photo.
This is a warehouse type building, overall it is in poor condition. The walls are about 24ft. tall cmu, there is no other finish or veneer - the interior is just paint on the cmu. There are lots of cracks in all faces of the structure, many of them almost completely vertical. The owner asked me to look at this as he is claiming they are new and are the result of a recent storm. They are almost certainly not new - but what would you attribute them to? Shrinkage? I am not used to see such vertical lines through CMU, without much stepping.
The roof framing (steel) projects right through the wall, you can see the ends of the members at the top of the photo. This is obviously a source of water infiltration, and expansion due to corrosion of the member ends. However, the cracks don't align with these members in general.
This is a warehouse type building, overall it is in poor condition. The walls are about 24ft. tall cmu, there is no other finish or veneer - the interior is just paint on the cmu. There are lots of cracks in all faces of the structure, many of them almost completely vertical. The owner asked me to look at this as he is claiming they are new and are the result of a recent storm. They are almost certainly not new - but what would you attribute them to? Shrinkage? I am not used to see such vertical lines through CMU, without much stepping.
The roof framing (steel) projects right through the wall, you can see the ends of the members at the top of the photo. This is obviously a source of water infiltration, and expansion due to corrosion of the member ends. However, the cracks don't align with these members in general.






RE: Vertical Cracks in CMU Wall
BA
RE: Vertical Cracks in CMU Wall
The reason that I say that is that if horizontal reingorcint was not provided in the walls as suspected, then what indication is there that any chord reinforcing at the roof level interface with the CMU wall was ever placed? The lack of that reinforcing could allow a crack pattern of this type to occur. To confirm this though, I would have to see damage to the roof diaphragm also in the same general location. I would also think that if this were the case, that would have occurred previously in other storm events, unless this was an exceptional storm.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Vertical Cracks in CMU Wall
The building is 100ft. x 100ft. in plan and about 24ft. tall (single story, just a roof), no control joints anywhere. It's basically a big box.
RE: Vertical Cracks in CMU Wall
RE: Vertical Cracks in CMU Wall
If not, then something else.
It could also be a combination of the two to muddy the waters further.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Vertical Cracks in CMU Wall
RE: Vertical Cracks in CMU Wall
RE: Vertical Cracks in CMU Wall
MOPE - There aren't any perp. walls framing in, at the interior it's all one volume except for a little mezzanine area.
Here are two more pictures. The walls are cracked all over the place. Not all cracks are vertical, there is a mix of step cracks and vertical. Some of the step cracks emanate from corroding lintels or pocketed beams so those are easy ones. In most instances that is not the case though.
RE: Vertical Cracks in CMU Wall
RE: Vertical Cracks in CMU Wall
You know, a good elevated diagram of all four walls with the crack patterns shown could tell you a lot, associated with the direction of the prevaining winds.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Vertical Cracks in CMU Wall
It certainly does not look like a properly engineered and built building.
The vertical cracks are probably a result of inadequate control joints that were preexisting and cause some unusual crack patterns.
I would not be surprised for there to be no joint reinforcement. This could also contribute since it theoretically is nor "reinforcement" according to most codes, it does add to the wall performance and continuity.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Vertical Cracks in CMU Wall
RE: Vertical Cracks in CMU Wall
But stepped cracking which the crack width is tapered can also indicate differential settlement of your founds... again look for other signs like distortions in your ground floor plate.
Taking a laser to the grout joint wouldn't tell you much because it looks bad to begin with.
just another view.
RE: Vertical Cracks in CMU Wall
One interesting observation I got from my trip... building owners seem willing to spend big money to assure they will have no problems with the next 50 year storm (or was it a 100 year storm?). Sandy has a lot of people thinking about the next time they'll be struck by lightning, so to speak. Doesn't make economic sense to me.
RE: Vertical Cracks in CMU Wall
Notwithstanding the fact that some of these buildings have been standing for many years, they are inherently dangerous.
RE: Vertical Cracks in CMU Wall
RE: Vertical Cracks in CMU Wall
chris magadia
www.chrismagadia.com
ChrisMagadia.Com - The Structural Engineers' Forum and Resources Website. Civilizations owe its existence to Structural Engineering. Do you Agree?
RE: Vertical Cracks in CMU Wall
Looking at the photos provided by bookowski, how did you conclude that the wall cracked under compression loads? It is a warehouse building, so the compression load would be only the dead weight of the roof and the wall itself.
I would have thought that vertical cracks were caused by tension normal to the cracks.
BA
RE: Vertical Cracks in CMU Wall
RE: Vertical Cracks in CMU Wall
RE: Vertical Cracks in CMU Wall
Other than that, to me it's obvious those cracks are old, and everyone here is on track with shrinkage effects. And the building clearly has a water penetration issue, which will do its evil deed over time, particularly in the northeast. Any Local Law 11 guys out there?
As for the question of what do you recommend, I'd need more info. I couldn't go by just the wall pics. Shoring the roof and rebuilding a wall at a time would be a lot cheaper and less disruptive that a tear down. The NJ Rehab Code would also be on your side.