Cracking in existing masonry

[SinanMaimar]

There is a fairly large attachment to this long post including several pictures, a partial plan and a partial elevation view. It’s an existing 4 story structure from 1950s with load bearing brick walls and concrete on bar joist framing.



There are two locations of significant cracking within the existing masonry along the west elevation of this building. This attachment shows cracking along at the south end. There is similar cracking at almost identical mirror location to the north. My goal is to determine the cause/causes of the cracking and suggest a repair procedure.



To summarize the pictures:



Existing walls are 16” multiwythe brick. This story is a partial basement. And I guess this would be my first question: I can’t tell from the drawings if the brick continues below grade. Was use of brick as basement or foundation wall ever practiced? I am wondering if below grade (on the exterior face) the brick is replaced with cmu or even concrete. The gap between existing ceiling and wall (pic 2 & 4) indicates movement of the walls to the outside at the top. The wall is bowing in at the crack location (pic#1).



I did not see any expansion joints along the whole elevation and I wonder if the cracking is partially due to that.
There is also evidence of water infiltration at the roof level and I believe that is a contributing factor.
Caulking within the cracks at the exterior suggests that this cracking has been around for a while.


I have other pictures but did not want to post a very large attachment. Obviously I am requesting some insight from the participants here to help me out a bit.

 

[ajk1]

I have seen cracking like this at a jog in the wall on a project a couple of years ago. I believe that it is mainly due to the expansion/contraction of the long wall; when it expands it causes a moment on the short portion of wall that forms the jog. If they had an expansion joint here the crack probably would not have occurred.

To your question of whether brick was used below grade, my amnswer is yes it was in the latter 1800's and early 1900's in the area in which I reside (Toronto).

 

[ishvaaag]

Really looks as if consistent with temperature change, since exceeding common proportions without joints. There may have been some contributions of other factors, setllement or heave on volume change due to changes in water content etc. Some of these cracks maybe even seasonal, on clays taking more or less water with the season.

 

[SinanMaimar]

ajk, ishvaaag:

Thanks for the input. What did you guys think of the last picture. It appears to me that a crack occurred because of lack of control joints, then water was absorbed and masonry expanded.

 

[concretemasonry]

Keep in mind that clay brick has a long term expansion that requires spaced joints horizontally and vertically for sound construction.

That is a long building, so the expansion can produce large forces to resist the expansion.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[SinanMaimar]

concretemasonry:

You are right, since the building is 60 years old, I think all the movement that had to happen took place long ago. Your comment about the expansion explains the bowing out of masonry on the few locations I noticed, that makes sense.

What sort of remedial measures would you think would be required. I was planning to reinforce both sides of the crack in the basement (pci#1) with steel angles bolted each side of the crack. I am not sure about the bowing out over the windows (last pic).

 

[ishvaaag]

Really that out of plane deformation is what makes me to think there may have been some contribution from movement at foundations; if predominantly local, however, it maybe an effect of seasonal closing on the crack refilled, then being forced out of plane either from temperature or material's changes. It may also be that the movement at the foundation has been compatiblized at the lower part of the wall with some bigger discontinuity.

It is also worth to mention that I have observed a number of times on buildings that have wings, or even closed patios, and this one can be one more of them. However since the building is so old it points to some change, local excessive heating, water content change, etc.

 

[concretemasonry]

Even though the building was old, most of the expansion could have been during the last 20 or 30 years, when the mortar shrinkage was completed.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[ishvaaag]

Maybe, but the most clear case where I found non-structural brick cracks of thermal cause at one building of 55 m maximum dimension the cracks, near 1 cm (where no parapets, that went bigger) manifested in the first year after construction... I used to say for structural pathologies that when something happens normally a chain of circumnstances might have occurred.

 

[apsix]

Example of short return cracking and remedial work here;

http://www.actionwallties.co.uk/com...with-short-wall-returns-expansion-joints.html

 

[ajk1]

Has the wall condition been like this for a long time? I once had a project where the wall footing had been placed on a hemlock timber sill and it worked fine for almost a 100 years, then a municipal sewer project lowered the wate table,and during the follwoing 10 years various signes of settlement were noted in the building. The cause was that the wood was now above the water tabkle and of course rotted and the wall settled. We had to dig down under the wall to find out all this.

 

[JoeBaseplate]

Sinan,

Could you send your info to masonry restoration contractor for an opinion!