Brick Structure Out of Plumb

[JNEnginr]

I inspected a Brick structure. Old building. (2) wythe thick walls (8" total), 3 storys in the front (32' tall), 2 storys in the rear (21' tall). Its a residential building, row home 16ft wide x 55ft deep, with no adjacent structures to the left or right. Plumb bob has the left side of roof 11" away from foundation, right side about 9" in the same direction. This is worst case at the middle of the building. Towards the front of the building and towards the back are only 5" out. It seems like they removed a rear wall for an addition in the past which is most likely why the shifting started. Foundations are in great shape with no signs of settlement. Its been this way for awhile, as the current finishes take into account the leaning (i.e. trim finishes widen to accommodate).

The repair? I'm thinking steel channels on the outside of the building with tension ties in the floor to prevent future separation (the floor joists are almost out of the pockets).

But globally, recommendations for pulling the structure back upright? And keeping it there? Steel Frame? This is a renovation job so interior is completely gutted so not worried about redoing finishes, just salvaging the structure.

Thoughts are always appreciated.

Thanks,

 

[thaidavid40]

If the footings show no signs of settlement, why is the structure leaning so badly? This data might drive the selection of the best solution.

Thaidavid

 

[hokie66]

An 8" brick wall leaning 11", and floor joists almost out of pockets sounds like a very unsafe condition. Has consideration been given to demolishing and starting over? At the very least, substantial and tricky reinforcement of the existing structure will be required if the building is to comply with current codes, so an entirely new building may be more economical and serviceable.

 

[JNEnginr]

Demoing is definitely on the table. I'm just trying to see if reinforcing is possible, and if anyone has experience with doing so. Methods, etc

 

[msquared48]

Sounds like building has seen movement from seismic forces in the past, leaving permanent deformation.

Mike McCann, PE, SE (WA)

 

[JNEnginr]

Any recommendation on fixing said deformations? Or does everyone feel as uncomfortable about this as I do.

 

[SlideRuleEra]

I would not even consider trying to reduce the lean. You would have to pick specific locations to apply force to plumb the walls.. and you don't know if, or where the correct locations for force application are. Pick the "wrong" spots and probably make matters worse.

One more check you can make. See if the foundation is level; it may not have settled, but perhaps the building has always had a certain amount of lean that has gotten worse over time. If the foundation is not level, that would be a good reason to seriously consider demolition.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[bookowski]

That is a very precarious situation. First step should be shoring the floors and bracing the building - the fact that it has been this way for a while isn't a guarantee of anything and the demo could be enough to tip the scales. Removal of the original rear wall may have been the initiation of the lean.

If there is a compelling reason to retain the building it can be done. It's not uncommon in my region to stabilize such buildings, usually because of historic or other reasons that make demo difficult. If you go this route you are really building a new structure and tying the existing stuff to it. You ideally want a stiff structure - steel framing with braced frames is best if it's an option. Steel can be fished through the existing structure relatively easily and the new structure built around the existing.

Two wythe walls don't work for out of plane loads and it's likely the mortar is shot as well. You'd probably want to retrofit anchors to a new wall backup.

It can be done - but demo should be considered and in either scenario bracing, shoring, and protection prior to any work.

 

[msquared48]

The walls have deflected because the floor and roof diaphragms have failed - probably no chord force provision along the long wall.

I am with JAE here. I would not try to correct the deflection. I would try to figure out WHY this abnormality occurred and see if a reasonable approach can be devised to prevent further deflection. If not, bring it down.

Mike McCann, PE, SE (WA)

 

[manstrom]

Instead of a channel on the outside, make it decorative. These are all over the place in old Charleston. I did something similar with square plates at a renovation in CT.

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[SlideRuleEra]

The bolts that manstrom showed are locally referred to as "earthquake bolts". They were retrofitted to buildings in Charleston after the devastating 1886 earthquake. They span from one exterior wall of a building to the other... to try to keep the walls from falling "out". Since there has not been another major quake since the 1886 event, it is not known if they are effective. In JNEnginr's building I doubt if they would help - both exterior walls are leaning the same way. If the worst wall (11" lean) fell the bolts would increase the likelihood that the opposite wall would come down, too.

Here is some historical info on earthquake bolts:

http://www.ccpl.org/content.asp?id=15729&action=detail&catID=6045&parentID=5748

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net