Tilting Boundary Wall 2

[civeng80]

A portal framed building with concrete panel cladding has a wall about 45m (145ft) long built on a property boundary. It’s about 8 years old and now the wall is tilting outwards and very serious cracks are showing in the slab inside and timber wall partitions are separating from the outside wall by up to about 30mm (1 inch).
The soil in my opinion is pretty good. A safe bearing capacity of at least 200kPa and neighbouring buildings don’t seem to have any structural issues (apart from small shrinkage cracks in slabs).
I have some interest in the land adjoining the building and now the client wants to build a load bearing concrete panel adjacent to the existing wall.
The footing system of the tilting wall is shown (dimensions cannot be verified) but it is an eccentric pad footing with both the wall and edge of footing on the boundary. Now this is well outside the middle third (kern of the section) and I’m pretty confident that the reason for the tilt is because of the eccentricity and resulting moment and rotation.
Has anyone any idea how it can be fixed and how to construct the footings for the building adjacent?

 

[BAretired]

I agree with your conclusion about the reason for the tilt. When the new strip footing is poured, I would suggest tying the two footings together so that the load is more or less aligned with the centroid of the combined footing.

BA

 

[hokie66]

In addition to the eccentricity of the gravity loads, the thrust from the portal frame column would be contributing to the movement. As there are two owners involved, and as your new building will likely be relied on to stabilise this existing problem, the two owners should collaborate.

 

[BAretired]

Good point, hokie. Maybe their lawyers will need to write up an agreement respecting future demolition of either building.

BA

 

[civeng80]

This perhaps could stabilize the wall from tilting any further. Do you think the wall could be jacked up before stabilizing with the new strip footing? I know of a company that pressure grouts slabs that have sunk (dont know how sucessful they are) but could it be applied to the footings to jack up the wall before stabilizing with the new footing?

 

[civeng80]

Thanks all !
Any comments on actual repairing the wall prior to tying ?

 

[hokie66]

If the concrete panels are tilting outwards, I assume that the portal frame columns are tilting with them. Maybe it is the portal frames which are deflecting, and the panels are going along for the ride. Have you analyzed the frames? Some of these portal frame buildings I see around the place look very skinny...very flexible.

 

[msquared48]

Depending on the load to the footing and allowable soil bearing, the use of pin pile centered under the wall, not the footing, might work to arrest any further tilting.

However, returning the wall to it's original position is another matter.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[dicksewerrat]

Is the tilt only on one side? What about the roof?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[civeng80]

I’ve had just a general inspection inside so nothing really detailed. The drawing that I submitted only shows the type of footing and the sizes of members is not the same as that used in the building.
The panels are clipped on the columns and as far as the portal is concerned it does look a little skimpy but not to the extent of causing such a huge problem. I recall when the footings were excavated and poured 8 years ago and was always a bit apprehensive about the eccentricity and the fact that the panels and line of the footing were on the property boundary.
My client is concerned that the owners would like to enter his property and do excavations to the base of the footings to see whats going on. I advised him not to let them do this as it could have a serious effect on his future footings which we anticipate being strip footings.
The other side doesn’t seem to be a problem and I don’t know about the slope of the roof.
I do know definitely that something very serious is happening to the boundary wall.

 

[BAretired]

Maybe a meeting could be set up with the interested parties, including you and the other engineer in order to discuss the problem and how it might best be addressed.

BA

 

[hokie66]

If the panels were right on the boundary and are tilting outwards, there must be a degree of encroachment on the adjacent property. Acting for the adjacent property owner, I would want a survey of the wall to quantify this encroachment. In the absence of cooperation between the owners, a letter from a lawyer might be the next step.

 

[civeng80]

Looking from a legal point of view thats a pretty good idea hokie and could be used as a last resort.