Structural Clay Tile Basement Walls

[PSUengineer1]

Group,
I am interested in learning more about structural clay tile basement wall failures. From my humble experience level with this material I observe that the walls fail typically as a result of lack of reinforcement in the horizontal cells and inadequate wall design. In addition, the walls many times fail as a result of horizontal earth pressure and hydrostatic pressure from water (i.e. additional pressure from saturated soil).

As I understand it, the walls must be supported at their base (generally by footing or concrete slab) and at the top by the floor structure.

The distribution of the total lateral load between the vertical and horizontal span of the wall depends on the height and length of the wall, and its stiffness in the spans. The lateral load on a basement wall will be carried entirely in the vertical span when the length of the wall between supports approaches three and a half to four times the height, according to the Handbook of Construction Contracting (Vol 1 Plans, Specs, Building by Jack P. Jones).

Questions:
1. Wall stiffness in the vertical span can be increased by embedding vertical steel reinforcing but how in the world do you reinforce structural clay tile vertically?!?!?!?

2. Has anyone out there observed structural clay tile basement wall failure in the horizontal span (vertical crack)? I typically see structural clay tile basement wall failure on the long walls (vertical span, horizontal cracks).

3. As far as lateral load distribution to the basement walls go, am I on track by using the 3.5-4.0 X height rule of thumb that I stated in paragraph above?

4. Does anyone have a copy of the Handbook of Construction Contracting (Vol 1 by Jack P. Jones)? Is so, would you recommend purchasing it and using it for reference in doing "down and dirty" preliminary engineering calculations?

5. Any reference material that another engineer can provide me with for the purposes of educating myself more on this topic would be highly appreciated.

Thank you.

 

[BAretired]

I have never used clay tile for a basement wall. Are the voids filled with concrete? Why would it be difficult to reinforce clay tile vertically?

BA

 

[PSUengineer1]

Reinforcing clay tile vertically is difficult when the hollow chambers in the tile run horizontally.

 

[BAretired]

So why not run them vertically?


BA

 

[PSUengineer1]

builder did not do it in this case. labor intensive to drill through for rods. bottom line is - wall is underdesigned (see attached pic).

anyone have design calculations for structural clay tile used as a basement wall? I would assume to just use a very low f'm and calculate a bending stress based on a non-reinforced section in this case. A design reference would be helpful though.

any insight is greatly appreciated.

thanks.

 

[BAretired]

You don't need calculations to see that the wall in the photo is unsound. Clay tile may be okay as a form, but you need to reinforce it which means that the cells have to be filled with concrete. If the wall spans vertically, the cells must be oriented vertically.

BA

 

[AELLC]

Wow - that looks like it has zero bending strength. You couldn't even use a very low tensile f'm because there is no grout continuous vertically, and the bond of the mortar to the clay shell is impossible to verify, especially after all the years of moisture intrusion.

 

[dhengr]

Jimjxs263:
I’ve never used clay tile for a basement foundation wall either. I would be worried about their susceptibility to continuous moisture from the soil. Is there any exterior waterproofing treatment on those tiles? They look to be in surprisingly good condition, for this application. But, then they have been laid in the wrong orientation, and they appear to have been laid in stacked bond which is even worse. The movement of the exterior found. wall appears to have caused a crack in the first mortar joint down from the top of the perpendicular interior wall also.

You are not telling us the full story here, that picture looks like there has already been a wall failure and now you might be trying to salvage the remainder of the walls. Clay tile worked great for interior partitions, or backup for exterior brick cavity walls, even for lightly loaded bearing walls, without significant lateral load bending tension. I suppose you could treat a wall like this much like we do a plain, grouted, or reinforced conc. block wall, with f'm, rebar area, etc., but the thin, brittle shells would cause me some concern. I’ve never really seen a design procedure like this for clay tile. To start to get a handle on Mike’s 2:1 or the 3.5-4 span ration, look at ACI two way slab design or look at Roark’s plate formulas and ratios and then do something to factor in the triangular loading vs. uniform loading.

If you could excavate outside, and straighten those walls, you might try the following, but I offer no guarantees. Shore the wall every 3-4', and saw cut a 8-10" wide vert. slot in the wall, to a little less than the depth to the middle clay vert. web. Epoxy a threaded rod (A.B.) into the footing, maybe a coupler or a full height rod. The tops of the rods are threaded and have a 4x4" bearing pl., and a nut and washer, which ultimately get tensioned with the nut and washer, almost like post tensioning. The tile cells are plugged and the 10" slot is grouted full height, then the rods are tensioned.

 

[AELLC]

As far as design reference, I don't recall anything because I have never dealt with clay tile.

Perhaps James Amrhein's Design of Reinforced Clay and Concrete Masonry could help (I am not 100% certain that is exact title)

 

[a2mfk]

Step 1: run away
Step 2: tell anyone in the building to also run away
Step 3: thank any spiritual deity you may believe in for performing a miracle, which is the only explanation of why that wall has not failed

Maybe you can use that wall as a form for a new interior reinforced concrete wall. I may knock some ports in some of the cells to allow concrete to flow into them to provide compression reinforcement only so that the clay tile wall can transfer the soil stress into the new concrete wall. You will also have to add some connections for proper load transfer from the upper floors and walls.

Good luck with this one!

 

[TLHS]

Yeah, there's no way in hell that thing's spanning vertically. There's no particular mechanical connection between units as far as I can tell.

 

[mijowe]

build a second reinforced CMU wall adjacent to the interior face of the existing. Excavate the perimeter and waterproof and provide perimeter drainage.