Flat arch tile floors

Just don't stand underneath!

Do these stick out 20' !!??

It sounds a nightmare, do you mean the overhanging horizontal beams have 'tension' bars near the lower edge? This would surely be in compression..I'd expect a tension bar to be center or above.

I probably don't know what I'm on about...but I'd certainly back you on this one!

Sounds like they need screw jacks under them and some serious re-work.

Blimey, that's why I'm glad I'm in electroics... If I screw up I can rebuild in a few minutes!

Good luck

Del

yhet "stick out" 4 ft, spanning 20 ft. The tension rod is at the bottom because that is the area that would "open" tp allow deflection. The tension rods apply a super-compression to cause friction between the butting faces. Clay tile floors are usually mortared, but these are not.

FEMA has a report on one of the ancillary masonry buildings adjacent the World Trade Center, circa 1920 that has tile arch floors and was struck by a large piece of the tower during the collapse. The tile floors performed far better than a nearby steel and concrete building struck by a similar size piece.

And I don't want anyone under, or ON, the balconies if I can avoid it. It may be for low income tenants, but I still want them and their children safe, even after I am gone.

RichH

I'm not an civil engineer, but don't take short cuts. Sack the engineer if your not happy. Sounds like a cowboy. You are allowed to disagree but he has to prove why he is right and you are wrong. Do you really want to risk the life of someone you responible for? Would you let your kids play there? Spent the extra cash, rent it out to a high paying tenents, claim it back on tax do anything but put people's lives in danger. If you do a dodgy job now, it won't matter that you sell it, if anything happens (god forbid) and someone is hurt or dies. YOU will be responible. If you get sued or sent to prison for manslaughter it's your own fault. Do you really want the worry at night?

Sorry to sound harsh and you are doing the right thing by worrying but you should be very, very worried.

good luck. Hope someone can post you the technical expertise for your problem.

here's some gifs. This is the worst to be replaced with a wood balcony. Someone has added fascia to hide the front edge separation on the other 7. This one the fascia bent and fell off. The others are merely bent.

Thanks,

RichH

Thats just plain scary. These are purely cantilevered balconies, or are there posts or tiebacks or anything? When you mentioned arches, where are they?

The arch is flat. Many industrial floors have been constructed with flat arch floors. The tile (in this case, block) are held in compression by threaded tension rods, usually with a Rose nut outside of the wall, usually through a channel, and the tension rod is never grouted, as these have been. Even with floors, corrosion of the rods from poor or a lack of maintenance is the biggest problem.

That looks awfull...

RUN!

I don't know that running would even help me. Someone else would take it over, and then someone gets hurt, and I still would feel responsible. I think I'll stay and take my stand, and if politics sacks me, it won't be the first time.

I've never had a "sponsor", and don't want one now. Twice, I've been fired, and told them I agreed, but I'd leave in six months. I got by with it both times. If I have to, I can do it again. It sure beats a couple of weeks severance. Politics can't bite you when you're honest, and right.

RichH

Those photos really show how it works (or should work)

I originally thought the rods were coming out from the building in cantillever beams(hence my assertion that they should be on the top edge)

I can see they are along the length of the balcony now.

The whole thing is like those block jugglers who hold a row off blocks horizontally by pressing the two ends together...then toss 'em in the air and catch 'em again.

From a semantics viewpoint I'm a tad conused where the 'arch' comes in...I see no arch (maybe the 'arch'-itect has it?)

I would suggest this approach.... Install I beams

Or remove the balconies completely..

The problem with edge support would be that you would need one at the building edge, too. the 4 ft balcony is 3 rows of 16 inch block, and the block ends offer inter-row vertical support only and have no cross ties. I don't believe that there is any deck salvageable, only the lookouts if they are cleaned and painted. Removing the outboard decks is bad enough. The 4 inboard balconies are supported by pockets in the building structural wall.

For the outboard balconies I can only strongly recommend that the contractor shore up and deck the balconies before demo. If they ever get around to the inboard, I'll enfoce that as a structural threat to the building. How did they install and grout the rods there? Or was the brickie the general.

RichH

I thought about this too. Those rods you mentioned are under tension, and have stretched. If you are going to use structural steel, you will remove the load from the rods, and then the pressure applied between each block will be removed, and they will no longer form an arch. As you mention, there is no inter-row support, so you may as well start over.

Remove all the block. Retain the railings, and the I-beam stubs. Make some form of prefab balconies, (wood, prestressed concrete, or steel) and install to the I-beams, and then re-install the railings.

If this will blow your budget, maybe you can have the deck repairs re-appraised if you can, and separated from the initial contract.

Chris

Chris

The photos suggest that the 20' span is supported on each end by a 4' steel cantilevered support. The distress to the underside of the balcony "tile" and the deflection (positive moment) suggests that the tension reinforcement has yielded (maybe due to corrosion), or that the "tile" failed in compression.

I cannot harvest enough information from the posts or the photos to say that the original construction was fundamentally flawed, or to offer a reasonable solution. Appearances suggest that corrosion of the tension reinforcement (rebar) is the cause, perhaps salt or other corrosive deicer has caused this to develop more rapidly on some balconies rather than others.

I believe that your concerns are well founded and that catastrophic failure is possible. Someone could be killed if on of these fell. Repairing those that exhibit deflection is a must. It is reasonable to believe that the construction in one balcony is representative of others, therefore, a little investigation is warranted to evaluate the performance of the others. I anticipate that they all would warrant similar repairs.

I agree, but I also would like to find design or manufacturers data for flat arch construction. The vertical load capacity requires a post tension compression load from block to block. The tension member should not be subjected to any shear load, and should only carry a system tension and be free of localized stress.

The compressive load is required in a similar fashion to a loaded masonry wall. A wall with a 10 kip load is far more stable than a parapet wall with only a 200 psf load.

Tile arch floors are mortared, then compressed to permit the transfer of the vertical load to the supported end block. This structure appears to be designed dry set. The only transfer available is from the surface to surface friction, which requires a compressive load on the joints sufficient to prevent joint slipage.

the rebar could never supply the preload that the arch requires. Somewhere, the criteria for a stable arch nust be out there, hopefully on the web, but if in print only, I'll buy it. We work with many 100+ year old buildings, and I'm sure that it would be used again.

RichH

Unless things have really changed while I was sleeping, it's the architect who is primary liable. So it's not necessarily wise to assume the architect is a "cowboy" who will not appreciate the liability to himself. Better to ask for second opinions. If 12-year old (?) architect will not work with you, find a replacement. Doesn't hurt to ask any architect if he/she understands and is fully prepared to accept liability. Be sure to ask and check the architect's license and bonding. If he/she hesitates to provide the license, and insurance binder, find someone else.

I only inspect to assure that the public monies tn these projects is effectively spent, I review pay applications. In this case, the architect is on the board of the agency which now owns the building. I can't replace him, and the total reconstruction budget was less than $100,000, including 12 new vanities/sinks, kitchen counter tops, patching AC openings, new windows, and repairs, out of $10,000,000 purchase and development

I don't mind a battle with the kid, but I need some data to show my bosses that there is a larger problem than this kid is aware of. There are not a lot of people who are aware of what a flat arch is. Especially exterior block constructs. It took me a while to see them;

RichH

I see your new avatar. How high was your SAT math?

RichH

LOL!

I'm fine working in nibbles!

This problem could really use a photo... Maybe you could post one for us.. to better understand the issue. I worked as a junior draftsman, for an heritage architectural company years ago.. we used to place steel post and beam inside stone door and window settings as a matter of standard procedure.

Arches are inherently strong, but that does not mean that they have been applied perfectly in this building, or that the materials they were built with were sufficiently strong. There can be many variables leading to the breakdown of structures such as this.

I think it is time to call in the structural engineer. He will provide you with a comparison of the structural load bearing capacity of the existing construction and repairs, and also be able to put some numbers to any new methods of repair and adjustment you wish to simulate. If your architect does not appreciate the reality of what comes from that source, then you have little choice but to go political on him.

I believe you are the new general, but as you said you supply the fundings, so you may also be the client. If you are the client, then you have to authority to fire the Architect. If you are the general, you should still be able to present your case to the client, especially if you have consulted a structural engineer. There is no need to go into this fight unarmed. You can have real answers from a structural engineer in your area.. available in the yellow pages.. I don't think there is a substitute.. given the risk.

The architect, in a court of law, can blame the general contractor for shoddy workmanship, or choice of materials. or quality control issues, such as the wrong grade of concrete.. If you have the structural engineer aligned with you, and your materials and builders are certified, then you should be in a good position.

If that is not enough, then maybe ask the structural engineer for a 3D modelled analysis of the worst case scenario of the failure of these units. If that doesn't work, I'd fake a heart attack, and walk away from it all...lol

Best wishes,

PS. Keep your insurance paid up!

I represent and inspect (structurally) for the state as an employee of the Housing Development Authority, funding new or re construction of low income, senior, and/or special needs housing. I first learned about flat tile archs when I worked on a rehab of a 23 story industrial conversion to residential 28 years ago. No tradesmen at that time remembered working on one, and as Project Manager for the developer, I had to learn quickly. Thank goodness for some good old detailers. You remember them? Scary to think of the contractor who built this 35 years ago.

RichH

I'm not a Structural guy, but have some experience with renovations,
and those photos worry me.

You're dealing with politics here, and one thing I've found effective there is
to write a letter. - Go on record as having a concern. It puts the ball
squarely in the other court 'on the record` and not only covers your ass,
(a good idea in this situation), but forces them to re-evaluate their actions
on the basis of having been warned of a problem.
It's hard to criticize you for it officially, you're just doing your job.

Hi. My suggestion for the I-beams is maybe a waste of good steel and money, however if you are going to renovate it might be a good idea to demolish all the balconies, put two I beams in and on top of that a 4 " steel reinforced solid concrete slab in stead of this flat arch idea. A good reinforced concrete slab might not even need the I -beams. It is defenitely eighter that or no balconies at all.

If the top balcony fails the lower ones will most likely cascade. Very dangerous sitiation. Eventual failure is certain. Agree sag is due to yeilding of tension rod or block failure. I beam cantilever beams could be used as support for new prefab deck. look at standard catwalk decking construction for economical solution.

Demo all the balconies

The "flat arch" was never installed correctly

This is dangerous

as stated before they can save the railing and the structural steel cantilever beams and that is all!!

The inner decks could be supported with steel. Surely the cost of demo and rebulding the outer balconies can't be "too" high. Just build the decks from wood and secure each two story deck to the building. Stain the wood decks right and they will last long enough for the government to be happy. I am just postulating ideas.

The owner/architect believing that only the worst 1 needs to be demoed is the problem. My guess is that it will blow the budget by more than $100,000, And did I mention that the apartments are occupied?

RichH

The inner decks are fine as the load cannot spread them sideways and allow thenm to bow.

I think you are right with timber! Light & strong. A couple of pressed steel joists across the long face and good ol' timber.

They'll probably go with a 14 inche microlam front, and a ledger on the wall. Of course, that depends on what they find behind the decks.

RichH

I've read all the other replies and your further comments and photos. It doesn't look like an arched floor. I would suggest that it is a reinforced concrete floor and that the grouting of the rebar is probably a repair.

Arched floors do not have such a long span and the aspect ratio (depth to span) is not at all in keeping with an arched construction (1/20 is very shallow). It is actually beam construction? The pattern underneath the soffit is only decoration?

There appears to be quite alot of damage to the exposed balcony which puts it in peril of collapse.

A 1" deflection over 20' is only 1/240 (acceptable for a beam with no particular finishes) but is 1" to 4' = 1/48 for the central cantilever portion. The designer may have taken the wrong design criteria. The idea of jacking up the slab and putting a steel beam along the front (with appropriate dry packing) may well be the best and cheapest idea.

The fascia look as though they were always there to decorate the steel and concrete. A bit of extra fascia can't hurt?

You should get a second opinion from a structural engineer. Firstly to look at the typology and condition of all the balconies (none of the other balconies seem to have been physically looked at?). Secondly to check the interaction between the balconies and the main building as there might be implications (albeit unlikely).

It is not enough that someone says "trust me". They need to show why.

Flat arch tile floors were a staple of multistory construction from about 1900 to about 1920. They are built dead flat, in many cases the tile were trapezoidal in shape with a keystone piece, but more often were square tile, mortared, and then compressed with the threaded tension rods to create a lateral bond capable of transferring the load from block to block. The flexion of the deck caused the grouted rebar to bend, placing an internal stress in the cinder block, causing the faces to separate. The attached picture shos a pair of block faces hanging by the caulk a previous owner used to hide the cracks and allow painting.

Demolition verified the 8" X 8" X 16" cement block with a 3" topping. The odd feature of the block were the holes through the webs for the tension rod, which was supposed to supercompress the joints for friction support.

RichH