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TXStructural, Sorry about the cross-posting. It was a mistake rather something intentional. Thanks, too, for your input. Hokie, thanks for your summation. It certainly is starting to dawn on me quite how many compromises have to be stuck.

i'd take the full triangular masonry load & add a "line" load for the slab only.

thanks Hokie66, i appreciate your input.

thanks very much for all your responses. Unfortunately, the only slab like this in South Africa was only cast in Nov last year. Not enough of a track record to give me comfort. I have been doing a lot of reading around the topic though: The stock response to adding steel fibre into concrete...

I am investigating a proposal by a European supplier to use shrinkage compensating agents in a slab on-grade. Their claim is that by countering the shrinkage of the concrete together with the use of steel fibre-reinforcement, much thinner slabs can be used. While the savings all-round are very...

We are looking to advise a client regarding a largish (10,000m2) slab on grade. While we have investigated a slab with saw-cut joints at regular (close) centers, the client has also had us investigate SFRC (steel fibre reinforced concrete). One of the contractors is proposing the use of a...

I am working in South Africa and at a local project have proposed "clamping" on in-situ cast concrete “corbels” on both sides of an existing bridge pier in order to allow temporary jacks to lift the bridge beams for bearing replacement. My concept is for the contractor to cast the new corbels...

Hi Slickdeals I did search the formum before posting my question, but continued with my post as I wasn't 100% clear. The one thread seem to conclude that flexural reinforcing could be used as shear friction reinforcing. Would this mean, hypothetically, that if there was a cold joint, that I...

I am working in South Africa and struggling to reconcile the difference in shear force capacity that I get when i run 2 different calculation streams. Our SA code doesn't have a section on shear friction, but I have a copy of the shear friction section from an old ACI code which, with minor...

thanks to both of you for your help

I'm helping a geotechnical colleague in South Africa to calculate the shear capacity for different piles. The SA code doesn't give guidance on the calculation of Vc for circular columnns. My understanding is that ACI does. Can someone please help by posting the appropriate formula. Thanks in...

Does anyone have a handy bond stress value (or reference) for a steel dowel into the end grain of hardwood timber

Rapt, Thanks for your patient reply. No, I wasn't suggesting that you could use the PT on "both sides of the equation". But that by using it on the load side, it provided a simpler way of solving 2 way spanning slabs with odd support conditions. And Mu is simply provided with bonded "normal"...

Rapt Thanks for your detailed answer. But I'm unsure that I'm getting the my point accross. If you consider the simplest of harped tendon profiles, then each change of angle produces a vertical load, some up some down. Across the length of the profile these forces total zero. So there is no...

I strongly recommend that you get the water table data in writing so that you can base your design off information that is solid. Else make a "water table at the top of the tank" assumption and do the design.

Rapt Thanks for your reply. About 10 yrs ago I contributed to a course on PT run by a local polytech here in South Africa. In reading around the subject, I was astounded at the number of texts that were flawed in that they were prescribing calculations that made assumptions of section...

Rapt Help me out here. Why can't you use unbonded prestress for partially prestressed slabs. And why the need to do away with banded and unbanded? I would see the design procedure as follows: 1. Determine a practical layout for the unbonded tendons (the banded will then produce high upward...

Rapt & Hokie Thanks for your on-going input. With the Atlantic sea a mere 100m away from this project keeping things moderate I'd say a 30degree C range is probably what we're looking at. For a 70m building this implies around 30mm change in length. It could be that it would be better to...

I agree that the banded in one direct with unbanded in the other is a practical way of avoiding the congestion you would have with banded in both directions. the section typically are so small, any loss in cable height leads to a big change in vertical component of the cable force. But I can't...

hokie thanks for your additional comments. The bulding is in Cape Town, South Africa. Not as big a variation in temp as you might have experience with. But I get your point about the total only been made up of a part of the post tensioning effects. Current thinking here is that we will...