Vertical Crank in Suspended Slab

[SteynvW]

Does anyone have a reference for when it is permissible not
to have special detailing at a vertical crank in a slab?

My slope is 1:18 and detailing it like a big change in angle feels like a waste.

 

[Lomarandil]

I haven't heard of a reference, but perhaps when the splitting force across the joint is less than the tensile strength of concrete is one limit?

Similar to the procedure for checking the connection between a flight of stairs and landing.

----
just call me Lo.

 

[KootK]

The standards manual of one of my former employers used to say that you were okay up to 4% difference in slopes. So close...

Not that there was any science to it as far as I know.

 

[dik]

One of my old concrete consulting employers used 3% and for more than that, bars were anchored on each side of the 'crank' to prevent rebar tension uplift from popping out the concrete.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[Tomfh]

If there’s any question then I’d carry the tension bars through and lap with bottom bars.

 

[SteynvW]

My intuition is that it will be fine, but the structure has 100 year design life.
So I guess since there is no solid literature to back it I will have to continue it through
at the angle to splice with the respective bottom and top bars.

Thank you all for your input.

 

[KootK]

1) Franky, I struggle to find any decent theoretical justification for bending bars around reentrant corners at any angle. That, particularly when you consider that the radius of the bar bends means that you probably have less cover at the knuckle than you do in general.

2) People are fond of pointing to the various "percentage rules" as having been tried and true over many projects and many years. My suspicion is that a lot of these situations are greatly helped by the fact that, often, the sloping slabs will have in plane restraint coming from somewhere which will tend to change the situation substantially.

3) I don't actually understand the economic argument for bending the bars in many cases. For the situation shown below, would have thought it would be easier to just run the bars through as shown than to install a bunch of bar custom bent to suite the angle. Can anybody shed some light on the economics? I suppose that bending the bars would be a fair bit easier at a two way top mat if that's the situation.