Strut & Tie model short pedestal 2

[mte12]

Can anyone share their model for designing a short pedestal for strut and tie actions.
Of interest is the development of the tension tie, at top node, for shear load.

Let's say pedestal height is at limit between flexural/strut and tie action, say 1.5.
If H/B > 1.5 (flexural), tension at top approaches zero.
If H/B = 1.4 say, tension at node 1 is relatively high. So not a smooth transition.
For pilecaps, common method is to have sufficient development past the node. So presume sufficient length below node 1 is required??? Or is total vertical length allowed for? Or do you allow contribution from cog other end? But latter doesn't seem correct unless radius of curvature is high (10 x bar dia).

 

[HTURKAK]

You can adopt the rules for the corbel designs. In your case , the corbel is slender and needs to be modelled with multi diagonal ( C ) elements.
The following figure from ( Fingerloos, F. and Stenzel, G. Konstruktion und Bemessung von Details nach DIN 1045. In: Beton-Kalender 2007 )

 

[bugbus]

Disagree that tension at the top would be zero in any situation.

Even for a long cantilever with a point load at the tip, the end of the cantilever is still a D-region and there is an immediate demand on the reinforcement at that point.

 

[mte12]

Thanks for comments guys.

I was looking into corbels after posting.

Did see this diagram in ACI 318M-19. Haven't determined yet if development is required at both side of the node though.

 

[mte12]

It looks like anchorage for tension tie is by welding to anchor bar into the page or horizontal loops.

Section shown says:
... An end hook in the vertical plane, with the minimum diameter bend, is not totally effective because a zone of unreinforced concrete beneath the point of loading will exist for loads applied close to the end of the bracket or corbel.

Assume a tie continued as shown is not effective for corbels

What about for short pedestals, would you consider it as acceptable?

 

[HTURKAK]

What about for short pedestals, would you consider it as acceptable?

In case of short pedestals , in general the shear is applied with a base plate . The common practice is the use of hooks and ties /closed stirrups at the top of pedestal.

The use of welded transversal bar could be reasonable for the conditions described at 16.5.6.3.

Pls provide a sketch showing how the shear force applied to the pedestal to get better responds.

The following figure from PIP STE05121.