Concrete anchor edge dist 1

[MNach]

I am using HDA-T anchors (4.9” embed roughly) and they are going into a concrete arched beam (16” wide, 3’+ deep). The ceiling is also concrete (integral with beam). Being conservative, I am using an edge distance of 5”, but I am pushing the capacities of these anchors above their limits doing so. Do you see any issues with not using 5” as an edge distance here? Does anyone have any recommendations on determining the actual capacities of the anchors in this situation? The cone of failure would make a full circle, the concrete can’t exactly blow out on the side since there is also concrete there. I feel as though this reduced section at the ceiling may have some effect but not as much as calling it an the edge of the concrete would.

***anchors are not drawn to scale

 

[skeletron]

What's the reinforcing situation around the anchors? Can you take advantage of that to confine the blow-out? It sounds like you want to rationalize a solution based on your situation. Draw in the failure cones for each failure mode. Make a decision that way.

 

[MNach]

There is rebar everywhere in this and I am currently using it to help resist shear and tension. The individual capacities are not exceeded, it is the combination of the tension and shear that pushes it over capacity.

That's the thing, when I draw the cones, any breakout due to the tension has a fully developed cone within concrete. When the shear breakout cone is drawn only part of the cone (roughly the top half) can actually break out, but I am not aware of anything in the code to quantify that.

 

[Agent666]

Which way is the shear going?

 

[MNach]

There is a very small amount perpendicular to that edge face. The bulk of the shear runs parallel to the beam. The beam is arched and we are connecting at an angle do to the arch. The tension acts vertically, but due to the arch angle it is causing a shear load.

 

[Agent666]

My interpretation is for the tension, if the breakout surface isn't impacted by the slab/beam edge interface, then there is no reduction due to the edge. Usually this is 1.5xanchor effective depth spread (35 degrees there abouts).

For shear parallel to the beam, for concrete breakout you have a large edge distance in the direction parallel (some of the breakout surface is the beam depth and some the slab depth) and similarly large distance perpendicular (presumably to the next beam). Therefore concrete breakout is unlikely to govern unless you are right at the end of the beam or edge of the slab.

Another failure mode such as the steel anchor capacity or pryout will govern (this is a function of the concrete breakout capacity in tension). Therefore for you scenario I don't believe the edge of the beam really factors into the governing failure mode.

 

[Bagman2524]

Agree with Agent666. I don't see any edge distance affect on the failure modes.

All I know is P/A and Mc/I