Column vertical reinforcement resist cone pull out
Column vertical reinforcement resist cone pull out
(OP)
Hi there,
I have a chemset connection into a compression column with dense vertical reinforcement. The connection is a shear connection however tension arises from a small moment on the connection due to the stiffness of the column v the chemsets. The chemists will be developed 300mm into the centre of the column.
Just trying to convince myself (or otherwise) that concrete pull out failure mechanism can be resisted by the vertical steel reinforcement.
Unfortunately the existing structural drawings are insufficient to determine the presence of ligatures that could be used in tension to resist this tension pull out failure mode.
If the vertical bars are sufficiently developed in this region, am I able to take the tension resistance of the concrete cone as equal to the shear capacity of this vertical column steel that is encased in the concrete cone (1.5hef from the anchor centreline)?
Thanks.
I have a chemset connection into a compression column with dense vertical reinforcement. The connection is a shear connection however tension arises from a small moment on the connection due to the stiffness of the column v the chemsets. The chemists will be developed 300mm into the centre of the column.
Just trying to convince myself (or otherwise) that concrete pull out failure mechanism can be resisted by the vertical steel reinforcement.
Unfortunately the existing structural drawings are insufficient to determine the presence of ligatures that could be used in tension to resist this tension pull out failure mode.
If the vertical bars are sufficiently developed in this region, am I able to take the tension resistance of the concrete cone as equal to the shear capacity of this vertical column steel that is encased in the concrete cone (1.5hef from the anchor centreline)?
Thanks.






RE: Column vertical reinforcement resist cone pull out
If you were using wedge or other mechanical anchors that fail in a shear cone, then wherever the rebar intersects the shear cone, there is positive influence on the failure.
RE: Column vertical reinforcement resist cone pull out
Thank you for your reply.
I am using the Hilti Profis software and concrete cone failure governs when I alter my edge distance, hence my identification that this is the critical failure mode. I don't think a 200mm edge distance with 4 36mm diameter bars hurting through it is really 200mm of concrete in terms of concrete cone failure in tension.
Splitting is not governing.
Thanks.
RE: Column vertical reinforcement resist cone pull out
I have not used the Hilti software much, but I'm still not convinced you should be getting a cone failure mode....even Hilti shows that adhesive anchors do not fail with cone shear.
RE: Column vertical reinforcement resist cone pull out
1) Satisfying appendix D provisions (Hilti Profis).
2) Using manufacturer's test data as evidence of performance. This should include criteria for edge distances etc.
3) Using reinforced concrete theory. Stuff like AISC design guide #1 or Widianto's strut and tie method.
If you're going to make use of the existing vertical steel, 300 mm sounds a little short to me. If you went with the AISC method, for example, you'd be looking to develop the vertical steel for your tension force on both sides of the tension breakout cone.
Do you have plenty of capacity with regard to shear breakout? If you post a sketch showing the particulars of your situation, I'd be happy to take a closer look.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Column vertical reinforcement resist cone pull out
Sketch attached. Excuse how rubbish it is - I am off work with a hand injury currently!
Top shows plan of column: vertical reo is max 75mm from centreline of the anchors.
Bottom shows elevation of column.
The profits software is giving me sufficient capacity for shear break out with the 230mm edge distance shown, and the edge distance above and below the anchor is infinite as its a column part way up a building.
RE: Column vertical reinforcement resist cone pull out
Could you rationalize a lower moment somehow? It seems extreme but, if you had to, you might be able to install through bolts and an anchor plate for the top bolts to mobilize the shear capacity of the section.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Column vertical reinforcement resist cone pull out
What is the expression for the additional capacity for the rebar crossing the tryout plane? And Appendix D of what resource? Sorry I am not familiar.
Thanks.
RE: Column vertical reinforcement resist cone pull out
RE: Column vertical reinforcement resist cone pull out
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Column vertical reinforcement resist cone pull out
RE: Column vertical reinforcement resist cone pull out
You need to look again. His plan and elevation both show vertical column bars, but no ties.
kynto3,
May be just me, but I would say your concern is unfounded. If it is a shear connection, why worry about a bit of relaxation in the fasteners?
RE: Column vertical reinforcement resist cone pull out
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.