Through Bolts in concrete Structures 7

[dik]

Is there a good article on the design of 'through bolts' in concrete structures? For example, a bolt going through a concrete wall or column supporting a steel beam.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[desertfox]

Hi Dik

Try this:-

http://steel.fsv.cvut.cz/infaso/InFaSo_Design-manual_II_En.pdf

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[dik]

Thanks, fox... I'll take a look. There seems to be a general consensus that 3x bolt dia for length in bearing, and I'd allow the increase in bearing strength for the confined area of bearing, but nothing more than a concensus.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

On first glance, it seems to accommodate headed studs and not through bolts.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[desertfox]

Hi Dik

It mentions threaded rods in chapter 4.2.
I wasn’t aware of your definition of through bolts, through bolts in my line are just bolts that pass through several components to be clamped, we call bolts without a head a stud

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[robyengIT]

here a previous discussion

https://www.eng-tips.com/viewthread.cfm?qid=463957

and some suggestions on pages 40-41-42 of PDF file

https://mega.nz/#!1ZUgzCzA!bjmu5dnN_kwXuu9NgfdSti1uILWyyU-7WZ5KjsEMNSw

 

[dik]

fox... the through bolts in this case are bolts fitted through a hole drilled through the wall or column; they are not cast in, or grouted in. Thanks...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[KootK]

Summarizing my thoughts from the threads that have already been referenced:

1) The only literature guidance that I know of is the masonry stuff that slick deals mentioned. I question its validity for this because it's based on double shear load delivery.

2) If the holes won't be grouted, shear delivery can be expected to be uneven and require movement. Yuck.

3) In the past, I've had mentors tell me that, for shear delivery, these are really shear friction setups. I think that's made prohibitively complicated as follows:

a) You rarely have good control on the bolt pretension and;

b) Concrete creep tends to neuter the bolt pretension.

4) I'm of the mind that most things that might be done as through bolting are probably done as well or better with epoxy/expansion anchors. Yes, I know that we've been through bolting since time immemorial. That just makes it all the more sketchy that there's such a dearth of design guidance. Through bolting feels decent to me when the load is predominantly tension and it's basically backside punching shear on a plate. For shear transfer, however, all of the action will happen at the front of the bolts.

 

[desertfox]

No worries Dik

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[canwesteng]

Are through bolts acting in tension or in shear?

 

[dik]

They are acting in shear, only. The force is quite high and the EOR has spec'd six 7/8" ASTM F1554 Grade 55 through bolts. I don't think the connetion works, but I've asked for design loads.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JLNJ]

Your arrangement might be analogous to expansion anchors in shear only with side bolt bearing being the controlling case.

3x the bolt diameter for shear-only arrangements seems too generous.

 

[dik]

That's what I'm trying to find out... I think a length of bearing equal to 3x the diameter is pretty stiff flexurally and don't think it is too generous... The actual strength,other than shear failure of the threaded part will likely be a tension failure of the threaded rod as it tries to pull out with whatever deformation occurs prior to that point and other than locally, I don't see the concrete crushing, but I don't know.

You'd think that for something as common as this, there would be a common procedure, too.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

Still no closer to an answer on this problem.

Looking at shear friction, it appears there is no part of shear friction that addresses concrete strength (as is bearing). All parts seem to include both steel and concrete. Is there a portion of shear friction that addresses bearing only?

The actual strength of the through bolts in shear and/or tension is more than sufficient. It's the bearing part that is a problem. For the steel to fail, it must pull through the concrete with the plate washer; that will not happen. The alternative is the concrete crushes, but I cannot find reference to that in shear friction.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[desertfox]

Hi Dik

Does this help :-

https://mechguru.com/machine-design...oncrete-breakout-strength-of-anchor-in-shear/

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[dik]

Thanks... I'll take a gander and see what the numbers are like; it's another approach. My condition is an existing concrete column with six 7/8" diameter through bolts with square washers on the back face securing a large steel plate on the front. The contractor has to drill through the column to install them, making sure no rebar is cut. There is no reference to grout. The beam connecting to the front plate with welded clip angles. The load is about 65K factored.

Using Hilti Profis, using HAS E-55, the connection has less than half the capacity in needs. The Hilti is a proposed change by the contractor. I can easily bounce it back for the EOR to confirm the connection is adequate. I'm just trying to confirm, to myself, that it is OK. The bolt capacity in shear and tension is lots... (The last item should read "Maximum Tension Resistance" and not 'Shear'...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Celt83]

Through bolts in single side shear I would treat as normal anchors with an embedment = the member depth. The mechanism for shear resistance for a single side loaded through bolt vs cast-in or epoxy anchor is the same if not potentially worse since there is no bond in the through bolt scenario.

Through bolts in pure tension I can get behind a punching check for capacity.

 

[dik]

Thanks Celt... my main query is that HAS E-55 only provides half the load capacity; I'd have thought the value would be higher. I don't own the EOR's design; I just want to be comfortable with it... I'll take a look at it as a headed stud with a large head and length...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Celt83]

dik:
I could see an engineering judgement path to side step a concrete pryout failure mechanism with a through bolt, so only check steel failure or breakout failure. I've seen judgement made that the column base isn't a free edge so breakout is restrained by bearing of the failure cone against the column/slab/foundation below, this doesn't satisfy the ACI check for parallel edge condition.

 

[dik]

Thanks Celt... and there's a pile of reinforcing in the column... dunno how much, but it will contain them.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik