Wedge Anchor OVERKILL or NOT? 2

[h2ohound]

This seems to be wedge anchor OVERKILL.
Currently erecting a 20’x51’6”x19’H Quonset hut.
Q-Hut manufacturer concrete design spec’s minimum 2500 PSI @28 Days.
Anchor bolt detail spec’s ½”x5.5” HILTI KB-TZ’s.
If concrete does not retain equal or greater value of anchor, why would design professional spec HILTI verses say, RED HEAD with similar strength value to concrete?
Not a state or government project, home owner garage.
I just don’t get it. Cost difference I do get.
Same project drawing spec’s 6”x6” W.W.R. in slab, only rebar spec’d schedule 40 18”oc stubbed out of footing 2’ into slab.
I always use grade 60 because I can buy for same price as grade 40. Rebar is obviously more costly than W.W.R... In my opinion, w.w.r. doesn’t do anything anyway. Always ends up mashed down below concrete pour.
This just doesn’t make sense to me.


Busy Building,
H2ohound

 

[JedClampett]

Just a guess, but I know that a Hilti TZ is code compliant and Red Head only did the testing recently and only for the TruBolt Seismic.
Even garages need to follow the building code. But if you get a 90 mph gale, leave the house and go to your Quonset hut.

 

[racookpe1978]

Schedule 40 rebar?

 

[FSS]

Grade 40 is pretty common in residential construction. Check the grade for what you get at Lowes/Home Depot. Not everything out there is 4000 psi concrete and Grade 60 rebar....

 

[ztengguy]

anchor type and concrete strength don't always correlate. Perhaps they assume a certain edge distance, bolt spacing, etc. Kwik Bolt TZ is also only anchor I know approved for cracked concrete. Obviously they had a competent engineer work on this.

As for the rebar, Grade 60 would be fine. As for WWR being mashed down, then you need to get a competent installer that will chair up the mesh to where it needs to be and not mash it down.

If you want cheap, go cheap. If you want it done right, sometimes it costs a bit more.

 

[paddingtongreen]

Why the question? What is the cost benefit of the question?

How much will you save by making the change versus the cost of the time spent negotiating the change and the faffing around before the negotiation to collect the information.

Be grateful that they gave you a design. change it and you take on the responsibility for the design.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin

 

[cliff234]

We always require post-installed anchors to be compliant with ACI 318, Appendix "D". Most of our projects are in locations where we are required to follow the IBC Code. IBC requires that post-installed anchors be designed per Appendix "D". I refer to non-Appendix "D" compliant anchors as "illegal anchors".

 

[msquared48]

"Hilti Profis" is a design program by Hilti that is compliant with Appendix D. Red Head does not have such a program. One would have to do the BS by hand.



Mike McCann
MMC Engineering

 

[oldrunner]

Well, Grade 40 steel is a lot easier to cut and bend than Grade 60. We quit using W.W.M 40 years ago or more. We use rigid mesh or bars and always on dobies.

Garages are open structures and can have sometimes a tendency to fly - especially if the doors are open in a very strong wind.