Guardrail post to deck slab through-bolted connection design

[JSAR]

Hello engineers,
I have a cane detection rail post (27" height) that requires to be connected to a concrete deck slab which is 5" THK (2" deck + 3" concrete). Expansion or chemical anchor (HILTI) connection didn't work & was even rejected by the SER. So I was wondering if I could go for a through-bolted connection (refer to the attachment).
Following are the checks which I could perform for this connection (ACI 318-19)
1) Tension
1. a) Tensile strength of the bolt
1. b) Concrete breakout strength in tension
2) Shear
2. a) Shear strength of the bolt
2. b) Concrete breakout strength in Shear
3) Concrete pryout resistance
4) Interaction- Tension & shear
5) Concrete block compression resistance check
6) Plate flexural strength
Note: There wouldn't be any edge breakout as the edge distance from the post center to concrete edge is definitely more than 10'-0"
Could someone please advise if I am missing anything or required to perform any other checks and the necessity of the above checks?
Just need to be sure that I am approaching the right way to design this connection. Thanks in advance.

 

[Tmoose]

"Expansion or chemical anchor (HILTI) connection didn't work ..."

How did those anchors not "work" ?

Were there just 2 anchors per post, and located as shown in the attached pdf at the rail post centerline?
Is the direction of Vu as shown, relative to the anchors ?

 

[dold]

What sort of load is required for a cane rail? It looks like youre using guard rail 200lb/50plf. I'm not sure I'd consider it a guard rail. They're typically just underneath stairs without any opening. I.e., ground floor. If EOR says you have to use guardrail forces then you should use 4 anchors. And you can direct angry comments from architect to the EOR. Did you ask the EOR what sort of connection they would approve?

Anyway, I'd be very surprised if you had any issues getting 3/4" A325 bolts to work out . If you can't convince the EOR to relax and you go with this detail, I'd have them drypack grout between the bottom plate and the soffit of the deck in case there are overhangs like you're showing. Or just use a bigger plate that guarantees coverage for any location.

I'd check shear in the slab. That's about 8.6k-in/2"(ish) / 7" =~600 lb per inch? phiVc = ~250 lb per inch? Might be a no go? Unless I totally botched that. Or look at 2 way shear. Or consider the deck.

 

[dik]

Can you use four 1/4" dia x 2" long tapcons. Rough guess BAR 3/8"x4x4 baseplate and edge dist of 3/4"? and conc strength 25 MPa? Throw a layer of WWF at the post locations... centre mesh so it misses the tapcons?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[JSAR]

@Tmoose, Yes, expansion or chemical anchors didn’t work as the concrete depth is just 3” @ deck flanges. I ran the arrangement in Profis & it won’t design for due to insufficient depth (min.=4”).

@dold, You are right. Technically, I feel the cane detection rails doesn’t need to be designed for 200#. So, I went through NAAMM, AISC design guide-34, ASCE7-10, IBC-2015, ANSI 117.1 & even ADA. There isn’t a solid recommendation or suggestion from any of these codes regarding the loads to be considered for design of cane detection railing. All these codes recommend the 200# for design of railings at stairway/ramp/aisles/equipment/walkway/platform.

@dik, I don’t think WWF at post locations is a possible option & not sure if SER might approve.

However, SER & ARCH suggested for directly core drilling the post into the concrete deck slab (max depth=2 ½”)-Refer attached snap. When I checked for embedment depth the minimum required would be 4 3/4"(fc’= 4000 psi). I don’t think embedding the post would work.
I could propose the EOR w/ 4~3/4” Ø A325 through-bolts even. The reason I didn’t go for 4 bolts previously is that it might be a trip hazard especially for visually impaired coming closer to this rail.
I would really appreciate your thoughts on any other way of connecting the post to deck slab or if through bolting connection would suffice…

 

[XR250]

3/4" A325 seems like super overkill for this

 

[Ron]

If the slab is susceptible to weather exposure, you'll need to consider waterproofing if you go with through-bolts.