Simpson H2.5A - Installation Approval Question

[dhoward26]

I recently took on a project for a contractor designing a 2 story ICF custom home. I spec'd out H4 clips from truss to sill plate. Here is what the contractor said:

"we have used single top plate on top of the icf walls with h2.5a for every project, and only get 3 tico nails in the plate, which has always passed inspection and been signed off by our engineer."

Am I missing something here? I have always required my contractors to install per Simpson requirements. It seams this contractors engineer is knowingly putting both of them at risk for some major legal issues in the future isn't he?

This is also the same engineer that said a vertical #5 bar in the stem of a retaining wall only needs 11" vertical embedment into the footing (without a 90deg hook) to develop it's strength. I'm assuming there are many basement retaining walls out there right now that don't have the required hooked bar that most of us use.

 

[woodman88]

For some uplift it may be okay. But the lateral forces, especially perpendicular to the wall, fall to nil in my opinion. So it really depends on how much force you have and what else is being done to transfer the forces.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[Ron]

dhoward26....stick to your guns. The other engineer might be winging it.

Even if inspected and approved by a municipal inspector, it does not relieve you of your responsibility.

In most cases, ALL holes in the connector must be filled with nails.

 

[dhoward26]

I'm sticking to my guns with it for sure. If they ever had a major failure in that location with their other homes they would be hung out to dry. Good luck winning the argument in court for not installing per Simpson's recommendations. To me it's a bit scary that people approve improper uses of a connector.

The other concern I have is they've been building 10ft tall basement/retaining walls with 15" thick footings and this other engineer has been running the stem reinforcement with only an 11" embed into the footing and no hook to develop the bars. None of my 4 text books recommend this as a design procedure...neither does the "Basics of Retaining Wall Design" book.

 

[hokie66]

Are these cantilevered retaining walls or basement walls braced at the top? You said the footings are 15" thick, but how wide are they? If the walls are not assumed to be moment connected to the footing at the base, development of the reinforcement would not be necessary.

 

[dhoward26]

They have done both braced and unbraced. Footings ranged from 4.5' to 7.5' wide. The contractor sent me some of the drawings so I could get a feel for what they are used to working with.

 

[dhoward26]

To clarify...both cantilever and braced basement walls.

 

[hokie66]

With a footing that big, I would automatically assume it is resisting overturning, thus the retaining wall bars have to be developed to be effective. Either the contractor is lying or the other engineer is incompetent. You have to wonder why anyone would resist using a cogged (hooked) bar for the starters, as straight bars are hellishly difficult to hold in place without the horizontal leg to tie to the footing reinforcement. Maybe the contractor is used to "sticking" the bars, which would be another indication that he is shoddy.

 

[dhoward26]

I agree. Even with a basement wall that is braced top and bottom (and supporting about 5000plf of load), I still hook my bars as there is ultimately going to be "some" bending action in the toe and heel as there truly isn't a pin-pin connection.

I looked at the drawings, and they show 11" embed of stem footing with no hook. I was shocked. A #5 bar develops in about 11" in compression according to code. Makes me wonder where this engineer learned to design retaining walls...design in general from what I have seen.

 

[charliealphabravo]

Simpson tech support is very accessible for questions like this about alternate installations.

I have allowed contractors to deviate from the Simpson requirements but only if they follow my job-specific installation detail located on the plans. I have also done this when using a Simpson component as part of a more complicated connection detail. Basically it is no longer a Simpson connector at that point and performs according to your rational analysis.

In your case I would just have them use the connector per the manufacturer or perhaps give them an option to use a different Simpson connector.

 

[Teguci]

For 8,000 psi concrete, I get the development length of a #5 down to 12" prescribed minimum. Even calculated (ignoring the 12" min), anything less than 6,000 psi concrete requires more than 11" (best case ldh calc). Also, for cantilevered retaining walls only, per 12.10.3, d is the min embedment (13" for a 15" wall).

Now that you know, and, if you are licensed, you must act.

Why wouldn't you use hooks? I would think the contractor would ask to use hooks just for ease of placement. Of course I caught one of my contractors pushing straight bar into the ground for placement of the cantilevered wall reinforcement. Pointed to the detail where I had clearly called out "Hook" and the dims. The two striaght bars coming together at a 90 deg angle wouldn't cut it.

 

[dhoward26]

Teguci:

Thank you for the info. Something that I just found in ACI 322

Subject to local approval; according to ACI 332-04 “Requirements for Residential Concrete Construction”, section 6.3.4.1 “…to facilitate positioning
before concrete placement, vertical dowels are permitted to be driven into the grade in the bottom of the footing.”

Interesting, I had no idea.