Inspections, Testing, and when they need to be completed 1

[JohnnnyBoy]

I am a junior engineer with multiple more senior engineers in the office who all seem to slightly disagree about inspections and when/if they should be done along with testing. This thread is more an opinion on what and when certain things should be required by the structural engineer of the project.

- Pile Cage Reinforcement

My firm does not typically do pile cage inspection, is this wrong and should always be completed?

- Grade Beam and Slab Reinforcement

My firm always completed these for most commercial projects as a requirement, for residential/small project where we do not need to submit compliance letter we typically do not.

- Concrete Testing

My firm does not normally require concrete testing although we do normally ask it be part of the contractors QA/QC and we typically analyses the results for structural slabs and beams. Should this be part of our QA/QC and ensure that all structural elements always be tested, as we would easily get backlash from clients.

The reason I ask this question now is because recently concrete test results came back as part of the contractors scope for a structural slab and it failed, we have also had it fail on a slab on grade (less important but still a failure). We did not ask for testing on the piles, gradebeam or a certain section of beams although my concern is they may also be less than specified.

I would love to hear your thoughts.

 

[oldestguy]

With any part of the job, such as plans, construction phases, documenting the work done, etc. the legal ramifications can be many. Even though it may seem that some duties or other parts of the work may not be specifically spelled out in contracts, it is amazing how the lawyers will bring every one possible party into the fight. Then, what is really troubling, one party of the fight maybe almost clear, they may get stuck with much of the cost due to insurance, etc. That's the Deep Pocket situation. So missing some inspections or tests may not seem important, but once the fight starts you have no friends. So keeping mine the crazy way thing sometimes go, do our best for getting a quality job and no problems later.

 

[darthsoilsguy2]

In USA it is difficult to truly delete the testing of concrete. ACI 301 structural concrete has by its own definitions a minimum testing regimen. Even if you delete the testing scope from the specs and any notes on the plans, it is still there by any reference made to ACI 301. i think inspection is much more important that testing on any individual project, but routine testing is tide that raises all boat by increasing the overall quality of batched concrete for society in general. i've been working with concrete testing/inspection for about 2 decades and i wouldn't pay for strength testing for my own basement walls if i were building a house as long as it came in a truck... but i would inspect the H**L out of them before/during/after the pour and the waterproofing/drain too....

 

[Ron]

I offer a slightly different perspective...

First, testing of concrete needs to be done. I've been involved in consulting and testing of concrete for much of my 40 year career thus far. I've seen significant variability in the concrete that ends up on the structure....some of the variability is in the batching and delivery, some of the variability is created by the placement crews and finishing crews, and some of the variability is created by the weather/environment. Testing is intended to show that you got what you specified, not what ultimately ends up in the structure. If you don't know if you got what you specified, how can you possibly predict its performance in place.

Secondly, testing should be specified by the responsible engineer and/or architect. Generally concrete is a structural material in some respect, so the structural engineer of record should specify the concrete and the testing of the concrete for verification of the design intent. To do less than this is a violation of the standard of care, which puts the engineer into a higher liability position.

I have seen many, many structural engineers who do not understand even the basics of concrete technology. This is a travesty in my opinion. They need to understand the interaction between aggregate size and cement content, between cement content and its effect on water demand and shrinkage, and to understand that designing for strength alone can seriously compromise durability and long-term performance of the concrete.

Third, in my opinion, testing should never be part of the contractors QC program. Testing should be paid for by the owner as part of an overall quality assurance/quality verification process.

Next, testing should not be a commodity process. In a properly functioning QA system, testing should be done by qualified technicians with appropriate training and certifications. Testing labs have become such cheap commodities over the past 20 years or so because they have yielded to bidding for work, not educating owners and contractors that selection should be qualifications based, not price based.

So to comment on the OP's original premises.....yes testing should be done and it should be specified by your firm and the design parameter results demanded.

 

[JedClampett]

JohnnyBoy, I don't know if you're familiar with Chapter 17 of IBC, but if you're not inspecting (or having the owner or his designee) inspect reinforcing, you're not following the law (code). This assumes you're under the auspices of IBC and Chapter 17 hasn't been deleted in your jurisdiction. They also require that the owner, their designee or the design engineer observe the taking of concrete cylinders, which pretty strongly suggests that testing of the concrete is required. The contractor can do the testing, but you have to make sure the cylinders are taken of the correct mix.
I'm sure everyone has a story, but here's one I'm familiar with. Big project was going well, until they took a cylinder of a pour for some structure. It didn't reach 4000 psi, wasn't going to reach 4000 psi and wasn't close. The contractor shrugged their shoulders, said "we didn't do anything different!" After some investigation, it turned out that the batch plant reversed the proportions of fly ash and cement that day. The concrete had to be taken out, at the batch plants expense. But what would have happened if their wasn't a cylinder taken? Likely a failure, with no record of what happened. It's much easier to fix during construction than afterwards, not to mention loss of use or life.

 

[dik]

This is the 'big' one:

"Third, in my opinion, testing should never be part of the contractors QC program. Testing should be paid for by the owner as part of an overall quality assurance/quality verification process."

Even now, we often see that testing is carried as part of a 'cash allowance'... and, it is often that I have no control over this.

Dik

 

[JohnnnyBoy]

Thanks all for you opinions, It seems like everyone agrees that testing should be completed as required as part of our design requirements and results analysed compared to design. I do believe A23.2 does speak about testing procedures, although I don't have a copy in the office for any exact requirements.

 

[cvg]

if you're not inspecting (or having the owner or his designee) inspect reinforcing, you're not following the law (code).

and there is the rub, the owner always decides if they are going to pay for testing to be done, regardless if it is specified or not. An EOR cannot just show up on a job site and start inspecting if he is not under contract. In fact insurance may not pay any claim for work done while not under contract. So it is up to the owner to make sure testing gets done and many owners are willing to take the risk. Unfortunately, this happens with public agencies just as much as it does with private development. Otherwise, I agree that a good QA plan is cheap insurance for the owner and will generally result in higher quality work being done.

 

[JohnnnyBoy]

I agree with CVG which is one of the major reasons I posted this, because when we dictate we need testing done, and a total of most likely minimum 5 inspections for a structure it will add a lot of cost to the client...which they sometimes refuse. Now for larger projects we will not give compliance for the building without doing rebar inspections and have certain structural concrete tested, although there is still a lot of the construction that is left unsure and assumed to be checked by the superintendent of the site.

For smaller jobs (Residential, Small shops) Owner typically never pays for testing or inspections. In this case the risk of failure is equally as high, catastrophic failure much lower but the risk on the engineer is still there with no real power from us other than losing the client to another engineer wiling to design and leave the client do with as he will.

 

[Nor Cal SE]

Lots of good input on this thread.

To further CVG's post, it is true that once the stamped/signed project documents get transferred to the hands of the client, and eventually the general contractor, then the EOR often will not have all the power to actually implement the testing, though the testing should've all been specified according to IBC Chapter 17, and any additional requirements deemed prudent based on project specifics.

However, the EOR is also frequently contracted to provide construction support, including period site visits. As a general practice, I recommend very early in the construction process getting a feel for how "on top of things" are the site personnel hired by client, the parties who are independent of the contractor (often an inspector and/or construction manager, at minimum). You can get a feel for this based on your first visit to the construction site, and whether you find any discrepancies from your construction documents that the CM or inspector did not previously present to you. Some inspectors and CM's are great and will find every miniscule discrepancy. Some are slightly less observant, and for this situations, I recommend not only extra attention to detail on your site visits but occasional reminders to the CM and inspector of what tests are required and when.

Anything that can help prevent substandard construction is a victory for everyone involved.

 

[dik]

CSA A23.1 pretty much sums it up:

4.4.1.2 Owner’s responsibilities
It is the owner’s responsibility to ensure that the requirements of this Standard are met. The owner may delegate through contractual arrangements the necessary roles and responsibilities. Unlimited access to the work for purposes of inspection and selection of samples shall be available to the owner at all times.

4.4.6.3.1
Not less than one strength test shall be made for each 100 m3 (or part thereof) of concrete placed. A minimum of one strength test result is required per day for concrete of a single mix design. When high-performance or high-strength concrete is involved, or where structural requirements are critical, the owner may require a higher frequency of testing, which shall be defined in the contract documents.

Dik

 

[JedClampett]

In our area, part of the building permit process is for a Certificate of Special Inspection to be filled out. The owner assigns someone to do this, hopefully us, and I sign and seal it for my designs. At the end of the project, I get the form back and sign the bottom verifying that the special inspections have been done.
I suppose that there's some way to skate on this. But it seems to be a pretty good system. An Engineer needs to take responsibility for the Special Inspection being done. At the end it's certified.