field review - what should I check? 14

[newlearner]

I am a structural engineer. I would like to know what should be done for field review as a professional in the concrete construction site. Any special item I should check? Comment and suggestion are appreciated very much. Thank.

 

[bridgebuster]

When in doubt always consult NYSDOT. Attached is the unoffical construction inspection manual. Concrete construction starts in Section 500; about halfway through the file.

 

[JedClampett]

Check the diamater (by the way not that easy) and spacing of reinforcing. Besides that, walk around with with a clipboatd and a pissed off look on your face and pretend to write something down every few minutes.

 

[dik]

I often use a voice recorder... I have trouble finding a flat surface for using the clipboard.

Dik

 

[TDAA]

Follow Jeds advice closely.

Add a squint / eyebrow furl with a head cock to the side. Hold for 5 seconds, add a few degrees, hold and release.

Watch as people look at what you just looked at.

Points of interest:
1. Required steel is there and in place
2. Spacing
3. Clearance
4. Splices
5. Size
6. Orientation
7. Construction joint locations (if specified on plans)
8. Isolation materials at walls / pipes if needed
9. Water stops if needed
10. Embedded steel for the next pour is in place
11. . . .

 

[JAE]

This thread here: thread507-275876 doesn't specifically address concrete but it might be appropriate for you to read.

 

[dhengr]

Actually, you can save yourself a lot of time if you inspect only the items which have been done incorrectly and then ignore the rest of their work, and get back to the office, and the real money making work.

In effect, this was what my first boss was saying as he bitched about me burning his profits on the job, when I took too long checking shop drawings or out on inspections. You only ended up with 7 redlined items on those shop drawing, or you only came back with 4 items which needed fixing on this inspection trip, why didn’t you check those things first and be done with it, what took you so long? Obviously with his vast experience over mine, he was much quicker at seeing what needed red lining, or seeing clear across the construction site what needed inspecting, but that comes with time. So, take the time and use and study aids like those suggested above. Furthermore, you were involved in the design so you should know some of the spots that might need a little special attention.

So, give er hell, be thorough, and keep in mind that forming carpenters, iron workers and cement finishers don’t know everything, or even nearly as much as they think they do. But, you can still learn by watching them and taking an interest in what they are doing. Why does it go together easier this way, can my design account for that in the future?

 

[Bobber1]

I always make a checklist of the things that are important. I do this because jobsites are noisy and distracting, the superintendents are trying to intimidate you, etc. The checklist keeps me from getting distracted and makes sure I just check the important stuff.

If the contractor is nice to me, I will give him a copy of the checklist in advance (with a lot of things added), and usually, viola - everything is fixed by the time I get there.

 

[newlearner]

Thank you very much for all comment, for the check list and for templete of Site visit report. If I have a chance to do field review, I will take your advice.

Thank JAE for providing link to "Construction Admin - Legal Responsibility". I do have some questions concerning responsibility. I will read comments there.

Your comments are appreciated very much.

 

[rscassar]

Your company would have issued a specification with the design drawings. Everything that is requested in the specifications should be requested on-site. Obvious that you look at reinforcement, size, spacing, splices, cover etc. Look for any reinforcement which has been displaced for conduits, if any reinforcement has been cut to make way for a pipe, make sure extra reinforcement has been laid next to the opening.

Request concrete tests, I would ask to see 1 test result per 50 cubic metres of placed concrete.

 

[hokie66]

In addition to all the above, make sure the reinforcement mats are adequately supported. Concreters are big footed oafs who will can make short work of lowering bars if they are not firmly supported. Another stupid thing to look for is columns which are cast too high.

 

[rscassar]

hokie

What are the ramifications if the columns are cast too high? I image it would affect punching shear because of the change of location of the construction joint and the flexural capacity of the slab over the support.

What are the rectifications if the columns are cast to high? Would it be as simple as jackhammering the columns down to the correct level.

Have you noticed columns poured to the incorrect level regularly in your time and how do you ensure the builder cast's the columns to the correct level?

Apologies for hijacking this thread, it is something for my own interest when performing field inspections.

 

[hokie66]

Yes, that is correct, punching shear capacity is compromised because of the slick, formed projection into the slab. Also, you can't get any bottom bars to go over the column. And yes, I have had this happen a few times, thus my cautionary advice. If it is caught early enough, a sawcut should be used to make the joint neat, then chip off the excess. Unfortunately, sometimes it is only caught when the formwork, and maybe the reinforcement, is in place. Chipping it off at that stage makes a messy joint, with likely cracking off the corners below the slab, which then require repair.

Ensuring builders do the right thing? I think that is impossible. Ignorance can't be eradicated. We just have to do the best we can. I think some builders deliberately cast columns high to aid in making neat joints.

 

[pwht1]

I'm doing inspections on a job at the moment in which they regularly pour the columns 50-120mm above the forms ( 2 or 3 columns in every pour). It's become very annoying, especially when the builder doesn't do anything about it until I point it out the day before the pour.

Newlearner, you also need to make sure that the builders pour the columns before they pour the deck. I prefer at least a day prior.

 

[hokie66]

Tried to pull that one on you as well, pwht1? Sounds like you are seeing a lot of the dumb stuff they do on site. Unfortunately, a lot of young engineers get very limited opportunities to see how their designs are implemented.

 

[msquared48]

Check to see that the contractor is working off the current set of approved plans, and the latest answers to any RFI's.

I often have had nightmares about this...

Oh, and DO NOT approve anything that is either not in place yet, as in "I was going to do that tomorrow", or that you cannot see, as in " I was going to call you, but just had to pour".

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[pwht1]

Oh yeah Hokie, lots and lots. Today, they dumped all the slurry they use to prime the concrete lines on the deck so it gets mixed in with the concrete. I don't know what that'll do but it's poor workmanship.

Also NewLearner, tell the builder that you are to approve all cutting and bending of reo. Otherwise before you know it all of your column starter bars will be cut off because they clash with a PT anchor.

 

[BAretired]

Pouring columns higher than the underside of the next slab is unacceptable. It results in a peripheral shear problem. We must make the contractor chip out the top concrete in each column until it is flush with the forms for the slab. No other solution will suffice.

BA

 

[hokie66]

Agree completely, BA. I hope my comments weren't interpreted otherwise.

 

[Zambo]

Whoops, BAretired and hokie66 I always expect the columns to be cast 20mm higher than the slab forms. The reason, as mentioned earlier is to make a neat joint. Of course if higher (say 50-120mm) of course the excess concrete would have to be chipped off as it would be impossible to correctly place the rebar.

But is 20mm higher unacceptable? I'm always ready to listen to advice.