That's a lot of steel! 2

[BCPeng]

There's a project ongoing that requires some very tight reinforcing steel placement.
How would you specify concrete for this job? Is this too tight for even Agilia to flow through?

Why could they not have used larger steel with more reasonable spacing?

 

[JoelTXCive]

That looks too tight to me. Effectively, you have 1 gigantic 'bundled bar' structure. The concrete might just form a shell around all the rebar.

The photo caption mentions 'treatment plant', so maybe it is an ACI 350 structure. With ACI 350 you can get some pretty steel intensive designs.

 

[Rabbit12]

I can't believe that joint would meet any ACI minimum spacing requirements.

 

[SlideRuleEra]

If this is the project, the firm with the design-construct contract appears to be incapable of performing design work needed. Rebar "spacing" in the photo is unacceptable, there is no concrete mix for that situation. Adequate spacing between rebar is needed for the concrete between bars to be structurally sound... there is physically not enough room between these bars for that to happen.

One "reason" an unqualified engineer may have used "small" rebar was to allow lap rebar splices... which, in most applications, are limited to #11 bars, and smaller. The photo shows what could be the result of that type misguided, single-minded attempt... likely made to "save money" on splices.

http://www.SlideRuleEra.net

 

[MIStructE_IRE]

That’s not going to end well. Without even getting an aggregate between the bars, the concrete outside the bar is just a shell and won’t properly contribute to the overall cross section.

 

[dik]

Terrible reinforcing... won't work...

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

-Dik

 

[BAretired]

Unbelievable!

BA

 

[dik]

The picture was photoshopped?

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

-Dik

 

[Tomfh]

Hopefully they have some special mix and placement methods to avoid the obvious issues with such congestion!

 

[dik]

...place the concrete with a teaspoon.

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

-Dik

 

[JoelTXCive]

 

[hokie66]

I have seen some congested areas, but that is the worst.

 

[Lomarandil]

Ah yes, the penny wise engineer's favorite.. replacing a reinforced concrete structure with an equivalent "rendered steel" design.

----
just call me Lo.

 

[dik]

The rebar has to be weldable, and you can forget the concrete... just have to add fire protection.

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

-Dik

 

[NorthCivil]

I dont work on jobs like this, but would jobs of this critical of a nature not get an engineering peer review?

 

[dik]

In 50 years, I've only had one project that was peer reviewed, and that was the floodway hydraulic ram connections. A mock up was also load tested. I've only had one project that was reviewed for constructibility and the only comment was that I used HSS 5x5 posts for supporting HSS 6x6 cross members for a cable tray component... They came to understand that it was easier to do a fillet weld all around and likely more water resistant. A lot of stuff I've done is critical, but not reviewed.

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

-Dik

 

[dik]

Scary part for Halloween... maybe it was!

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

-Dik

 

[structuralCADspecialist]

I guess they figure they're just going to use high-flow concrete. The pressures will be immense.

It looks strange to have 'clusters' of smaller vertical zone bars close together like that and makes me think "why not just less larger diameter bars". I'm sure there's a reason but I also know that many engineers spec whatever their computer program (or broken spreadsheet) outputs.

Given the user name BCPeng and the project name "North Shore Treatment Plant" I believe this project is the treatment plant in North Vancouver, British Columbia Canada. There is a massive contract dispute currently happening and the main contractor has apparently walked off the job. There are rumors that the construction drawings are absolutely horrendous and constantly being revised. A peer review is desperately needed.

In my line of work I see lots of reinforced concrete drawings. In my area (where I believe this project to be) they are particularly bad. Basic design concepts are overlooked perhaps the most common one being rebar congestion. Design work itself is extremely poor and frequently does not meet code. Sometimes there is too much rebar (in places where it's doing absolutely no good) and other times it's completely missing. Three residential buildings I know of either required extensive rework and/or are not to code. Not only are the designs bad the placing crews are often unskilled.

It's easy to say "it's like that everywhere" but I've seen drawings from other jurisdictions (mostly the states) and they are way better, or at least to code. There's something weird going on with how they teach concrete design in British Columbia.

 

[SlideRuleEra]

...would jobs of this critical of a nature not get an engineering peer review?

No. Scheduling is too tight, "time is money". Too many other aspects of this type/size project, like mechanical, electrical, permitting, etc., to be coordinated.

http://www.SlideRuleEra.net

 

[JoelTXCive]

This looks like a large project. On our large projects; we usually have a project representative checking on the project regularly; and the city/municipality might have an inspector too?

I cannot imagine someone wouldn't say "Hey Mr/Mrs. Engineer...the spacing looks a little tight here" I would hope they would say that before there was $200k of steel in the air.