CR4 - The Engineer's Place for News and Discussion ®


Previous in Forum: Water Treatment Calculator for pH Reduction   Next in Forum: Unusual Method of Prestressing Concrete
Close
Close
Close
15 comments
Power-User

Join Date: Nov 2015
Posts: 335

Stress Analysis

02/10/2016 3:39 AM

I just thought, the engineers who designed and implemented this, have learned stress analysis the wrong way.

My sympathy to the people of Taiwan.

__________________
"And ye shall seek me, and find me, when ye shall search for me with all your heart."
Register to Reply
Pathfinder Tags: Stressed slab
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Guru
Technical Fields - Project Managers & Project Engineers - New Member

Join Date: Oct 2013
Location: Texas.Baytown
Posts: 697
Good Answers: 26
#1

Re: Stress Analysis

02/10/2016 7:29 AM

It happens in the USA too. I know i have seen it.

__________________
If you want to know how well a broom works you do not ask the guy selling the broom or the guy who designed the broom, you ask the guy using the broom.
Register to Reply
Guru

Join Date: Apr 2008
Location: Chicago
Posts: 1949
Good Answers: 60
#2

Re: Stress Analysis

02/10/2016 8:14 AM

You've seen oil cans used in load bearing columns? In the US?

__________________
If you put a light on something? What do you do next?
Register to Reply Score 1 for Good Answer
Guru
Technical Fields - Project Managers & Project Engineers - New Member

Join Date: Oct 2013
Location: Texas.Baytown
Posts: 697
Good Answers: 26
#3
In reply to #2

Re: Stress Analysis

02/10/2016 9:08 AM

No, i have seen weld rod laid down in a prep and just welded over(flux and all). All i am stating is the US has contractors that are willing to cut corners just to save a buck. It was my job to assure that the structure met code.

__________________
If you want to know how well a broom works you do not ask the guy selling the broom or the guy who designed the broom, you ask the guy using the broom.
Register to Reply
Guru

Join Date: Apr 2008
Location: Chicago
Posts: 1949
Good Answers: 60
#5
In reply to #3

Re: Stress Analysis

02/10/2016 2:49 PM

For the sake of argument. I could easily weld over a flux crusted prep weld and create a structurally sufficient weld. If it looks like there would be a issue, I could identify it and clean the flux and re weld as necessary. It might not be as pretty to skip around, but it would suffice and is a far cry from creating huge unstable pockets in the load bearing columns.

..that said.. I've worked for contractors willing to do anything to save a buck, and it's frustrating as hell!

__________________
If you put a light on something? What do you do next?
Register to Reply
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 19700
Good Answers: 737
#6
In reply to #5

Re: Stress Analysis

02/10/2016 5:11 PM

I think texasron is talking about loose rods laid in the root area of a weld, and then just capped over, so that the resulting "weld" penetrated maybe even less than half the metal thickness. I've heard stories of Liberty ships done that way.

__________________
In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
Guru
Technical Fields - Project Managers & Project Engineers - New Member

Join Date: Oct 2013
Location: Texas.Baytown
Posts: 697
Good Answers: 26
#10
In reply to #6

Re: Stress Analysis

02/11/2016 8:31 AM

Yes! The Ultrasonic inspector came to me and was confused as he had never seen that condition. He stated it was like there was no weld there, no fusion no nothing. I had an outside contractor come in and air arc the cap and we saw just rods in the weld. This was on a stadium support leg. Contractor was fired and all welding done by that contractor was inspected.

This is not the first time. One job they called me in on there was I beams from outside the US that had just been butted up and a skin weld, then grind, paint for visual, was done. They had picked up the beam and it hit the structure while lifting into position and it just split into two parts and hit the ground.

Bottom line i have developed a mistrust of any supplier be it US or foreign.

__________________
If you want to know how well a broom works you do not ask the guy selling the broom or the guy who designed the broom, you ask the guy using the broom.
Register to Reply
Guru
Hobbies - DIY Welding - Wannabeabettawelda

Join Date: May 2007
Location: Annapolis, Maryland
Posts: 4002
Good Answers: 218
#4

Re: Stress Analysis

02/10/2016 1:08 PM

I doubt the oil cans were on the original drawing. The fault may lie with the construction manager on-site to save some money on concrete but we'll have to wait for a full investigation to really be able to comment. Inspectors may have been bribed or they just didn't see the 'construction'. Lessons about ethics always seem to have to be learned the hard way. It's too bad the ones responsible weren't living in those flats. I'm glad I work for a company where anyone, and I mean ANYONE can call a stop if they see something they don't think is right. And the management will back them to the hilt.

Register to Reply
Guru

Join Date: Oct 2008
Posts: 39041
Good Answers: 1533
#7
In reply to #4

Re: Stress Analysis

02/10/2016 5:38 PM

First, I completely agree that engineers very likely would never design time bombs into their work.

I can see unethical builders doing this to save a buck.

I salute your company for empowering their employees to have a voice in making things better for everyone.

Register to Reply
Guru
Canada - Member - New Member

Join Date: Jul 2013
Location: Canada but south of 49
Posts: 713
Good Answers: 17
#15
In reply to #4

Re: Stress Analysis

02/16/2016 11:42 AM

Good policy where anyone can call a stop. It's only common sense to have it. Engineers "usually" design for appropriate conditions-I cannot comment on all of us, but unless they are involved in the actual construction, it's anyone's guess as to how structures are actually built. Not uncommon to try to cut corners to save on cost and "developing" countries are especially prone to short cuts and other skullduggery.

This is clearly not an engineering change due to field conditions. Those are somewhat common, but procedures should be in place for any such possibility.

__________________
Never stop learning
Register to Reply
Guru

Join Date: Mar 2012
Location: Out of your mind! Not in sight!
Posts: 3944
Good Answers: 89
#8

Re: Stress Analysis

02/10/2016 8:24 PM
  1. Why mentioning engineers if seemingly building practice is at fault? For me a builder is not same as an engineer
  2. They arrested the developers - no say that it was an engineering fault
  3. Even if you know how to do things right people might not do the right thing. So your assumption they learned stress analyses the wrong way is wrong.
  4. The golden rule for the Golden Dragon building was that blue cans can save them buckets of concrete

My sympathy to the people of Taiwan too.

__________________
Common Sense Dictates
Register to Reply
Power-User

Join Date: Nov 2015
Posts: 335
#9
In reply to #8

Re: Stress Analysis

02/11/2016 2:55 AM

I mean, QA/QC engineers and consultant. Taiwan is an earthquake prone country, I bet design consideration should be around 7.5 at least. It's just a magnitude 6+ tremor, the design should stand through.

__________________
"And ye shall seek me, and find me, when ye shall search for me with all your heart."
Register to Reply
Guru

Join Date: Mar 2012
Location: Out of your mind! Not in sight!
Posts: 3944
Good Answers: 89
#13
In reply to #9

Re: Stress Analysis

02/11/2016 8:12 PM

Just as a note, this will all change when a magnitude 8 one comes around. Just saying!

__________________
Common Sense Dictates
Register to Reply
Guru

Join Date: Jul 2012
Location: Madison, WI.
Posts: 926
Good Answers: 39
#11

Re: Stress Analysis

02/11/2016 9:29 AM

Strange. It looks as though they actually space the cans fairly evenly. Seems to have been a very deliberate effort. Perhaps a misguided attempt to duplicate roman concrete practices? In any case, it seems to me to be a fairly obvious culpable negligence case at the very least.

__________________
Knowing is the end result of learning, not believing.
Register to Reply
Power-User

Join Date: Sep 2015
Posts: 176
Good Answers: 11
#12

Re: Stress Analysis

02/11/2016 11:09 AM

Very obviously, this is a contractor construction shortcut, nothing to do with stress analysis/engineering. From my experience, this was a case where the contractor attempted to stay on time/on budget, by creating a symmetrical void in the column. Kept pouring concrete even though was running out, or saved time by preventing the pouring of concrete.

Or......some organized crime syndicate decided not to bury some poor stiff in the column at the last minute.....

__________________
Invention is the mother of necessity.......there are always opportunities for improvement!!
Register to Reply
Guru
United Kingdom - Member - New Member

Join Date: Aug 2010
Location: Resting under the Major Oak
Posts: 4235
Good Answers: 172
#14

Re: Stress Analysis

02/12/2016 5:19 AM

A major dam project in the UK had to be started afresh because under the original contractor half the cement was going out the back door.

It's the same the world over unfortunately.

__________________
Pessimists are rarely disappointed.
Register to Reply
Register to Reply 15 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

Brave Sir Robin (1); IdeaSmith (2); JE in Chicago (2); Kevin LaPaire (1); lyn (1); Mr. small (1); rashavarek (1); texasron (3); TonyS (1); Tornado (1); wolfie62 (1)

Previous in Forum: Water Treatment Calculator for pH Reduction   Next in Forum: Unusual Method of Prestressing Concrete

Advertisement