Concern over steel erection procedure 1

[DerbyLoco]

The picture shows an 8m long beam left hanging on 4 bolts. I don't have site access but the section looks to be about 200 x 100 RHS and the bolts are about M20 through top and bottom flanges welded to the section. This looks very bad to me and likely to damage the structure - what does the group think? The beams and posts will eventually be joined to form a ring as part of a ropeway adventure feature and my interest is just as a byestander. All the beams have been placed in the same way and are often left overnight or longer.

 

[drawoh]

DerbyLoco,

This sounds like a question for forum507. Perhaps you should red flag this and post there.

--
JHG

 

[JStephen]

"This looks very bad to me and likely to damage the structure"..."All the beams have been placed in the same way and are often left overnight or longer"

If the only concern is damaging the structure they're erecting, but they're already doing it that way with satisfactory results, it seems like a moot point.
If it's a safety issue, that's a little different, but would generally be the concern of the erector and/or designer and/or the owner rather than curious passersby.
In the US, OSHA does have some regulations relating to steel erection.

 

[desertfox]

Hi DerbyLoco

To me it depends on how the planning for the steel erection goes, if the bolts are tightened and the bolts have been sized to take the offset mass of a beam as shown in the photo then I don't see a problem.
That said it does appear odd to just bolt a beam to one end and leave it hanging.

 

[DerbyLoco]

I don't agree that ignoring potentially dangerous or unsafe practice on the grounds that you are not personally involved is an excuse for not doing anything. Likewise the fact that it appears to work because it did not fall down does not mean that it must be OK. The road to hell is paved with good intentions! Yesterday I witnessed one off the erectors using a pallet on the forks of a telehandler to work at 10m so I fear they are cowboys. I will take that up with the HSE. Thanks anyway for your input.

 

[desertfox]

hi DerbyLoco

Unfortunately we were not party to cowboys using pallets off a telehandler all you gave was a photo of a structure in an area which appears to be secured against members of the public.
When a bridge is designed the engineer responsible for the design has to know at each construction stage the steel members in that part are safe from excessive stress even though the bridge is not complete.
All I see is a steel member bolted at one end like a cantilever beam, it doesn't appear to be hanging down excessively as it would if the bolts weren't tightened correctly or causing any deflection to the member its bolted too but I agree that its odd.
So you saw the structure in the flesh then tell us what you thinks going to happen to the structure left in this unfinished state temporarily I assume.
I've seen flag poles cantilevered horizontally off buildings similar to the structure again that wouldn't be safe if the bolting down wasn't done correctly.

Nobody said we should ignore unsafe practice because we are not involved but we should establish facts first and there is no harm in taking it up with the HSE, but don't jump to conclusions about what other people think because you didn't get the answer you wanted. In fact if you feel so strongly about it why didn't you contact the HSE straight away before posting here?

 

[DerbyLoco]

I have taken the matter up with the company who have supplied the structure. I agree in principle that the installation procedure might be OK but that assumes that the designers are aware of how it is actually erected and not how they have said they want in done. I know from my own experiance that the boys in the field will do what they think is best/easiest and not the way they were told to do it.
I looked at reporting the safety breach to the HSE but they don't make it easy and they seem to indicate concerns should be taken up with the people on site first. I am certainly not going to question a bunch of steel erectors about their working practices as I am sure I would learn some new words if I did but I feel duty bound to do something about it.
I thought the hanging beams were just odd really that's why I asked but the safety issue has sharpened my concern as if they will risk there own safety they are more likely to ignore a work statement from a designer.

 

[desertfox]

HinBerbyLoco

I agree that people in the field don't always follow the recommended procedure, I do both site and office work and so I see both sides of the coin.
Sometimes I agree with the field workers if there is good reason to change a plan.
In the case you presented I cannot see a logical reason why they left it hanging, it would have been easier to leave the beam on the deck until they got the other upright in place before bolting the beam on, it will be interesting to hear the response you get from the company responsible, please post it when you can.

 

[DerbyLoco]

I will if I get anything sensible! My thoughts were also that it would have been best to put up the posts first. I suspect that the ground conditions are to poor for them to easily move the cherrypickers they have on site as they are fequently grounded in the mud whilst the telehandler has bigger wheels and is more mobile.

 

[weldstan]

This appears to be a proprietary design/erection method that I have seen recently and the structure appears to be light weight. Four bolts should be more than adequate for safety before final tightening.

 

[LittleInch]

I think they will get away with it unless the wind picks up to the point where it starts to vibrate or wave backwards and forwards due to vortex shedding. Static load it looks fine, but movement or hanging something off the far end and it would be a different story.

Using the ground conditions as an excuse for not using the man lift is a poor excuse on their behalf. Again they will probably get away with it, but providing you find the foreman or even supervisor to discuss that with then he knows he isn't doing it right.

I would simply take photos, find the company online and then send them the photos and ask if that is their approved procedure. A copy to the council building works department will probably get more response.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[JStephen]

There are a lot of situations that are potentially hazardous if you don't know the details.
When I drive down the road and see a driver in the car next to me, that driver is "potentially" drunk, sleepy, doped, unqualified, etc. Because he's potentially unfit to drive, nothing happens. If I see something to make me think he actually IS drunk or otherwise impaired, that's when I get worried.

A friend posted a picture on Facebook yesterday of a couple of guys walking around on top of a watertower. That is potentially very dangerous. I don't think anyone felt obligated to call the fire department, though.

In the case of steel erection, typically, the steel designer designs the structure for the finished condition, and the erection company is responsible for working out how to erect it safely. Design of the structural members for stresses encountered during erection could be undertaken by either party. If you look at a partially erected structure, it is potentially hazardous, but whether it actually is hazardous would depend on how the design details and procedures were worked out. You certainly can design a steel beam to be cantilevered out by X number of bolts. Was that design properly done in this case? Is the erection crew following the proper erection plan? I haven't a clue in either case. But unless there is something that suggests that design is deficient or that the crew is not following proper procedures, I'll approach it just like seeing the guys on the watertower, and assume they know what they are doing.

If I'm the owner or owner's consultant or site safety manager or OSHA person or something like that, I may look into their design and procedures to confirm that they are in fact doing it like they're supposed to. If I'm a bystander, don't have any idea what the proper proeceures are or what design aspects were addressed, and don't see anything that is clearly a hazard, I'll leave it to them.

 

[3DDave]

Look at the

http://www.eng-tips.com/threadminder.cfm?pid=507

for some examples of poor planning. There's the building in Texas that recently collapsed, killing one of the workers. Same work site saw a worker killed by a truck a week later. There was also a bridge in Canada where the main beams went sideways. Both cases were due to insufficient bracing during construction.

From commenters on the other thread, it seems that structural engineers are not typically involved in verifying intermediate construction configurations and that construction crews may make their own alterations to plan without warning or permission. As has been mentioned by Henry Petroski, there is a cycle in which people get more comfortable pushing their accomplishments without realizing the margins are decreasing, until one day those margins are negative. If they are lucky, the structure fails. If not, the structure both fails and kills people.

I think the honest crews will either have the calculations there and the plan they are following, or they will be thankful you mentioned this oversight. The dishonest ones will get angry and claim they are insulted as a way to cover their incompetence. Remember that every construction collapse is at the hands of someone who 'knows what they are doing.'

 

[DerbyLoco]

Thanks for the replies. I posted the issue originally out of general interest as I thought the erection method somewhat odd and just wondered what the views of others were. The safety issue arose after my first post which made me think that maybe if they can compromise their own safety they would cut corners in other directions.

I have contacted the company about the H&S breach with zero response and they are still using the pallet on the telehandler forks. In my opinion safety is of universal concern and although I take the points made about being aware of all the facts I am comfortable with reporting the matter to the HSE.