When to require stamped drawings for temporary building shoring 1

[RFreund]

Let's say you have a renovation project which requires an existing beam to be supported while you remove a column, or something along these lines. If you put demolition drawings together or even if you don't - I would think that you would call out for the beam to be shored. You might even provide a reaction or design load. You may even require that the shoring design be delegated to the contractor and even require it to be stamped. I suppose you could go so far as to design the shoring. Or you could just show the final condition and chalk up the shoring of the beam as means and methods. I'm curious to know how far do you typically go? Is there a technically correct answer to this? If you delegate this design or leave it up to the contractor do they need to have an engineer design the temporary shoring?

EIT

http://www.HowToEngineer.com

 

[r13]

Reactions for temporary shoring will be affected by the method deployed by the contractor. I'll show the final condition with note that calls for construction support, and for more involved support/conditions, ask to submit plan for review. A stamped calculation is required for complicate supporting schemes, and for supporting extremely important objects.

 

[BAretired]

I believe it depends a lot on the circumstances. For regular, uncomplicated formwork such as fly-forms on a concrete building, it is not common practice to require engineering seals for the formwork.

For specialized structures such as bridges, water reservoirs, spaces where cranes are working overhead or in fact any unusual structures which present a potential hazard to the workmen or the public, it is a good idea to specify engineering input along with engineering seals.

BA

 

[RFreund]

Thanks for the responses. In general that makes sense. I was trying to see if there was some sort of consensus on what is "important" or "complex" for building type structures. I know it's a judgement thing, but thought maybe there could be some sort of guideline. For example the following conditions seem they would warrant a stamped set of plans:

[ul]
[li]If you need to support a portion of a structure that would be in use during construction.[/li]
[li]If the portion of structure is free to translate (no longer attached to a diaphragm or LFRS).[/li]
[li]If there is something preventing you from locating the shoring directly below or near the member that requires shoring (i.e. shoring on an upper floor which can't be supported by shoring below and must be 'transferred' on the same floor)[/li]
[/ul]

I'm sure there are more cases and there could even be exceptions to that list.

I'm wondering if OSHA or any other governing body has any recommendations on this. I know OSHA has them for excavation shoring, but I don't know that they have any for building shoring.

Going the other direction - can you make the argument that the shoring is all on the contractor as part of means/methods and your drawings only represent the final condition?

Thanks again!



EIT

http://www.HowToEngineer.com

 

[r13]

All three would require plan show supporting scheme and calculation, since to be supported are live activities with high uncertainties..

 

[BAretired]

@RFreund,

I had a particular reason for mentioning water reservoirs in my earlier post. Many years ago, while working for a multi disciplined engineering firm, I was involved with the design of a water reservoir. It was a circular shape with a concrete wall supporting a spherical dome roof. The design was carried out as usual, detailing and specifying work to be built but leaving falsework design to the contractor.

Work proceeded without incident until placing concrete on the roof was nearly complete. Concrete had been placed over most of the dome except for a small circular area in the middle. Suddenly, the formwork gave way; the roof began to descend and the increasing air pressure blew out the middle circle of plywood as the wet concrete continued to fall to the ground along with a crew of concrete placers. Most of the crew were lucky to escape injury, but two men died and one was seriously injured as they fell onto a tangled mass of reinforcing steel.

The expert witness at the coroner's inquest was a principal in a well known and highly respected firm of bridge engineers. He stated that his firm's practice was to ensure that shop drawings for falsework be sealed and signed by a professional engineer and submitted to his firm for review. This was a wake up call for me.

BA

 

[SlideRuleEra]

BA's example is spot on. As a former bridge contractor, I had to submit our falsework plans to the DOT for the cast-in-place concrete superstructure of a new highway bridge over an active railroad track.

Another bridge-related, contractor-designed temporary structure that gets close scrutiny are cofferdams. Unless designed and constructed properly, they can collapse in seconds, often with no survivors.

If there is something preventing you from locating the shoring directly below or near the member that requires shoring.

Very insightful observation. While restoring our (electric utility) corporate headquarters, we had a consulting engineer design permanent repairs and a competent contractor perform the work. However existing conditions were so complex (electrical conduit and piping embedded in elevated floors) that management had me do the temporary heavy structural shoring design in-house to relieve both the consultant and contractor of liability for that aspect of the project.

http://www.SlideRuleEra.net

 

[Guest090822]

BAretired hit the nail on the head. Anytime a life is at risk then get an engineer to design the falsework. I used to have to remind my junior engineers that 95% of all engineering disasters happen DURING construction.