Erecting Steel Framing over an occupied/existing building

[JAE]

US project - single story steel framed (beam, bar joist, and metal deck) roof.
A new addition is proposed over the top of the building either by new installed columns within the existing space or by clear spanning over the top with deep trusses.

Do any of you know of restrictions on erecting steel over a building that is occupied during the day?
The possibility exists that the erection could occur at night when no one is in the building but that still leaves partially erected and temporarily braced steel overhead with people below.

Are there OSHA or insurance limitations on this kind of construction?

It seems like steel members could be accidentally dropped on the structure causing failure and damage/injury below.
And even if occupancy was limited to the direct area below the addition, the damage to the existing roof might possibly have a domino failure effect and injure occupants one or two bays over.

 

[MiketheEngineer]

Yep - you have a problem - but it is done all the time. I would rather there were NO people in the building!!

 

[dhengr]

JAE:
I would assume that OSHA enters the picture someplace, they care about work site safety, the worker’s and the general public’s safety around the immediate work site. Why don’t you call them and get their directions on the matter. Maybe call AISC, a GC you’ve worked with or your friendly local steel erector for their take on the matter. Google, OSHA 1926, their Construction Stds.

That could be a real hassle, but you see it done in various forms on many construction sites. OSHA will at least say keep people out from under loads on a crane hook. And then, after some level of securement work can commence around and under the area even though final connections are not complete.

 

[JAE]

dhengr - I've done all that. No response from OSHA emails/calls. Nothing found on OSHA's website. Got feedback from various contractors and erectors.

Just wondering what the common/combined wisdom here at ET might bring.

 

[rowingengineer]

We have done a few heavy works over building in australia not the us, and we also do a lot of absailing work. Genrally we create a fall arrest work method statement. This arrest system can vary from application, but genrally we errect the main system at night genrally heavy nets over the existing roof using this as the structure and then install everything with a double tether. Our Genral rule is anything above 1000kg lifts will require two cranes one as the lifter the other as the tether.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[msquared48]

Hewck with the building below. What about the Taqueria truck for the workers. It would be absolutely devastating to hit that!

Parked cars, Pedestrians, Adjacent buldings, demolition damage. Seems like it would all fall into special liaqbility insurance with defined riders.

Are there any similar projects in your area where you could ask a few questions of those who have gone through this?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[Ron]

JAE....HIGH LIABILITY!!
Unless the existing structure could handle a dynamic event (beam dropped during erection) I would do nights and weekends and keep all out of building. Did an expert witness case a few years ago where a 4x4 was dropped from adjacent construction and went through a roof and damaged the structure, but landed in an unoccupied area....no one was hurt but could have been. Remember...it's construction...if a problem can exist it will exist!

 

[JAE]

Well, even with work at night I have my doubts - I remember a bridge girder in Colorado a few years ago - the erection of the girder was completed (perhaps at night) and during the day the traffic went under the girder.

A short gust of wind and the girder rotated laterally and dropped onto an SUV killing the family inside. So even after erection is "complete" there are still temporary guy cables and bracing that can be difficult to verify.

Still waiting for OSHA's response but was hoping someone on here might have OSHA rule references, etc.

 

[Ron]

JAE....OSHA simply says that if occupied space below, you have to have protection from falling objects....big object>>>big protection!

 

[JAE]

Ron do you know where that is written? What section in OSHA's rules?

 

[dik]

When I did the PP addition about 25 years ago, the work was done at night over unoccupied space... this was a major renovation with the addition of a whole new floor. The work was done progressively to prevent disruption to the ongoing businesses/shops.

Dik