Dismantling an industrial roof after a blast

[Groot]

Greetings,

Would anyone have a clue on how to dismantle this without taking too much risk or damaging the machines beneath it?

Cheers

 

[MIStructE_IRE]

Can you erect a temporary crash deck close to the underside of the existing roof?

 

[Agent666]

Talk to some demolition contractors, they'll come up with a plan.

If the risk is there regarding damage to the plant or risk of disrupting ongoing production (whatever that might be) or even temporary weather protection, then some temporary overhead protection could be installed, a crash platform/barrier to protect against smaller bits and pieces falling may be warranted for example.

But I'd imagine simply craning out complete sections of the damaged structure would be the way they'd do it rather than removal of cladding and individual members one by one if there was risk of things falling and damage occuring.

 

[Groot]

You can't put workers below the roof as is, the fibrocement tiles can fall anywhere anytime, workers would be at serious risk

also the roofing has collapsed so much that touching the machine

maybe with some clever sequence, so that worker stay protected, but wouldn't making a protective structure that big be quite expensive ?

overview of the site, arrows designate the 2 parts that have been affected.

it's in beirut lebanon, near the port, after the mega blast few days ago

The arrow on the right corresponds is another damaged part, same issues, more complicated truss though

 

[Groot]

Agent666 - "craning out complete sections of the damaged structure" - yes, that was what i had in mind. I wonder about how big the crane needs to be though. Access is from the road between the two structures (the small hangar and the main bldg), can't do it in another way.

If someone knows a clever trick to make those tiles (fibrocement, corrugated sheets) fall without going into super expensive setups, that would simplify the issue by a lot

 

[r13]

Agent666 - "craning out complete sections of the damaged structure" - yes, that was what i had in mind. I wonder about how big the crane needs to be though.

Same idea here, but may require torch the roof to several manageable portions. Read the structural prints to determine safe location for cut. Then use crane and man-basket to cut from top. You might need two cranes operate together to provide stable platform for work.

 

[phamENG]

Sounds like you need to some creative demolition with nearly zero resources (since the applicable resources are probably stretched too thin to have any reasonable expectation of getting them this year).

How about safety netting? You wouldn't need much of it - enough to cover an area of work. Either come up with an anchorage system to the walls or some sort of temporary frame. You could build a portable tower out of some sort of scaffolding material (or scrap you find on the ground) with large casters that can moved around and protect the worker while anchors are installed. Stretch the netting, and drop small sections of roofing into it. It's not going to guarantee that nothing hits any machines, but it should significantly reduce the damage.

I'd be hesitant to crane it out. One, you'll probably be on a waiting list. Two, how do you define "in tact" sections? I don't see any in the pictures. A small crane to remove the trusses when the time comes, and maybe with a basket to lower a worker down to remove the roofing if you can get one, but from the pictures I don't know about removing large sections.

 

[Groot]

phamENG - not sure about the netting, horizontal loads could be quite big if a truss falls (they're seriously damaged, with strut buckling and LTB). The fixing of the net would mainly be done on masonry, would need extra structural element to route the loads to structural members. There's a lot of damage from the blast, even on concrete structural elements. What i'm looking for is to take the machines out before repairing (maybe partially demolishing) the construction.

Maybe MIStructE_IRE proposal of a crash deck / working platform just under the roof is simpler after all.


retired13 - can't put 2 cranes, i only have crane access from one side, and there's a significant distance to the truss members, huge crane i guess, $$$

 

[3DDave]

This seems like a great application for the use of drones to place rope and hooks. There are some with sufficient carrying capacity to manage this task.

Alternatively there are remote controls available for some construction equipment so the risk to workers is minimized, depending on the access to floor space to maneuver. An adapter to extend the reach of a loader/excavator to poke the roofing loose would be pretty simple.

Example remote system:

https://www.youtube.com/watch?v=8repce2dYe8

(no affiliation.)

 

[Ron]

Older fibrocement panels typically are loaded with asbestos. Check before you demolish.

 

[Groot]

Ron - they definitively are, one problem at a time. spraying PVA glue should help fixing a lot of it. Maybe there's better ways?

 

[MIStructE_IRE]

Out of curiosity, how far away from the blast source is this building?

 

[r13]

Progressive demonstration from free access toward machine, then pull machine out, and demo the rest.

 

[Groot]

MIStructE_IRE - almost a mile away.
Pic from hangars nearby ground zero:

 

[Groot]

retired13 - could be, i'd need to find a crane that can lift 20 tons tough, maybe 10 tons if i manage to dismantle the machine enough. Pretty big one i guess, that calculator suggests a 200 tons crane ...

https://nckynningsrud.com/en/cranecalculator/

 

[Groot]

Ok, i guess it's going to be a crash deck near the roof, by using scaffolding. Got to figure out a way of assembling this without putting people at risk.

 

[r13]

For building, you can do a segment at a time. For the machine, I don't know its weight, but you shall be able to find a way to put something (log maybe?) underneath in the front portion, and sort of toll-roll it out inch by inch. Again, entirely, or a segment at a time, depending on the equipment available. The old Egyptian can move that massive stone....I think you can too Good luck, and be safe.

 

[Groot]

retired13 - yes they managed to get it in with a crane, bur from inside the building, hence with much smaller spans. I guess the same route is the way to go to take it out. Otherwise, inspiration from the egyptians will be quite usefull Many thanks to all, i'm gladly surprised to see that this forum is still alive so many years later.