I recently joined a new school district and my band hall is a giant box. It is constructed of large concrete slabs (about 25 wide and 30ish feet high and 12 inches thick) that were constructed off-site and brought to the construction. The short walls are three slabs long and the long walls are four slabs long. They are joined by some sort of rubber material similar to the caulk found in your bathtub. There may be some sort of structural member joining the slabs, but I can’t tell since the caulk joint is in the way. The roof is concealed by a drop-ceiling, but there are no supporting columns inside the building. None of the few interior walls appear to bear any structural load whatsoever. The building is completely detached from any other structure. The ground does have a bit of a slope, so the foundation at one corner of the building is a good three feet above grade. There’s a lot of concrete here.
In my uneducated opinion, it appears to me that if any one part of the building were to fail, the entire building would fail. The only secure anchoring places for the slabs are at the base and at the roof. If a tornado, for example, were to rip off a portion of the roof, there would be nothing left to help the wall withstand what would surely be a substantial wind load. I would prefer that my students and I not be crushed under a falling concrete wall.
Given that the building has stood for approximately thirty years, I have no reason to think that it will have a problem in the future. But, these wall panels are truly massive. Does this sort of building have a history of faring better or worse than traditionally constructed buildings in a storm or other catastrophe?
(I acknowledge that you are not architects or engineers who have examined the structure in question.)
The roof itself might tear off, it is probably a lightweight corrugated panel with insulation and roofing material, but those joists aren’t going anywhere.
Sounds like a panel building. More than likely, as this is a municipal building, it will be built to code. Unless a specific area calls for it, there usually isn’t a requirement for earthquake and high-speed wind/tornado certifications. I believe those come into play for insurance reasons if in fact you are within an area subject to those.
They are joined in some way, either by an epoxy, or fasteners, and possibly by both. So, no concern that these four walls are simply balanced on the concrete bad just waiting to be toppled.
Plus, as the other poster mentioned, there will be joists on top, more than likely steel beams or a truss like system holding the walls together. It would take significant wind-force to topple the building and I don’t think you’d survive either way at that point.
This isn’t so uneducated. Your exact concerns came up after the 2011 tornado in Joplin Missouri in which people were crushed by the walls of a tilt-up Home Depot. A study (pdf) by the Tilt-Up Concrete Association (which has a vested interest in clearing their name but there doesn’t seem to be any suspicion that the study is faulty) showed that the walls held up just fine to 200mph winds until the roof failed, then it all came crashing down.
It really can be a system as you describe, where if either a wall or the roof fails, the whole building may come down. The TCA recommended several methods of strengthening the roofs as well as recommending that tilt-up buildings rely on shelters rather than relying on the idea of tornado proofing the building.
That said, welding methods and the thickness of the steel used in the roof can play a large role in the strength so it’s impossible to say how strong a particular tilt-up building is. Joplin was also an F-5 tornado, which are really rare, so it’s extremely unlikely one will hit your school. And it’s hard to say what construction method would be better suited unless a building was specifically built with an F-5 in mind. The Home Depot seems to have held up pretty well until succumbing to what would probably destroy any other building too.
Tilt-up buildings compare very favourably to other construction types from natural hazards. For an earthquake, the rigid reinforced walls and relatively flexible roof handle the unique imposed motion well.
For a wind event, the entire structure is shear capable so can handle imposed wind loads very well. Loss of the building envelope (i.e. loss of the roof skin) would only increase wall pressure and wind uplift loads slightly. Assuming the primary roof structure is trusses or such, not an integral roof skin/structure, this just means internal property damage, not total structural failure.
the real danger with these buildings come during construction, as tilting the panels from horizontal to vertical requires unique rigging and a lot of skill. Then the walls must be temporarily braced whilst the structure is finished. lots of deaths locally from tilt-up construction failures.