Warren Theater: Why not build homes and schools to same standard?

[bchris02]

The Warren Theater miraculously took very little structural damage considering it took a direct hit. The primary reason for this is the standard to which the theater was built - it was designed to be able to take a hit. Question is, why not require at least schools to be built to that same standard?

I strongly support the proposed bill in Moore requiring all new homes to have a storm shelter or safe room, and I hope OKC and Edmond get on board with that soon as well.

Why though, in tornado alley, are most structures not built with tornadoes in mind?

[venture]

Simple - Cost. People don't want to pay for it.

[Jake]

Schools should seriously be looked into to be built to a higher standard, but like venture said, people don't want to pay for it.

As I was reading comments about the tornadoes on various news websites I noticed a lot of people asking, "why don't people construct their houses to withstand tornado strength winds? There should be a bill requiring homes to be built in order to withstand 200 mph winds." Which of course I thought was pretty funny.

For the cost of building my house into a bunker, I could just buy a storm shelter and spend the rest on tornado insurance.

[Ginkasa]

I'm not an architect or in construction so I may be way off, but I think the Warren's structural integrity is more a side product of sound-proofing the auditoriums and buildings in general. You might find the same with other movie theatres, or at least standalone ones. I do know the Harkins is considered one of the safer buildings in Bricktown.

I don't doubt there will be some research into incorporating some of those theatre design elements into at least portions of homes.

[Lindsay Architect]

I think most new schools are resolving this but a 40? year old building is another issue unless the school district has ran a bond issue for shelters. I thought the kids who died drowned in the basement? (Not sure on the facts of the situation but a basement is better than a safe room)
People need to resolve this with common sense and I'm sure that will happen and people will be happy to pay higher taxes for shelters, just don't turn it into MAPS4 or you'll get half the shelters half the size for double the money you were originally sold on.
But as far as laws and codes, should all houses and buildings be fire and flood proof?...in a perfect world. I think at least any school without a shelter should get a structural engineers letter on what they would say is the safest portion of the building for any worse case scenario. Luckily there weren't many more deaths.

[BoulderSooner]

It didn't take a direct hit

[kbsooner]

As a structural engineer, I can say without a doubt that the Warren is designed for code level winds. The code level wind load is based on a 90mph gust for 3 seconds at 33 feet in the air for Oklahoma. Based on the occupancy for the larger areas of the Warren, I bet that they had to up the importance factor based on increased risk factor, which puts another 15% onto the load based on a 90mph gust. This same increase in load applies for schools in modern building codes. You could attempt to design a full structure for a 200 mph wind load, but it will never be built due to cost.

So the Warren did probably take wind loads in excess of the wind load it was designed for. This can be attributed to safety factors that are applied in the steel and concrete codes when we design structures, so inherently there is additional strength in the components of the building. With this residual reserve capacities and the importance factor, it gave the Warren a fighting chance to withstand the brunt of the storm. Same goes to the Moore Medical Center. It may look worst for wear, but in reality it is really just the windows and cheap EIFS and studwork exterior that took the brunt of the damage. The framework of the building appears to be largely intact, and served it's purpose as it took a direct hit. But I will attribute the Warren's perforance in the storm to it's construction from concrete tilt walls (likely used for it's large span capacities and acoustical and insulating properties) and the type of connections inherent to that construction type. You can just look at all the light metal building type structures and see how they performed...

In reality, the biggest issue with structural collapse has to do with the interaction of the building's walls and roof system. The roof of the structures is treated as a diaphragm, which braces the tops of walls, collects loads as the lateral loads push on the walls and distributes it to shearwalls and frames that give a structure stability. I guess the easiest analogy I can think of is a cardboard box with a lid intact, which is pretty rigid, but remove the lid and the sides can be pushed and folded easily. In an extreme wind event, the speed of the wind over the top of the roof actually produces very high areas up uplift force on the roof surface, especially around corners and the sides of the roof. So if the roof connections to the support structure begin to fail, whether it be welds on a steel deck of nails on plywood, if it begins to lift off the structure at all, it allows wind to get underneath the deck and eventually start peeling away. If this happens on a large enough scale, then the entire roof diaphragm and wall bracing of a building is compromised, leaving walls without bracing or load paths to lateral load bracing elements and eventual collapse. So reality is a CMU wall may be designed for a 90mph gust, but could potentially withstand much more load without catastrophic collapse, but once the roof goes it doesn't have a chance.

[kbsooner]

I'm not an architect or in construction so I may be way off, but I think the Warren's structural integrity is more a side product of sound-proofing the auditoriums and buildings in general. You might find the same with other movie theatres, or at least standalone ones. I do know the Harkins is considered one of the safer buildings in Bricktown.

I don't doubt there will be some research into incorporating some of those theatre design elements into at least portions of homes.

They have, they are concrete safe rooms.

[bchris02]

Safe rooms and storm shelters are adequate for homes, but there's no doubt public buildings such as schools and hospitals should be built to withstand a tornado hit. Same goes for high density housing that gets built in the urban core.

[CuatrodeMayo]

As a structural engineer, I can say without a doubt that the Warren is designed for code level winds. The code level wind load is based on a 90mph gust for 3 seconds at 33 feet in the air for Oklahoma. Based on the occupancy for the larger areas of the Warren, I bet that they had to up the importance factor based on increased risk factor, which puts another 15% onto the load based on a 90mph gust. This same increase in load applies for schools in modern building codes. You could attempt to design a full structure for a 200 mph wind load, but it will never be built due to cost.

So the Warren did probably take wind loads in excess of the wind load it was designed for. This can be attributed to safety factors that are applied in the steel and concrete codes when we design structures, so inherently there is additional strength in the components of the building. With this residual reserve capacities and the importance factor, it gave the Warren a fighting chance to withstand the brunt of the storm. Same goes to the Moore Medical Center. It may look worst for wear, but in reality it is really just the windows and cheap EIFS and studwork exterior that took the brunt of the damage. The framework of the building appears to be largely intact, and served it's purpose as it took a direct hit. But I will attribute the Warren's perforance in the storm to it's construction from concrete tilt walls (likely used for it's large span capacities and acoustical and insulating properties) and the type of connections inherent to that construction type. You can just look at all the light metal building type structures and see how they performed...

In reality, the biggest issue with structural collapse has to do with the interaction of the building's walls and roof system. The roof of the structures is treated as a diaphragm, which braces the tops of walls, collects loads as the lateral loads push on the walls and distributes it to shearwalls and frames that give a structure stability. I guess the easiest analogy I can think of is a cardboard box with a lid intact, which is pretty rigid, but remove the lid and the sides can be pushed and folded easily. In an extreme wind event, the speed of the wind over the top of the roof actually produces very high areas up uplift force on the roof surface, especially around corners and the sides of the roof. So if the roof connections to the support structure begin to fail, whether it be welds on a steel deck of nails on plywood, if it begins to lift off the structure at all, it allows wind to get underneath the deck and eventually start peeling away. If this happens on a large enough scale, then the entire roof diaphragm and wall bracing of a building is compromised, leaving walls without bracing or load paths to lateral load bracing elements and eventual collapse. So reality is a CMU wall may be designed for a 90mph gust, but could potentially withstand much more load without catastrophic collapse, but once the roof goes it doesn't have a chance.

Exactly correct. Thanks for taking the time to post this.

[kbsooner]

Safe rooms and storm shelters are adequate for homes, but there's no doubt public buildings such as schools and hospitals should be built to withstand a tornado hit. Same goes for high density housing that gets built in the urban core.

This maybe callous, but it frankly will never happen for an entire structure. It would just cost way too much. That's why they have saferooms, so they can isolate the cost into a smaller refuge area. One caveat that raises cost is the code states you have to have 5 sq ft per person in a safe room. So for a elementary school of 500, that's at least 2500 sq ft, probably more to account for handicap access etc.

Actually, I found this arcticle ( http://www.pci.org/view_file.cfm?file=AS-11SU-7.pdf ) and it really spells out the process really well including all the code issues that we face. It states: Many factors influence the cost of a safe room. Key factors include number of uses, design simplicity, windspeed design, debris-impact criteria, exterior wall and roof materials, and location with regard to foundation and site-development requirements. Costs generally range from $150-$240 per square foot, depending on geographic location and the secondary use. So these rooms can be built into a new school for a price, and I agree they should be. But this cost is going into a large overall project so the isolated price spike can be absorbed into the larger pricetag of the entire structure. But retrofitting all the schools in a district would be a large financial undertaking. Still it should be put to a bond vote to add these structures.

[kbsooner]

In reality, the biggest issue with structural collapse has to do with the interaction of the building's walls and roof system. The roof of the structures is treated as a diaphragm, which braces the tops of walls, collects loads as the lateral loads push on the walls and distributes it to shearwalls and frames that give a structure stability. I guess the easiest analogy I can think of is a cardboard box with a lid intact, which is pretty rigid, but remove the lid and the sides can be pushed and folded easily. In an extreme wind event, the speed of the wind over the top of the roof actually produces very high areas up uplift force on the roof surface, especially around corners and the sides of the roof. So if the roof connections to the support structure begin to fail, whether it be welds on a steel deck of nails on plywood, if it begins to lift off the structure at all, it allows wind to get underneath the deck and eventually start peeling away. If this happens on a large enough scale, then the entire roof diaphragm and wall bracing of a building is compromised, leaving walls without bracing or load paths to lateral load bracing elements and eventual collapse. So reality is a CMU wall may be designed for a 90mph gust, but could potentially withstand much more load without catastrophic collapse, but once the roof goes it doesn't have a chance.

Sorry to quote myself, but this above also applies to residential construction. If you can keep the roof on your home, you have a chance to avoid total collapse. If you are building a new home, you should insist on having hurricane clips installed from the trusses or roof rafters to the top plates of your walls. These framing elements are often toenailed in and have very little uplift capacity, and even less so when framers today work so quickly and haphazardly nail these elements down. These won't resist an hit from an F5, but would go a long way in helping save roofs in many high wind events.

[adaniel]

It didn't take a direct hit

Kind of surprised this was skipped over. I don't want to take anything away from Bill Warren who has been nothing but class, but looking at the Google crisis map shows this to be true. The homes directly across from the Warren are still standing with minimal damage.

Google Crisis Map

[Anonymous.]

Yea, the tornado went north of the Warren, it did not pass over it.

[David]

Excellent posts KB.

[OKCTalker]

I've learned a great deal this week about the geological problems with installing in-ground storm shelters in Oklahoma. Subjects that seem simple usually aren't.

[venture]

I've learned a great deal this week about the geological problems with installing in-ground storm shelters in Oklahoma. Subjects that seem simple usually aren't.

There have also been a number of people coming forward that a lot of the obstacles people feel are against having basements are unfounded. A lot of it seems to come down to people not wanting to pay for it.

[jn1780]

There have also been a number of people coming forward that a lot of the obstacles people feel are against having basements are unfounded. A lot of it seems to come down to people not wanting to pay for it.

Basements are one thing, sure, waterproofing and maintaining a fullsize basement would be a pain, but sticking a waterproof box big enough for 5-6 people just below the surface isn't that hard to do.

[Urbanized]

There are some places where waterproofing might be a problem, but just as many or actually far more where it is not. There's more than one soil type in the metro. Also, while houses in low-lying areas might have hydraulic challenges, those in hillier parts of town likely will not. There are plenty of older homes with dry basements in this town. I used to own one in Gatewood built in 1927 which stayed totally dry and required no heroics from the builder to do so. Overall, the "high water table" thing is a red herring. What probably happened is over years of re-telling - like kids sitting in a circle and whispering a story into each others' ears - the real reason became obscured and misinterpreted by the re-tellers.

The REAL reason we don't have many basements these days is because of our relatively warm climate. Follow me here: because our frost line is only about 18", shallow slab construction is practical (and MUCH cheaper). When poured-slab construction became the norm here (post-1950s), deep stem wall foundations became a rarity. In colder climates, builders might have to go 4' or 6' deep with a stem wall & excavate crawl spaces for water lines and other utilities. As long as you are that deep already, a basement is almost free. At that point, a builder can get more value out of the home without much additional expense by adding one. When fewer and fewer homes in Oklahoma were built with basements as the poured slab trend took hold, there became fewer and fewer contractors who even knew how to build basements. If you were in the basement-building business you moved elsewhere or you found another business. Nowadays if you want one it is comparatively expensive for all of these reasons, so people just don't do them very often. THAT is the reason we don't have basements. Most of the other reasons you've heard are generally inaccurate.

[ou48A]

Sorry to quote myself, but this above also applies to residential construction. If you can keep the roof on your home, you have a chance to avoid total collapse. If you are building a new home, you should insist on having hurricane clips installed from the trusses or roof rafters to the top plates of your walls. These framing elements are often toenailed in and have very little uplift capacity, and even less so when framers today work so quickly and haphazardly nail these elements down. These won't resist an hit from an F5, but would go a long way in helping save roofs in many high wind events.

Very good information.

On the link below wind researchers have determined that for a fairly low cost homes can be made far stronger. The hurricane clip is one major part of the solution….But it might be better if we called them tornado clips in our part of the country. Stronger state building codes that require the use of cheap hurricane clips would be a simple solution to reduce damage, injury’s and death.

Texas Tech University :: Wind Science and Engineering Research Center

[LakeEffect]

There are some places where waterproofing might be a problem, but just as many or actually far more where it is not. There's more than one soil type in the metro. Also, while houses in low-lying areas might have hydraulic challenges, those in hillier parts of town likely will not. There are plenty of older homes with dry basements in this town. I used to own one in Gatewood built in 1927 which stayed totally dry and required no heroics from the builder to do so. Overall, the "high water table" thing is a red herring. What probably happened is over years of re-telling - like kids sitting in a circle and whispering a story into each others' years - the real reason became obscured and misinterpreted by the re-tellers.

The REAL reason we don't have many basements these days is because of our relatively warm climate. Follow me here: because our frost line is only about 18", shallow slab construction is practical (and MUCH cheaper). When poured-slab construction became the norm here (post-1950s), deep stem wall foundations became a rarity. In colder climates, builders might have to go 4' or 6' deep with a stem wall & excavate crawl spaces for water lines and other utilities. As long as you are that deep already, a basement is almost free. At that point, a builder can get more value out of the home without much additional expense by adding one. When fewer and fewer homes in Oklahoma were built with basements as the poured slab trend took hold, there became fewer and fewer contractors who even knew how to build basements. If you were in the basement-building business you moved elsewhere or you found another business. Nowadays if you want one it is comparatively expensive for all of these reasons, so people just don't do them very often. THAT is the reason we don't have basements. Most of the other reasons you've heard are generally inaccurate.

Very well said.

[Bunty]

Speaking of slab construction, I sure hope they do okay despite cracks that develop in them. In one new home under construction, I was surprised to spot a crack had already developed on it, and it extended clear across most of it.

[CuatrodeMayo]

Nothing unusual. Concrete is guaranteed to do two things: 1) get hard. 2) crack.

[bluedogok]

There are some places where waterproofing might be a problem, but just as many or actually far more where it is not. There's more than one soil type in the metro. Also, while houses in low-lying areas might have hydraulic challenges, those in hillier parts of town likely will not. There are plenty of older homes with dry basements in this town. I used to own one in Gatewood built in 1927 which stayed totally dry and required no heroics from the builder to do so. Overall, the "high water table" thing is a red herring. What probably happened is over years of re-telling - like kids sitting in a circle and whispering a story into each others' ears - the real reason became obscured and misinterpreted by the re-tellers.

The REAL reason we don't have many basements these days is because of our relatively warm climate. Follow me here: because our frost line is only about 18", shallow slab construction is practical (and MUCH cheaper). When poured-slab construction became the norm here (post-1950s), deep stem wall foundations became a rarity. In colder climates, builders might have to go 4' or 6' deep with a stem wall & excavate crawl spaces for water lines and other utilities. As long as you are that deep already, a basement is almost free. At that point, a builder can get more value out of the home without much additional expense by adding one. When fewer and fewer homes in Oklahoma were built with basements as the poured slab trend took hold, there became fewer and fewer contractors who even knew how to build basements. If you were in the basement-building business you moved elsewhere or you found another business. Nowadays if you want one it is comparatively expensive for all of these reasons, so people just don't do them very often. THAT is the reason we don't have basements. Most of the other reasons you've heard are generally inaccurate.

My great-grandfathers house was on NW 22nd & Robinson, the basement was a constant maintenance nightmare. Some areas could handle them at a reasonable cost but many areas can't without being built out at a very high cost. Concrete tilt-wall, precast or CMU type of construction will typically be able to withstand a whole lot more force than an EIFS/brick on metal stud type of construction if it is built right. To build a house to withstand a direct hit of an F5 is not realistic, you are talking about bomb bunker type construction because that is the type of physical force you are talking about, even commercial buildings are not built to that unless there are special circumstances (like the force protection built in the new federal building). No one is willing to spend that kind of money, a $100,000 house becomes a $750,000 house trying to enact something like that. Yes, houses could be built much better construction than the typical stick frame that is built today but it ultimately comes down to cost, most people would prefer to spend the money on granite countertops than better construction because they don't know any better and the home builders are building what they (and the banks) thinks will sell.

The basement in our house here in Aurora wouldn't be a very good shelter, the floor above is wood framed and could easily collapse on top of us in the kind of storm that hit Moore. You would have to build a basement like a safe room but then you have daylighting and fire exit code requirements which compromise the integrity of a basement in regards to structural integrity in a storm. Much of the problem is the in-fighting between the various groups that write codes, fire officials demand an exit and health people require natural lighting so you end up with a basement well and window large enough for a person to climb out of, the basements of old had no such requirements.

[Snowman]

There are some places where waterproofing might be a problem, but just as many or actually far more where it is not. There's more than one soil type in the metro. Also, while houses in low-lying areas might have hydraulic challenges, those in hillier parts of town likely will not. There are plenty of older homes with dry basements in this town. I used to own one in Gatewood built in 1927 which stayed totally dry and required no heroics from the builder to do so. Overall, the "high water table" thing is a red herring. What probably happened is over years of re-telling - like kids sitting in a circle and whispering a story into each others' ears - the real reason became obscured and misinterpreted by the re-tellers.

The REAL reason we don't have many basements these days is because of our relatively warm climate. Follow me here: because our frost line is only about 18", shallow slab construction is practical (and MUCH cheaper). When poured-slab construction became the norm here (post-1950s), deep stem wall foundations became a rarity. In colder climates, builders might have to go 4' or 6' deep with a stem wall & excavate crawl spaces for water lines and other utilities. As long as you are that deep already, a basement is almost free. At that point, a builder can get more value out of the home without much additional expense by adding one. When fewer and fewer homes in Oklahoma were built with basements as the poured slab trend took hold, there became fewer and fewer contractors who even knew how to build basements. If you were in the basement-building business you moved elsewhere or you found another business. Nowadays if you want one it is comparatively expensive for all of these reasons, so people just don't do them very often. THAT is the reason we don't have basements. Most of the other reasons you've heard are generally inaccurate.

It is not all myths. I knew about ten families with storm cellers within a one mile radius of where I grew up, all houses built in the late seventies/early eighties, they were all flooded. None less than a foot, one up to five feet. After my parents moved to there newest house, my dad found while digging that solid bedrock so shallow that he gave up on trying to putting in an in-ground basketball goal for my nieces and nephews.