Are Miami high-rises in danger of collapsing in Cat 5 winds?

[zlaxier]

Actually, in the 1926 miami hurricane, a cat 4, the surge of 10 feet covered the entire island of Miami Beach and everything was flooded up to about 3 blocks on the mainland.

http://www.srh.noaa.gov/mfl/newpage/Mia ... icane.html

The worst part of the hurricane, with onshore southeasterly winds bringing a 10 foot storm surge onto Miami Beach and the barrier islands, began around 7 AM and continued the rest of the morning. At the height of the storm surge, the water from the Atlantic extended all the way across Miami Beach and Biscayne Bay into the City of Miami for several city blocks.

[zlaxier]

NOAA has a map on that webpage showing all of the areas that flooded from the storm surge in the 1926 hurricane.

[Recurve]

Great pictures and maps.

As many know, (then-) Burger King headquarters were near ground zero for surge and wind in Andrew, and it was gutted by waves to the second floor at least (a big, low building, second floor may have been at 25' elevation on stilts, but I forget if it was more than two total stories).

How much surge is different off Miami Beach is a great question.

I heard someone say last week that people here think the shallows off Islamorada cause worse surge than Key Largo would get because of the Hawk Channel "trench" behind the reef. i have no idea if that's just crazy conjecture and wishful thinking.

Some buildings survived surge from Donna near the middle Keys, and I guess that would be because the coral substrate here really doesn't move like the Miami Beach sand and fill would. A few modest highrises have gone up in the middle Keys since Donna. Some have had major problems from the environment and salty concrete even. I hope they don't ever become a tragic example of how collapse is possible on the coast.

[Ptarmigan]

a collapse in a hurricane of a high rise may be far worse than the 9/11

The WTC collapsed downward. If the Katrina NWS advisory were to come true, the high rise may tip over. That is basically an oversized cruise missle hitting the center of the city

I thought it is physically impossible for a high-rise to tip over. Maybe I am wrong.

[vmax135]

Hi Everyone - Here are some additional damage shots from the 1926 Miami Hurricane that I thought everyone might find interesting, given the specific topic...

This is a shot (looking NE... those familiar with the Miami skyline will recognize the Miami News tower, later called the 'Freedom' tower, in the background.) at what was the 17-story Meyer-Kiser building in downtown Miami. The building was built in 1925 and, at the time, was one of Miami's tallest. Less than a year after being completed, it sustained severe wind damage in the 1926 storm with significant shear and interior wall failures. After the storm, engineering assements determined that the building's framework had been so severely distorted by the winds, that the upper 10-floors of the structure had to be torn down... they were never rebuilt. Today, the remaining 7-stories (plus three new floors) are still located at: 139 NE 1st Street and are known as the "Dade Commonwealth Building."




Here is a close-up shot of a heavily damaged portion of the Meyer-Kiser building...



Here are some other notable damage shots from Miami, and the surrounding area, after the 1926 storm:

Both the north and south approaches to the Baker's Haulover bridge, near Aventura (North Miami Beach) were washed out. This view is looking east towards the Atlantic from the south side of the inlet.



This image has alternately been listed as Coral Gables or Hialeah (though with the style of the home, I suspect it is Coral Gables) and shows severe wind damage to a two-story private residence.



Here is the cover of the 'Miami Daily News' the morning after the storm...


For those interested in reading a much more detailed account of the 1926 storm (including a separate article with a great analysis of the wind readings obtained during the storm from the old Allison Hospital on Miami Beach (250 W 63rd Street), here is a link to a PDF of the October 1926 edition of the Monthly Weather Review... (the articles start on page 5).

http://www.tropmet.com/gallery/1926.pdf


-=Michael=-
http://www.tropmet.com

[windstorm99]

Micheal ive read that PDF on the 1926 miami hurricane and and its content is very interesting.

Great damage pics!

[DanKellFla]

a collapse in a hurricane of a high rise may be far worse than the 9/11

The WTC collapsed downward. If the Katrina NWS advisory were to come true, the high rise may tip over. That is basically an oversized cruise missle hitting the center of the city

I thought it is physically impossible for a high-rise to tip over. Maybe I am wrong.

The WTC building was of an atypical design. It carried most of its weight in the perimeter of the building. Think of a soda can. Typically, high-rises are built with steel skeletons. For this reason, it is unlikely a high-rise would tip over from wind. The windows and interior walls would probably give way before the steel did.


As for high-rises tipping over, have you ever watched buildings being imploded. Sometimes, the building is aimed to fall away from some other structure. It is pretty cool.

[windstorm99]

Here are some synoptic charts from the 1926 miami hurricane...

[Derek Ortt]

I may be mistaken (not an engineer, so if anyone is, please correct me), if a high rise sways too much, it will come down.

I just hope we never find out just how much a highrise can sway before collapse

[Dionne]

Notice in the pics in this thread and others......concrete structures with radius designs seem to have stood while those without failed. Although, it doesn't matter much if your entire structure is gutted.

[DanKellFla]

I may be mistaken (not an engineer, so if anyone is, please correct me), if a high rise sways too much, it will come down.

I just hope we never find out just how much a highrise can sway before collapse

You are correct. Earthquakes can cause that kind of failure mode in a tall building. It is highly unlikely that a wind load could cause that kind of failure because other failures would happen first. Windows, doors and walls would be blown out which would then allow the wind to pass through. Also, tall buildings have a frequency that they sway at, and a frequency where shedding vorticies happens. If done correctly, those frequencies are very far apart. (Google Galloping Gurtie to see it done incorrectly.) Of course, once window, doors and walls are gone, there is a lot of work to make the building useful again.


No, I didn't stay in a Holiday Inn Express last night, but I am a Mechanical Engineer.

[DanKellFla]

50 posts about an interesting topic, and I have to be the one to kill the thread.

[vmax135]

50 posts about an interesting topic, and I have to be the one to kill the thread.

Hahaha... I don't think you killed it? Just tucked it in for a little nap. J/K

Actually, I agree with all your comments. Though I personally would never completely rule out the "possibility" that a high-rise could collapse from a "worst-case" wind load scenario alone, I think the probablity of that happening is extremely slight... and would likely take a very complex set of circumstances. And like you said, even if the building doesn't collapse, the resulting interior damage from walls, windows and doors failing would be tremendous in and of itself (i.e. the Burger King World Headquarters after Andrew)

That said, in a hypothetical "worst case" hurricane scenario for downtown Miami, I also agree with the pemise that other types of damage may occur which could potentially augment and/or expedite a catastrophic failure of a high-rise... i.e. If one (or potentially multiple) of the massive construction cranes that are currently everywhere throughout the downtown area were to collapse and strike a nearby building, I can only assume that an impact (or impacts) of that magnitude could be enough to weaken load-bearing elements of the structure to the point that, when combined with the extreme wind loads, the building (or a good portion of it) might fail. That collapse could then potentially lead to other catastrophic failures in nearby buildings.

In addition, aside from the wind-load... some of the Miami area high-rises have other factors to contend with. I remember a documentary on Channel 10 back in 1979 interviewing Neil Frank, Herb Saffir and others about a catastrophic hurricane scenario in Miami (almost prophetic when David approached later that summer) and, at that time, they were very concerned about several condos that had been constructed on "compressed sand" pilings, adjacent to the beach, on Key Biscayne. If I remember correctly, they were concerned that significant erosion would occur, allowing the "compressed sand" to be exposed and also eroded, ultimately allowing the building to be undermined and collapse. I don't remember the specific development that they used as a case study... and I guess it's possible that the buildings have since been retrofitted (though I doubt it), but I suspect this type of scenario would potentially produce a greater risk for seeing large buildings collapse, than from wind loads alone.

Actually a lot of the discussion I've seen for "worst-case scenarios", in threads and in the media, tend to deal with a single city being impacted... i.e. It Could Happen Tomorrow: A Category Five Striking <<fill in your city here>>. My personal opinion is that thinking of a single city as a "worst-case" scenario is too narrow in potential scope... the worst-case scenario for South Florida wouldn't actually be a direct strike on any one particular city, but on several. Like what would happen with a relatively slow-moving, annular, category five, with a huge inner core and windfield... (something like Isabel at it's peak)... taking a track like Cleo in 1964... coming onshore over downtown Miami, moving north-northwest, almost paralleling the Florida east coast with enough of the inner core remaining over water to slow the weakening process, while both sides of the eyewall rake Miami, Miami Beach, Ft.Lauderdale, Boca, Delray, West Palm and everything in between... during multiple tidal cycles... with the western eyewall moving directly over Lake Okeechobee (assuming there's any water left in it after this summer). The results would be unimaginable.

-=Michael=-
http://www.tropmet.com

[Derek Ortt]

I would say Wilma 10miles to the south would be the worst case.

Get another 20% evac rate from Key West, but instead of putting 7 feet of surge, put the full 15-20 from a direct hit and we would have a repeat of Galveston. Potentially came very close that terrible Monday morning. That, along with the destruction in the metro areas and the Lake

[vmax135]

I would say Wilma 10miles to the south would be the worst case.

Get another 20% evac rate from Key West, but instead of putting 7 feet of surge, put the full 15-20 from a direct hit and we would have a repeat of Galveston. Potentially came very close that terrible Monday morning. That, along with the destruction in the metro areas and the Lake

Yep, a monster-sized... "doomsday" intensity storm... on a NE track... coming in just north of Key West... exiting near the Broward/Palm Beach line... with a lackluster evacuation... would be another nightmare scenario.

-=Michael=-
http://www.tropmet.com

[Dionne]

It can always get worse. Remember March 27, 1964? It wasn't a hurricane. The ground went into the rock and roll mode for a little over 5 minutes then the water came in.....the water would come in and go back out....repeatedly all through the night. Buildings collapsed, people died from both falling debris and water. Similar to Katrina.....people lost everything. It was my first lesson with fear. The Great Alaskan earthquake. Two large scale natural disasters in one lifetime is enough!