Hurricane Michael

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Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

  • 1.  Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-11-2018 13:25

    Just within about 3 weeks time – a different experience and perspective – not only in the locations of landfall, but also in the characteristics of two different hurricanes. While the September 13th Hurricane Florence was like a nasty sluggish monster – yesterday's Hurricane Michael was like a heroic monster in its wind power and storm surge. The former showed the power of relentless rainfall poured by a weak crawling storm. The latter is an example of the power of very high sustained wind speed of a fast-moving hurricane – let us say, in its grandeur like the utterance of Julius Caesar: Veni Vidi Vici.

    We can describe both the storms in all different attractive terms in an attempt to make a serious subject lighter – but the misery of the affected people, damages and destruction are very real and painful. We feel their pain deeply and our thoughts and prayers are for the victims. Fortunately for the Florida Panhandle region however, the piling of storm surge by the landfalling (October 10th, 13:30 ET) Hurricane Michael came about 2 hours before the high tide (at about 15:10 ET at Apalachicola). This time-difference has likely abated the peak surge somewhat – yet strong enough to cause extensive coastal flooding with the surge force uplifting and carrying boats, homes, cars and debris like toys.

    We will know more about the trail of destructions inflicted by Hurricane Michael in its trajectory in the coming days. It will be interesting – and we invite all to share insights and experiences of this latest monster near the end of hurricane season.

    ------------------------------
    Dr. Dilip Barua, Ph.D, P.Eng, M. ASCE
    Vancouver, BC, Canada
    Website: https://widecanvas.weebly.com
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  • 2.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-12-2018 10:05
    Dr. Barua,

    Excellent article. I couldn't agree more, just yesterday I published some thoughts about the initial assessed Hurricane Michael aftermath. Below the link:

    Was not supposed to be a Cat 4-5!
    Linkedin remove preview
    Was not supposed to be a Cat 4-5!
    Denying climate change regardless whatever the cause, is just naive. Temperatures will continue to rise, ocean waters will get warmer, hurricanes will become more frequent, bigger and stronger.
    View this on Linkedin >


    Let's continue the conversation, comment and get the best of us in these sad times.

    Regards,





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    Raul Hinojosa Ing., M.ASCE
    Structural Engineer
    Orlando, FL
    https://www.linkedin.com/in/raul-hinojosa-4319407b/
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  • 3.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-13-2018 09:19
    Although I have not visited the site, from the photographs and videos on the media, ​I note stark similarities in the destruction caused by Hurricane Andrew in South Dade in August 1992 and Hurricane Michael that just passed thru Florida panhandle. Hurricane Andrew inflicted damages to structures in its path, but wood framed homes and homes with wood gable ends sitting on flat concrete beams and prefabricated metal buildings sustained much more damages. Many wood framed homes in Country Walk and metal buildings in Homestead and Florida City collapsed. Similar damages are seen in the Florida panhandle where wood framed construction and prefabricated metal building construction appear to be more common.

    in the aftermath of Hurricane Andrew, then applicable South Florida Building Code was strengthened, most of the revisions originated from my office, based upon data collected and presented in ten (10) volumes I produced on design and construction deficiencies of pre-Andrew construction. Tougher standards were adopted for fenestrations. I also presented a paper on the subject in ASCE conference on Hurricanes of 1992, held in Miami, December 1993. A paper on performance of precast prestressed concrete double tees was also published in ASCE Journal of Performance of Construction Facilities, Vol. 8, No 1, Feb. 1884.

    When Florida Building Code came into being, the beefed up requirements of the South Florida Building Code were not adopted for entire Florida and if it were not the efforts of Dade, Broward and Palm Beach county's building officials, those requirements would have vanished altogether. Efforts of these officials resulted in the insertion of a "code within the code", called " High Velocity Hurricane Zone, HVHZ", applicable only in Dade, Broward, Monroe and Palm Beach counties of the State of Florida. Code writers and users elsewhere refused to recognize that other coastal areas of the State of Florida were as vulnerable to hurricanes as the four counties using HVHZ provisions of the code and Hurricane Michael just proven them to be wrong.

    So, will the rest of the coastal counties of the State of Florida heed and adopt HVHZ provisions of the Florida Building Code or will they continue to "stick their heads in sand, like ostriches do?".



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    Mohammad Khan M.ASCE
    KHAN AND ASSOCIATES, INC.
    Miami FL
    (305) 498-8370
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  • 4.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-13-2018 12:03
    I just saw this article with further background to the question posed by Mohammad.

    Florida building code left Panhandle vulnerable to big storms | Miami Herald
    miamiherald remove preview
    Florida building code left Panhandle vulnerable to big storms | Miami Herald
    The devastation wrought by Hurricane Michael may have exposed a weak spot in Florida's lauded statewide building code, among the strongest anywhere when it comes to windstorms: Across much of the Panhandle, the rules may not be tough enough. That's because the code's requirements for wind resistance vary widely by location.
    View this on miamiherald >


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    Tom Chase, M.ASCE
    Director, COPRI of ASCE
    Reston VA
    (703)295-6027
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  • 5.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-14-2018 09:02
    It's long been rumored among FL GC's that the wind zone map was crafted for reduced mandatory minimums in the panhandle largely due to its relation to Tallahassee and cheaper beachfront property for those in the capital. For instance, one can live an hour inland near Orlando and have the same wind speed requirements as a coastal structure in the panhandle. Whereas the coastal requirements in frequently impacted areas such as Miami and the east coast are significantly higher standards. This makes sense given the probability of loss vs. the cost of stricter regulations.

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    Jesse Kamm PhD, PMP, A.M.ASCE
    Vice President of Construction Management
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  • 6.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-15-2018 08:01
    Doubtful about the wind map conspiracy.  The maps in the FBC match ASCE 7-10 for wind velocity.  What was monkeyed with was the wind-borne debris zones.

    From what I have seen from photos is that the very near coastal damage was from flood surge.  The roofs that were lost on PEMB's may have been older ones (say pre-1995) that did not meet the current design and testing for metal roofs.  What was concerning was the damage to the HS gym in Panama City.  It looks like a masonry end wall blew in, and that changed the building from enclosed to partially enclosed.  QED.

    I am not surprised at the damages at Tyndall AFB.  The military keeps old buildings well beyond their lifespan because there just is never enough money to keep up with replacements.  As an example, when I was in the Army in the mid-80's, I was designing renovations to WW2 mobilization structures that were over 40 years old.  And many, if not most, are still in service now at 78 years old.

    This was THE design hurricane with design wind pressures.  So I am not surprised at damage for a few reasons.  (1)  Losing older roofs that did not meet newer design standards.  (2)  Just plain design errors causing weak links in the load path.  (3)  Construction errors, not that we never see that otherwise.

    Hurricane Katrina in 2005 caused a lot of component and cladding damage in new structures in South Florida that were built to new codes.  And this storm was just barely a hurricane when it made landfall and well below the design storm.  Why the damage???  Numbers (2) and (3).   Those are not code problems, those are enforcement problems that cannot be solved by any code changes.

    What will be interesting is to look at what is still standing with minimal damage and why it survived.

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    Thomas Sputo Ph.D., P.E., F.ASCE, F.SEI
    Structural Engineer
    Gainesville FL
    (352) 372-8351
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  • 7.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-17-2018 10:13
    ​I agree with Dr. Sputo, who was my steel professor when I was studying at UF, some of the photos I have seen show some of the newer buildings still standing. These were likely designed with the newer codes such us the Coastal Construction Manual FEMA 55 and included a design flood elevation. When designing for storms especially on or close to the coast, you must account for the flood loads along with the wind. Most of the structures at ground level likely did not account for this.

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    Jason Gowland P.E., M.ASCE
    Senior Engineer
    GSE Engineering
    Williston FL
    (352) 486-1197
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  • 8.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-18-2018 10:11
    I think the word "conspiracy" is unnecessary. It's fair criticism to suggest outside influences, cognitive biases, economics, cost vs benefits, and the like influence these regulatory decisions. We see it everyday with gerrymandering in politics, value engineering decisions, unwise scope reductions etc. I'm simply saying that when the mandatory minimums were released, many FL GC's took notice of the reduced coastal requirements in the panhandle and wondered about the logic. Since GC's are primarily concerned with costs and methods, those were obvious discussion points. It's no secret that added bureaucracy make working in Miami-Dade or other coastal regions more burdensome for GCs compared to other regions around the US. I do work all over the US and it's truly mindblowing how little regulations some states have and how strict others are. The FL construction community as a whole have become pretty good at making the economics work and our structures are undoubtedly safer than pre-hurricane Andrew, but the economics and regulations go hand-in-hand.

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    Jesse Kamm PhD, PMP, A.M.ASCE
    Vice President of Construction Management
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  • 9.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-18-2018 13:38
    The collapse of the school gymnasium end wall at Mexico Beach is very concerning to me for the reason that many counties look to utilize gymnasiums as hurricane evacuation shelters because they can accommodate a large number of people and can reduce their shelter deficit more readily. However, long span, light weight roof systems and tall walls typical of gymnasium construction are by their nature not best suited for resisting high wind loads. Obvious better choices for shelter locations would be smaller interior rooms, but they are not able to hold as many people. My understanding is that hurricane evacuation shelters in Florida are selected based on ARC 4496 Least Risk Decision Making (LRDM) process which gives higher priority to buildings that were certified to have been designed to meet the current building code at the time they were constructed. My understanding is that LRDM does not prevent spaces that have not been designed to such standards from being selected as shelters, it just ranks them lower on the list. Hence my concern that when gymnasiums, in particular, are designated as shelters, the spaces may not be as safe as the are perceived to be when given the name "shelter."

    It is my opinion that the ARC 4496 LRDM process can be, and should be improved upon, or revamped to provide a higher degree of safety for evacuation shelters than it currently does. Any engineer that has ranked buildings based on ARC 4496 LRDM process would likely take pause at the prescriptive method of evaluation. I am a strong advocate of the state's Enhanced Hurricane Protection Area criteria which requires a percentage of new school construction to have shelter areas designed in accordance with ICC 500. Perhaps we could move closer to this standard when selecting shelters.

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    Gregory Wayland P.E., M.ASCE
    Engr
    Gainesville FL
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  • 10.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-18-2018 11:43
    A few times in my 25+ years of practice, I'd been asked by some owners to "design for Category 5 hurricane". My answers were something like "I don't know what that means. I will design to meet the code." Sometimes, I'll offer to design for Category III/IV structures based on the code. The reason is that I don't know how the wind speeds reported by the weather service corresponds to the 3-sec wind gusts used in the codes. Category 5 hurricane can be anything above 156 mph reported by weather service. To the best of my understanding, the weather service estimates the near surface sustained winds based on flight level winds measured by the hurricane hunter. I am sure it is way more complex than that.

    This brings us to the "wind map" conspiracy. The wind map for category II buildings show the ultimate wind speed of 135 mph for the Panama City/Mexico Beach area (half way between 130 mph and 140 mph lines). For the Cat III/IV structures, it is 145 mph. This is the 3 sec. gust at 33 ft above ground. If we assume for this discussion purposes that this is same as the weather service reported winds, the 155 mph wind exceeded the 1700 year MRI winds by a full 10 mph! The MRI for this wind speed exceedance could be well above 4000 years. Perhaps this was such a rare event. Perhaps this is a trend from global warming. It is worth noting that these are 'Ultimate' wind speeds and when there is an event that exceed these speeds, there are no safety factors in the structural design. Increase of wind speed from 135 to 155 mph result in an increase of 32% in wind pressures. Failure is likely even if the structure is designed to meet codes.

    The latest data would have to be included in the statistical analysis and wind speed maps need to be updated. I am sure the discussions will continue about bringing back the 2007 FBC like wind-borne debris map again for entire state of Florida. Other gulf and Atlantic coastal states need to join.

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    Sivananthan Sritharan P.E., M.ASCE
    President
    S & F Engineers Inc
    FT LAUDERDALE FL

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  • 11.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-18-2018 14:32
    I have been a structural and forensic engineer in Florida since 1999 (my whole career). When the 2001 Florida Building Code was released, many engineers scratched their heads at the Chapter 16 Wind Maps, specifically the windborne debris region exceptions in the Panhandle. It was a very popular rumor that Tallahassee politicians were involved with this, and I am not a conspiracy theorist type, but politicians do have influence so it is quite possible in my opinion. The popular rumor that it was not only construction lobbyists, but also because many of the politicians had beachfront homes in these areas or other business interests that supposedly would have been affected.

    2004 FBC, Go to Chapter 16, hopefully this link works:
    CHAPTER 16 - STRUCTURAL LOADS | 2001 Florida Codes 2001 - Building (2nd Edition) | ICC premiumACCESS

    The 2007 FBC changed all of this, and the entire coastline of Florida became a windborne debris region, and in the Panhandle this zone pushed relatively far inland.
    2007 FBC:
    https://codes.iccsafe.org/content/chapter/3113/

    If it was a conspiracy, it was short lived. But to break it down a little further, to what gain would builders really have if they had to install impact resistant doors and windows or storm shudders on all new houses in certain regions (the main difference in designing a structure in a windborne debris region)? Would it cost more- of course. But if it was a requirement for everyone, it would be an even playing field for all contractors. Everyone's costs would go up , and that would be passed on to the owner. It would be like car manufacturers complaining about the cost of requiring air bags, it is fair if everyone has to do it.  I also do not think the average owner of property near a coastline would mind the extra money to not have to worry about putting plywood up over their windows, and would consider it a good investment in the integrity of their home. You also get insurance discounts, not to mention a much stronger, quieter, and all around better window. I just cannot see this much fuss over something that would likely not increase the cost of a beachfront home by more than a few percent if that. And for what it is worth, in my experience as a forensic engineer investigating hundreds of structures with wind damage, and reading FEMA and other post-disaster reports, I do not know of a lot of structural failures that were the direct result of windborne debris damage (though I understand and accept the idea of a breach causing an enclosed building to become partially enclosed, increased interior air pressure, etc.).

    I agree with Dr. Sputo's three reasons why there was so much wind damage. I would add specifically I know that region has a lot of older wood-framed homes, most with little if any uplift connections. Unfortunately what everyone is now clearly seeing is that we were right to improve the codes and make things stricter. It will be interesting to see what was storm surge damage and what was wind, and sometimes it is both. I have been involved with many "wind versus wave" investigations and they can be quite difficult, many times you are analyzing debris, pictures, and sometimes only a bare slab that is left. I should have the opportunity to have some boots on the ground experience in that area in upcoming months, so hopefully I can see first hand. It is all a painful and sad lesson on why we need to keep improving codes, design and enforcement.

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    Andrew Kester, PE
    Structural & Forensic Engineer
    KSE, LLC
    DeLand, Florida
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  • 12.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-15-2018 09:48
    What Mohammad has said at the end of the last paragraph is true.  While working for the City of Tamarac when the Code was being revised, the staff was asked to provide its feedback.  I distinctly remember asking the same question - how do you know that the same intensity storms would not strike elsewhere (outside the tri-County area) is Florida?  There was no convincing answer from the policy makers.  Recent years have shown that these hurricanes can drift/strike anywhere!  Thanks!

    Raj Verma, PE, M. ASCE
    Total Municipal Solutions
    Davie FL 33328


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    Rajesh Verma P.E., M.ASCE
    President
    Raj Verma Consulting, Inc.
    Davie FL
    (954)448-9056
    ------------------------------



  • 13.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-16-2018 16:48

    Mr. Khan –

    The following sentence in your 10-13-2018 ASCE Collaborate article caught my attention:

     

    "Efforts of these officials resulted in the insertion of a "code within the code," called " High Velocity Hurricane Zone, HVHZ", applicable only in Dade, Broward, Monroe and Palm Beach counties of the State of Florida."

     

    Just wanted to point out that per the FBC, the HVHZ has always consisted of only two counties: Broward and Miami-Dade. If there is some other source that I am not aware of that incorporates Palm Beach County and Monroe County in the HVHZ, please let me know.

     

    Thanks –

    Mark Fairchild, P.E.

    Licensed in FL, GA, TX

     

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  • 14.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-13-2018 09:19
    In my lifetime I had lived through five major hurricanes since the 60's, including Andrews (1992) when living and working in South Florida.  The 90's was a specially active decade in Hurricanes for Florida, and I remember discussing with friends and colleagues the house construction systems, specially in a time when great homes communities were being developed.

    Being a Caribbean native (D.R.), I knew for experience, and then as a practicing structural engineer, that houses built with wood, and mostly, roofs made out of weak nailed trusses with equally nailed plywood diaphragms did not have a chance against a CAT-3 or above hurricane.  Sometimes even a CAT-2 could do great damage.    I remember clearly Andrews devastation in Homestead (South of Miami), I lived at what it seemed to be at the time the "north street border" of the biggest destruction, in the only three (3) story concrete condo of the area.   We went harmless.  Everything else around was flatted.

    My major surprise was when they started re-building exactly the same way the obliterated houses were built before.  And again, and again and again, to these days.    Back in the time I recall that after a lot of of discussions, meetings, and "studies" for a Construction Code reform, the greatest results were throwing in a few extra steel plates and bolts.  And forbidding the use of the infamous staples frequently used also for... attaching roof diaphragms!!

    I still don't understand (well, I have a pretty close idea) why they insists on this construction method.  Same for the central states where they suffer tornadoes, sometimes worst, because they form suddenly without much time for preventive measures like hurricanes, that can be tracked for days, even weeks.    It's hard for me to think on economics reasons in a country like U.S.

    In my country, where I actually live and practice, upon returning many years ago already, nobody even considers or whatsoever building a house (or anything important for that matter) with structural wood.   At the most you can have small secondary,  constructions -open, most of them- like gazebos, canopies, architectural decorative attachments, or backyard shacks for home leisure.  But always conscious that in face of a hurricane those structures will fly.

    It is my opinion that the State of Florida should have a serious discussion about home building codes.   Wood studs second floor exterior load bearing walls, wood trusses/rafters and nailed (or worst, stapled) plywood diaphragms will have little or no chance at all against 90+ MPH sustained winds.   No matter what our nice and elegant computer (or hand, if you like) calculations say.   RC, CMU, steel and rigid diaphragms are the best materials at hand (so far, of course) to protect lives and homes, specially in places like Florida where there is no seismic threat, and wind it's their only concern.




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    Ramses Sanchez Aff.M.ASCE
    Structural Engineer
    Santo Domingo, Dominican Republic

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  • 15.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-14-2018 22:06

    Well said @Ramses Sanchez . I've grown and raised in the Caribbean as well like you (Dominican Republic), and despite being a third world country ​​​​it is clear that Reinforced Concrete is the way to go. Personally the Eye of Hurricane George CAT 4 almost CAT 5 pass by my town and absolutely nothing happen to my house.


    I understand the lobbism of the wood industry in the U.S. but seems like we as engineers are looking for an excuse to make wood construction better instead of cut to the chase and use concrete for everything, not only the foundation but walls, floors and more importantly the ROOF.

    The technology is there to analyze and design any type of concrete construction and the materials as well. Now it is doable and aesthetic is not a problem, because you can do concrete roofs any shape, pitch, form, in fact the more folded the better. A monolithic structure is the solution. I have been doing hundreds of those concrete roofs and concrete shell structures structural designs in the U.S. for various residences and affordable housing as well and it is possible and the ROI is very fast, sometimes less than 5 years and after that it's all savings. Really there is not an excuse, it is up to us to move ahead and lead by example, the solutions are out there waving at us since a long time ago.



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    Raul Hinojosa Ing., M.ASCE
    Structural Engineer
    Miami/Orlando FL
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  • 16.  RE: Hurricane Michael – Hope the Last One of the 2018 Hurricane Season

    Posted 10-15-2018 09:48
    ​Here's an article that speaks to the point of construction type for hurricane resistance.

    Among the Ruins of Mexico Beach Stands One House, Built 'For the Big One'
    Nytimes remove preview
    Among the Ruins of Mexico Beach Stands One House, Built 'For the Big One'
    MEXICO BEACH, Fla. - As they built their dream house last year on the shimmering sands of the Gulf of Mexico, Russell King and his nephew, Dr. Lebron Lackey, painstakingly documented every detail of the elevated construction, from the 40-foot pilings buried into the ground to the types of screws drilled into the walls.
    View this on Nytimes >


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    Robert Smith P.E., M.ASCE
    Senior Project Engineer
    Stantec
    West Palm Beach FL
    (561)209-7460
    ------------------------------