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Hurricane Failure Modes: Gas Station Canopy Design

  • 1.  Hurricane Failure Modes: Gas Station Canopy Design

    Posted 08-30-2023 01:06 PM

    Saw an image of a gas station canopy toppled due to hurricane Idalia and damage to the structure and the pumps.

    It must be noted that I have never had the pleasure of researching and designing this type of structure. However, I have had to design structural assemblies that required a failure mechanism. 

    My first thought "there needs to be a designed failure mechanism that sacrifices a component, but keeps the structure intact during significant wind events."

    Note: There is actually some back and forth in my head as I think through this, so do not judge me. It is my process! LOL!

    Next thought (NT) 1: Fasteners or bolts where the overhead structure meets the posts. Pushback (PB) 1: Uncontrolled large flying structure. Too risky.[Additional thought-Chain it down so it only travels so far. PB to AT1: UNCONTROLLABLE. May create a loading scenario worse than uplift.)

    NT2: Fasteners, but save primary structure let panels release. PB2: See PB1

    NT3: Fasteners, with smaller panel sections. Let smaller sections go, nobody should be out in this weather. PB3: Still too risky, IMO.

    NT3: Fasteners at boundaries only with hinges that hold  Allow structural panels to give or let wind pass in the wind event. Gravity based loading carried in bearing. Flapping Panels. PB3: (Working on it).

    Note: Have not participated in a while due to work. Wanted to share my thoughts.

    Structural failures due to significant wind events

    James Williams P.E., M.ASCE
    POA&M Structural Engineering, PLC
    Yorktown, VA

  • 2.  RE: Hurricane Failure Modes: Gas Station Canopy Design

    Posted 08-31-2023 11:10 AM

    Interesting thoughts, but I agree with your PB concerns.  Any flying debris becomes problematic for downwind structures.  I used to design cell towers, and we had one fail during a hurricane.  Not because the tower couldn't handle the wind loads, but because of the failure of an upwind metal building.  The metal siding and/or roof panels hit our tower and stuck, turning a skeletal structure into a wall.  Sheared off the solid round bar legs of the tower.

    Brian Carlisle P.E., M.ASCE
    Professional Engineer
    Haughton LA