LearningAlways
Structural
- Aug 17, 2014
- 69
Hello,
I am a structural engineer. This is the first time I've worked on a building within a flood zone. I'm in Florida and the building we are looking at is in an AE zone with a static BFE of 12'.
The definition of the BFE on the FEMA map I am looking at is "A Base Flood Elevation is the expected elevation of flood water during the 1% annual chance storm event. Structures below the estimated water surface elevation may experience flooding during a base flood event."
The definition of the BFE in ASCE 24-14 is "Elevation of flooding, including wave height, having a 1% chance of being equaled or exceeded in any given year". Wave height is defined in ASCE as "vertical distance between the creast and the trough of a wave." Also in ASCE the Design Flood Elevation is "elevation of the design flood, including wave height, related to the datum specified on the community's flood hazard map." And depending on the structure the DFE is the BFE + 1 ft -or- what the AHJ has designated, whichever is higher.
Just to make sure, the BFE or DFE is not the still water depth, right? BFE/DFE is the flood elevation INCLUDING the wave height? The confusion comes when the FEMA map says static BFE. It just sounds like that would be the still water depth instead of the flooding elevation which includes wave height.
The Coastal Construction Manual has an image (attached) which confirms my hunch. But just to triple check I wanted to reach out to someone with more authority.
I am a structural engineer. This is the first time I've worked on a building within a flood zone. I'm in Florida and the building we are looking at is in an AE zone with a static BFE of 12'.
The definition of the BFE on the FEMA map I am looking at is "A Base Flood Elevation is the expected elevation of flood water during the 1% annual chance storm event. Structures below the estimated water surface elevation may experience flooding during a base flood event."
The definition of the BFE in ASCE 24-14 is "Elevation of flooding, including wave height, having a 1% chance of being equaled or exceeded in any given year". Wave height is defined in ASCE as "vertical distance between the creast and the trough of a wave." Also in ASCE the Design Flood Elevation is "elevation of the design flood, including wave height, related to the datum specified on the community's flood hazard map." And depending on the structure the DFE is the BFE + 1 ft -or- what the AHJ has designated, whichever is higher.
Just to make sure, the BFE or DFE is not the still water depth, right? BFE/DFE is the flood elevation INCLUDING the wave height? The confusion comes when the FEMA map says static BFE. It just sounds like that would be the still water depth instead of the flooding elevation which includes wave height.
The Coastal Construction Manual has an image (attached) which confirms my hunch. But just to triple check I wanted to reach out to someone with more authority.
