smoothed coastline AS/NZS 1170.2

[rowingengineer]

In AS/NZS 1170.2-2011 (and 2002) the regions B, C and D are given as distances from the smoothed coastline. 50,100,150 and 200 as defined in the Figure 3.19 (a).

My question is, how do you recreate the smoothed coastline?


ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[OzEng80]

With a Tsunami...

I interpret this as an 'average' distance from the coast within an arc of radius 50,100... It is meant to reflect the diminishing strength of a cyclone as it heads inland (as was poorly demonstrated by Yasi). Note that if i was on a threshold of a zone say +10-20kms i would probably design to the worst region anyway.

Off topic but the JCU cyclone testing station has released their report on Yasi. I found it a thoroughly interesting read!

http://www.jcu.edu.au/cts/public/groups/everyone/documents/technical_report/jcu_078421.pdf

 

[rscassar]

Good report, makes an interesting comment regarding the storm surge effect. Lucky the storm surge hit at low-tide otherwise there would be some serious water inundation. I guess this will need to be codified sometime in the future particularly if it is enhanced by the anticipated sea-level rise.

Has anyone who was experienced a category 5 cyclone noticed isolated tornado outbreaks during the cyclone??

 

[OzEng80]

I have spoken with numerous people who were holed up during Cyclone Yasi and Larry (both alleged 5's) all of whom were somewhat preoccupied to observe atmospheric phenomena such as tornadoes... I am yet to hear of any anecdotal evidence of sudden directional wind change suggestive of a tornado during any cyclonic event.

Storm surge is a bit of a wild card for design (and a gaping loop hole for insurers). Having observed first hand results of somewhat 'minor' storm surge i cannot envision a practical means of codifying or implementing a change.

 

[jhardy1]

I'm not sure about the likelihood of a tornado striking DURING an actual cyclone event (I'm not sure how you could even tell if a tornado hit you, while you are in the middle of a Cat 5 cyclone!), but there are certainly reports of tornadoes being possible within current active cyclone-alert areas. E.g. a "mini-tornado" hit Karratha in February 2011, while the town was hunkering down for Cyclone Carlos; see following news report with video:

http://www.australiangeographic.com.au/journal/wa-town-hit-by-cyclone-related-tornado.htm

 

[csd72]

OzEng80,

They design for storm surge on coastal buildings in the US where there is the possibility of hurricanes and this is codified in the building code. The requirements are basically for the bottom floor to have a certain percentage open or for brakaway walls that will break in the event of a surge. This can be avoided if it is over a certain level above sea level or has been designed to resist the applied forces.

Not that difficult to do.

Probably should also have similar provisions for buildings in flood planes.