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Topographic Multiplier (Mt) - AS1170.2

Topographic Multiplier (Mt) - AS1170.2

Topographic Multiplier (Mt) - AS1170.2

(OP)
Guys, long time reader, first time poster.

I have a site address in New Zealand and I'm really struggling to figure out what the Mt value should be.

In the PDF labelled Mt help 1, it is very easy. However in the PDF labelled PDF help 2, I'm unsure as to what should be the ridge or the valleys, or are we half way up the hill.

Does anyone have any good guidance on how to treat this situation.


RE: Topographic Multiplier (Mt) - AS1170.2

Steve,
Yes the Mt factor in ASA1170.2 or any code is hard to get right.

From my experience, you need to figure out the ridge and valleys up the slope. Referring to your elevation Mt help 2, there would be many ridges and valleys in my opinion (3 to be exact), you should consider them all. Yes it is time consuming, but when it is not obvious which one will govern you need to break them down and assess each one.

For the past while we have referenced the mapping done by branz, however how this relates to an MT value still took a lot of time. http://www.branz.co.nz/cms_display.php

However this week a program we use regularly got updated to calculate Mt automatically, does a good job recognizing the top and bottom of hills from what I can see.

I have tried to get the same location as yours outside snowdon (got this from your screen shot on help 2), I think I was successful as my southern elevation profile looks the same as yours. Any way I have dropped the screen shot of the location in a pdf for your info with all the MT values.













http://www.nceng.com.au/
"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

RE: Topographic Multiplier (Mt) - AS1170.2

(OP)
Thanks rowing engineer.

I don't think you are close with the elevations, any chance could you tell us what program this is your using? and I can do it myself.

RE: Topographic Multiplier (Mt) - AS1170.2

Steve,
It isn't really encouraged to promote software on this website but the software is:

Website: https://www.revolutio.com.au/software/checkpole/

http://www.nceng.com.au/
"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

RE: Topographic Multiplier (Mt) - AS1170.2

Sounds a lot like the Kzt factor in ASCE 7...

Mike McCann, PE, SE (WA)


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