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MiScion Pty Ltd
Structural Design
Structural Design

MiScion Pty Ltd's posts

Got side tracked from what I wanted. Was going to put business on map, then got confusing with google my business. Got part way through setup and decided to delete as seemed to be creating a duplicate google+ page.

Seem to recollect some earlier research when created the page that local business registration was bad idea: but they changed name as they do.

Also android app didn't seem to have a logout option. And it was an update of some earlier app which became disabled on update. So uninstalled it.

Bad day: but then it is 1:00am.

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The advantage of industrial product design.

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chart of wind speed comparison

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Compare beaufort windscale against AS4055, and convert wind speeds from m/s to km/h.

Adelaide storms. 125km/h. Compare with region A, basic regional wind speed of 162km/h (500 year mean return period) for normal buildings, and 172km/h (2000 year mean return period) for post disaster. These are ultimate strength design wind speeds. (AS1170.2)

Further compare that with the concept that some infrastructure was designed for minimum design wind speed of 30m/s [108 km/h], for serviceability, no consideration of ultimate strength. That is if antenna tower deflects too much then loose signal. If power cables and towers deflect too much then cables may touch, or may have some other problem.

But the issue of ultimate strength: the limit state at which materials permanently deform and no elastic recovery occurs when load removed: and the structure will need replacing not really considered.

So cannot say at what wind speed the power pylons should collapse, because in the main not a design consideration in the first place. (though could work the calculations backwards from resistance.)

Though I recollect newer codes for poles and lattice towers do now refer to AS1170.2 rather than being self contained. So newer towers should fair better than older towers.

As for losing house roof when lose verandah, that doesn't surprise me. As keeping house roof would require a verandah builder that takes wind loading seriously. Simply adding extra straps to tie the house rafter to the house wall top plate is not good enough. The top plate can be pulled off.

Wind class N1 on Adelaide map is mostly nonsense. A site check is likely to find do not have shielding in all directions, and that puts into lower range of wind class N2. Most wind class N3 sites when checked are in upper range of wind class N2. Basically every where in metro area is N2. The wind classes are not sensibly divided. The classes should be separated by smaller increments for low wind speeds and then by larger increments at higher wind speeds: something along the lines of Renard numbers. More over the wind classification system should include the minimum speed of 30 m/s.

But minimum is 28m/s? No it isn't, since buildings are never and have never been designed for that wind speed. It is a meaningless number. The ultimate strength design wind speed for N1 is 34m/s [122km/h] at this speed the building is damaged and in need of replacing or major repair.


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Setup instructions for spreadsheet environment for using my structural design workbooks.
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