Construction Time Wind Load 3

[IJR]

What is the minimum wind load used to check erection time conditions?

Or where is this issue well covered?

Assume you have to erect a long span truss on temporary structure on an open terrain at elevation above 10meters(33ft). Workers will be working on the temporary structure for at least two weeks.

 

[UcfSE]

You can check out ASCE's "Design Loads on Structures During Construction, SEI/ASCE 37-02". That might help.

https://www.asce.org/bookstore/book.cfm?book=4242

 

[JAE]

Try this document:

Design Loads on Structures During Construction, SEI/ASCE 37-02
(ASCE Standard No. 37-02)

found at:

https://www.asce.org/bookstore/book.cfm?book=4242

 

[SlideRuleEra]

An alternate approach, that may apply to your situation, is to check out the "California Falsework Manual" (free .pdf download at this link)

http://www.dot.ca.gov/hq/esc/construction/Manuals/Falsework/Falsework.htm

Chapter 3 covers "Design Consideration". Starting on page 3-4 there is a discussion of allowable horizontal construction loads (from any source, wind included). This manual limits allowable horizontal forces to 2% of total dead load. Ways to back-figure the allowable wind speed are discussed.

It is interesting that the manual (accurately, in my opinion) points out that there is no need for precise assumpitions and calculations since the whole situation is complex and changing as work progresses.

http://www.SlideRuleEra.net

 

[JAE]

UcfSE - you're just a second faster on the draw....way to go.

 

[JAE]

...great minds think alike.

 

[UcfSE]

That's what I was thinking when I saw that Thanks JAE

 

[IJR]

I am going to purchase that AISC spec, but if you find time you might what to brief me on the level of wind mentioned in the spec

European draft code hints a wind speed of return period of 2 years to be used in all erection jobs.

But as you might know such a general statement can be very annoying because wind speeds as used in ASCE I guess are 50 year winds and they are MEAN values measured at 33ft (10m) height on a clear terrain with NO GUST taken into account.You take into accout gusts etc with a separate factor. You convert that to 10 year wind by some rules of thumb like factor 0.75. No joke I will never guess what 2 year no gust mean wind speed will mean what!

Winds cited in Russian codes can be seemingly very low, while in fact they are based on a different set of measurements which I have never found to time to fully study given the language barrier.

(Some codes tend to mention gust speeds as basis of wind data).

Thanks & regs

IJR

 

[UcfSE]

You convert wind speeds based on return period with a table in the ASCE 7 that gives you factors by which to multiply the 50-year wind speed for the given return period you want.