×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Calculate Ultimate Load Using Wind Speed ASCE 7-05

Calculate Ultimate Load Using Wind Speed ASCE 7-05

Calculate Ultimate Load Using Wind Speed ASCE 7-05

(OP)
I am looking for information about using a wind speed increase (above the design wind speed) to compute the ultimate load value for a structures MWFRS.  I have read some older post suggesting a value of 1.3 for increasing the design load wind speed to compute the ultimate load wind speed (DS*1.3).  I have also seen DS*1.3^.5.  Where DS is the design wind speed based upon the wind speed map in ASCE 7-05.

The ultimate load wind speed was then used in the calculation of the MWFRS to compute the ultimate load of the structure.

I am hoping to find a referred journal article on this topic, and how ultimate load changes over time (if it does), and what factors cause the change and a method for calculating the change (I know, I am asking a lot!).

Any help would be most appreciated.

Thank you,

The Inspector General

RE: Calculate Ultimate Load Using Wind Speed ASCE 7-05

Unless things have changed since I retired, the design wind speed is the design wind speed. The basic wind pressure is then multiplied by a number of other factors. Then, the result is subject to the load factors in various load combinations.

Michael.
Timing has a lot to do with the outcome of a rain dance.

RE: Calculate Ultimate Load Using Wind Speed ASCE 7-05

ASCE 7-10 is based on ultimate wind speeds.  The main journal article source for this revision is as follows:

Ultimate Wind Load Design Gust Wind Speeds
in the United States for Use in ASCE-7-10
Peter J. Vickery1; Dhiraj Wadhera; Jon Galsworthy; Jon A. Peterka; Peter A. Irwin; and
Lawrence A. Griffis:  ASCE Journal of Structural Engineering, May 2010.  

Basing this on ASCE 7-05 though, the load factor is 1.6 on wind pressure (the load factor takes the design wind pressure 1.0W up to ultimate values at 1.6W).  So if for some reason you need to know the conversion based on wind speed, you would use sqrt(1.6) = 1.27 based on force being derived from velocity squared.   

This conversion is apparent in the new ASCE 7-10 maps which provide the ultimate wind speed for the majority of the country as 114 mph (=90mph x 1.27).      

 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources