Monday, November 21, 2011

RE: Design Values for Brazil

“Wind Loading of Structures” second edition by John D. Holmes, page 347, Appendix D, Section D2.9 says


“In Brazil, extreme winds are produced primarily by a mixture of large extra-tropical depression systems and local thunderstorm downdrafts (Riera and Nanni, 1989). The coastline of the South Atlantic normally does not experience tropical cyclones due to the low water temperature; however a cyclonic system (named ‘Catarina’) with the characteristics of a weak hurricane, formed off the coastline of southern Brazil in January 2004 (Loredo-Souza and Paluch, 2005).


Salagado Vieira Filho (1975) carried out extreme value analyses of wind speeds for 49 Brazilian stations, but used the conservative Frechet Distrubution for predictions, and apparently the data were not separated by storm type. Later analyses by Riera and Nanni (1989) indicate that thunderstorm winds are dominant in most locations. Jeary (1997b) lists 10 years of recorded wind speeds (from 3m height) for three stations in Rio de Janeiro. The Brazilian wind loading code (NBR-6123, 1987) gives isotachs of 3-s gust speeds with 50-year return period varying from 30 m/s (north half of the country) to 50 m/s (extreme south). Extreme wind classifications: I (north of 20°): II (south central); III (extreme south).”


The last sentence refers to a classification system indicated by Table D1 on page 345 in the referenced book.


Table D1 A classification system for design wind speeds (50 –year return period wind speeds at 10 m height)


Level                     3-s gust (m/s)                    10-min mean (m/s)

I                               <35                                         <22

II                             35-45                                     22-30

III                            45-55                                     30-35

IV                            55-65                                     35-40

V                             >65                                         >40        “


I hope you find this helpful, I highly recommend this book published by Taylor and Francis.


Joseph M. Bowman, P.E.




From: Rich Kipke []
Sent: Saturday, November 19, 2011 12:09 PM
Subject: Design Values for Brazil

). E

I'm trying to find  Wind Criteria for Santa Maria, Brazil - located at the far south of Brazil, about 100 miles inland.  I've found pretty good seismic data in the Corp of Engineer documents, but no Wind.  Any help?


(prefer an ASCE equivalent if it's available)




Rich Kipke