Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Wind Speeds for the Estimation of World Trade Center Towers' Response



William P. Fritz, Fahim H. Sadek, Emil Simiu


Estimates of the World Trade Center (WTC) towers response to wind by two North American wind engineering laboratories differed from each other by almost 40 %. A recent investigation by the National Institute of Standards and Technology determined that those differences were mainly due to discrepancies between the respective estimates of the wind speeds. In this paper we present a procedure for estimating extreme wind speeds near the WTC site that corresponds to a sector-by-sector approach to the estimation of extreme wind effects. We provide details of the data sets and their treatment, as well as details of the estimates themselves, in a manner intended to be thorough, clear, and transparent. Efforts in the direction of clarity and transparency are in our view necessary if estimates of extreme winds and their effects are to meet the need for effective scrutiny by users and building authorities, and if a solid technical basis for a consensus that remains to be developed among standard and professional organizations is to be created in the near future. Our analyses indicate that sectorial extreme wind speeds, and their counterparts in methods based on the up-crossing technique, are sensitive to sampling errors of a type that does not affect estimates of extreme wind speeds considered without regard for their direction. For this reason, estimates based on overly refined schemes for taking wind directionality into account and that disregard the possibility of such sampling errors are in our opinion prone to being significantly in error.
Proceedings Title
Conference Dates
May 1, 2006
Conference Location
Conference Title
ASCE Structures Congress


Fritz, W. , Sadek, F. and Simiu, E. (2017), Wind Speeds for the Estimation of World Trade Center Towers' Response, 2006, Undefined (Accessed May 22, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created February 19, 2017