Title page for ETD etd-32198-124554


Type of Document Dissertation
Author Janajreh, Isam Mustafa II
Author's Email Address janajreh@vt.edu
URN etd-32198-124554
Title Wavelet Analysis of Extreme Wind Loads on Low-Rise Structures
Degree PhD
Department Engineering Mechanics
Advisory Committee
Advisor Name Title
Hajj, Muhammad R. Committee Chair
Heller, Robert E. Committee Member
Kohler, Werner E. Committee Member
Mook, Dean T. Committee Member
Ragab, Saad A. Committee Member
Tieleman, Henry W. Committee Member
Keywords
  • pressure coefficients
  • turbulence intensities
  • turbulence scales
  • wavelets
  • wind loads
  • higher-order statistics
  • intermittency
Date of Defense 1998-01-29
Availability unrestricted
Abstract
Over the past thirty years, extensive research has been conducted with the objective of reducing wind damage to structures. Wind tunnel simulations of wind loads have been the major source of building codes. However, a simple comparison of pressure coefficients measured in wind tunnel simulations with full-scale measurements show that the simulations, in general, underpredict extreme negative pressure coefficients. One obvious reason is the lack of consensus on wind tunnel simulation parameters.


The wind in the atmospheric surface layer is highly turbulent. In simulating wind loads on structures, one needs to simulate the turbulent character besides satisfying geometric and dynamic similitudes. Some turbulence parameters that have been considered in many simulations include, turbulence intensities, integral length scales, surface roughness, and frequency spectrum. One problem with these parameters is that they are time varying in the atmospheric boundary layer and their averaged value, usually considered in the wind tunnel simulations, cannot be used to simulate pressure peaks.


In this work, we show how wavelet analysis and time-scale representation can be used to establish an intermittency factor that characterizes energetic turbulence events in the atmospheric flows. Moreover, we relate these events to the occurrence of extreme negative peak pressures.

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