This paper attempts a state-of-the-art summary of research into thunderstorm wind fields from an engineering perspective. The characteristics of thunderstorms and the two extreme wind events-tornadoes and downbursts-spawn by thunderstorms are described. The significant differences from traditional boundary layer flows are highlighted. The importance of thunderstorm gusts in the worldwide database of extreme wind events is established. Physical simulations of tornadoes and downbursts are described and discussed leading to the recommendation that Wind Engineering needs to focus more resources on the fundamental issue - What is the flow structure in the strongest winds? © 2002 Published by Elsevier Science Ltd.

Thunderstorms - their importance in Wind Engineering (A case for the next generation wind tunnel)

In 1961, Davenport published a paper, considered by most a constitutive deed of wind engineering, in which meteorology, micrometeorology, climatology, aerodynamics and structural dynamics were embedded in a homogeneous framework of the wind loading of structures. This framework, known as Davenport chain and based on a wind model coherent with synoptic-scale extra-tropical cyclones, is so limpid and elegant as to become, in the course of the years, a sort of axiom. Between 1976 and 1978 Gomes and Vickery separated thunderstorm from non-thunderstorm winds, determined their extreme wind speed marginal distributions and from them derived a mixed statistical model later extended to other wind phenomena. This viewpoint, dealt with as a milestone in the emerging issue of mixed climatology, proved the impossibility to label a heterogeneous range of phenomena endowed with different velocity fields, frequencies, durations and sizes by the generic term “wind”. Many wind types, in particular tropical cyclones, tornadoes and downslope winds, occur in limited and well-known areas. Extra-tropical cyclones and thunderstorms are natural hazards that affect the whole planet. This paper provides a state-of-the-art about thunderstorm downburst, one of the most spectacular and damaging events produced by nature, and its wind loading of structures. Also in the light of planet's climatology evolution, this topic is a key issue of structural safety and sustainability.

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Thunderstorm Downbursts and Wind Loading of Structures: Progress and Prospect

Modern wind engineering was born in 1961, when Davenport published a paper in which meteorology, micrometeorology, climatology, bluff-body aerodynamics and structural dynamics were embedded within a homogeneous framework of the wind loading of structures called today “Davenport chain”. Idealizing the wind with a synoptic extra-tropical cyclone, this model was so simple and elegant as to become a sort of axiom. Between 1976 and 1977 Gomes and Vickery separated thunderstorm from non-thunderstorm winds, determined their disjoint extreme distributions and derived a mixed model later extended to other Aeolian phenomena; this study, which represents a milestone in mixed climatology, proved the impossibility of labelling a heterogeneous range of events by the generic term “wind”. This paper provides an overview of this matter, with particular regard to the studies conducted at the University of Genova on thunderstorm downbursts.

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Mixed Climatology, Non-synoptic Phenomena and Downburst Wind Loading of Structures

A closed-form solution for the wind-induced responses of transmission lines considering the failure of adjacent towers

A numerical simulation procedure for predicting the response of a single span transmission line to strong turbulent winds is described. The wind velocities are generated using a 'Monte Carlo' technique based on an Inverse Fast Fourier Transform; the equations of motion of the line are then solved numerically using a finite difference method. Results obtained using the method were compared with those from linearised random vibration theory. Effects due to the mean swing angle of the line, and due to the excitation of an in-plane mode of vibration were apparent.

Simulation of the Dynamic Response of Transmission Lines to Strong Winds

Analysis of buffeting response of hinged overhead transmission conductor to nonstationary winds

Monitoring of horizontal displacement is essential for structural health monitoring of high-rise structures. This paper proposes a new technique for estimating the horizontal displacement using fusion measurements including strain and acceleration for high-rise structures. The quasi-static component of structural displacement is first derived from the measured longitudinal strains based on the classical beam theory . The quasi-static displacement is then combined with the resonant displacement determined based on the measured acceleration via a finite impulse response filtering approach to obtain the total horizontal displacement. The effectiveness of the proposed technique is examined through numerical studies, in which two cantilever beams with different sectional shapes are used to verify that the proposed technique can provide accurate estimation of horizontal displacements under different noise levels contained in signals and number of measurement points. Then, a field measurement validation study on a 600 m high skyscraper is presented to demonstrate the applicability and accuracy of the proposed technique for horizontal displacement estimation of high-rise buildings under typhoon conditions. • Propose a horizontal displacement estimation technique fusing acceleration and strain measurements for high-rise structures. • Examine the effectiveness and accuracy of the proposed technique through numerical validation studies. • Verify the performance of the proposed technique based structural responses of a skyscraper under typhoon condition. 

Kang Xu

Papers

Analysis of buffeting response of hinged overhead transmission conductor to nonstationary winds

Horizontal displacement estimation of high-rise structures by fusing strain and acceleration measurements

Investigation of modal parameters of a 600-m-tall skyscraper based on two-year-long structural health monitoring data and five typhoons measurements

Adaptive fuzzy variable fractional-order sliding mode vibration control of uncertain building structures

An improved stochastic subspace modal identification method considering uncertainty quantification