POD-based representation of the alongwind Equivalent Static Force for long-span bridges

This paper develops and discusses a method by which it is possible to evaluate the Equivalent Static Force (ESF) of wind in the case of long-span bridges. Attention is focused on the alongwind direction. The study herein carried out deals with the classical problems of determining the maximum effects due to the alongwind action and the corresponding ESFs. The mean value of the maximum alongwind displacement of the deck is firstly obtained both by the spectral analysis and the Gust Response Factor (GRF) technique. Successively, in order to derive the other wind-induced effects acting on the deck, the Gust Effect Factor (GEF) technique is extended to long-span bridges. By adopting the GRF technique, it is possible to define the ESF that applied on the structure produces the maximum alongwind displacement. Nevertheless the application of the ESF so obtained does not furnish the correct maximum values of other wind-induced effects acting on the deck such as bending moments or shears. Based on this observation, a new technique is proposed which allows to define an ESF able to simultaneously reproduce the maximum alongwind effects of the bridge deck. The proposed technique is based on the GEF and the POD techniques and represents a valid instrument of research for the understanding of the wind excitation mechanism.

[1]  G. Solari,et al.  Probabilistic 3-D turbulence modeling for gust buffeting of structures , 2001 .

[2]  Giovanni Solari,et al.  Wind modes for structural dynamics: a continuous approach , 2002 .

[3]  Alan G. Davenport,et al.  Gust Loading Factors , 1967 .

[4]  Yukio Tamura,et al.  Universal wind load distribution simultaneously reproducing largest load effects in all subject members on large-span cantilevered roof , 2007 .

[5]  Guy L. Larose,et al.  Performance of streamlined bridge decks in relation to the aerodynamics of a flat plate , 1997 .

[6]  Alessandra Fiore,et al.  A method to evaluate the frequencies of free transversal vibrations in self-anchored cable-stayed bridges , 2005 .

[7]  L. Carassale,et al.  Modal transformation tools in structural dynamics and wind engineering , 2000 .

[8]  Giovanni Solari,et al.  Gust buffeting of long span bridges: Double Modal Transformation and effective turbulence , 2007 .

[9]  Giovanni Solari,et al.  DOUBLE MODAL TRANSFORMATION AND WIND ENGINEERING APPLICATIONS , 2001 .

[10]  Giovanni Solari,et al.  Proper orthogonal decomposition in wind engineering. Part 2: Theoretical aspects and some applications , 2007 .

[11]  Giovanni Solari.  Alongwind Response Estimation: Closed Form Solution , 1982 .

[12]  A G Davenport,et al.  NOTE ON THE DISTRIBUTION OF THE LARGEST VALUE OF A RANDOM FUNCTION WITH APPLICATION TO GUST LOADING. , 1964 .

[13]  Luigi Carassale,et al.  POD-based filters for the representation of random loads on structures , 2005 .

[14]  D. B. Preston.  Spectral Analysis and Time Series , 1983 .

[15]  Giovanni Solari,et al.  Equivalent static wind actions on vertical structures , 2004 .

[16]  Giovanni Solari,et al.  3-D gust effect factor for slender vertical structures , 2002 .

[17]  M. Di Paola,et al.  Digital generation of multivariate wind field processes , 2001 .