Unbalanced wind buffeting effects on bridges during double cantilever erection stages

Abstract

This paper is focused on the torsional effects that are induced on bridge piers by unbalanced windrnbuffeting on the deck during double cantilever erection stages. The case of decks with variable cross section isrnconsidered in particular as this characteristic is typical of most frame bridges that are built by the cantileverrnmethod. The procedure outlined in the paper is basically an application of the method that Dyrbye and Hansenrn(1996) have illustrated for decks with constant cross section. This format was chosen because it is suitable forrndesign purposes and may easily be implemented in structural codes. As a complement, the correspondence withrnthe format that is adopted in the Canadian code (NBCC 1990) for the gust factor is established, which might bernuseful to bridge designers used to the North-American approach to the gust effects on structures. Onlyrnalongwind turbulence and horizontal movements of the deck are considered. The combination of torsional andrnbending effects is also discussed and it is illustrated with an example of application.