03-31-2013, 04:33 PM
Fatigue life estimation of steel girder of Yangpu cable-stayed Bridge due to buffeting
Author: M. Gu, Y.L. Xu, L.Z. Chen, H.F. Xiang | Size: 349 KB | Format: PDF | Quality: Unspecified | Publisher: Elsevier | Year: 199 | pages: 18
As the main span of modern cable-stayed bridges becomes longer and longer, the bu¤etinginduced
fatigue damage problem of steel girders located in strong wind regions may have to be
taken into consideration in the design of the bridge. This paper presents a method in the mixed
frequencyÐtime domain for estimating the fatigue life of steel girders of the Yangpu cable-stayed
Bridge due to bu¤eting. In the suggested method, the joint probability density function of wind
speed and wind direction at the deck level of the bridge is Þrst established. The power spectra of
the critical stress of the girder are then derived from the power spectra of the generalized
coordinates of the bridge for di¤erent wind speeds and wind directions. The derived stress
spectra are no longer a narrow spectrum when the background component of stress response is
included. Thus, the time histories of the critical stress are simulated from their power spectra
and the stress cycle distributions are estimated in terms of rainßow count method. The formulae
derived based on the modiÞed Miner law and the random vibration theory are Þnally used for
estimating the fatigue life of the bridge girder. The results show that the e¤ects of wind direction
on the fatigue life of the Yangpu Bridge are signiÞcant. The predicted fatigue life due to
bu¤eting is much longer than the design life of the bridge
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