Evaluation of typhoon induced fatigue damage for Tsing Ma Bridge

This paper aims to evaluate the effect of a typhoon on fatigue damage in steel decks of long-span bridges. The strain-time histories at critical locations of deck sections of long-span bridges during a typhoon passing the bridge area are investigated by using on-line strain data acquired from the structural health monitoring system permanently installed on the bridge. The fatigue damage models based on Miner’s law and the continuum damage mechanics are applied to calculate increment of fatigue damage due to the action of a typhoon. The analytical results for the Tsing Ma Bridge show that the stress spectrum generated by a typhoon is much different than that by the normal traffic and its histogram shapes can be described approximately as a Rayleigh distribution. The influence of typhoon loading on accumulative fatigue damage is more significant than that due to normal traffic loading. The increment of fatigue damage generated by hourly stress spectrum for the maximum typhoon loading may be much greater than that by daily stress spectrum for normal traffic loading. The results suggest that it is necessary to evaluate typhoon induced fatigue damage for the purpose of accurately evaluating accumulative fatigue damage for the long-span bridge located at the typhoon prone region.