SOME RECENT PROGRESSES IN BRIDGE WIND ENGINEERING RESEARCH

Some recent progresses are reported according to the actual need of bridge design against wind loading. (1) A forced vibration testing method of sectional models in wind tunnel and its time-domain analysis and frequency-domain analysis for identifying the flutter derivatives associated with the experimental method were developed. A comparative study between the two analyzing methods was conducted on the same experimental data. Frequency-domain method had a large capacity against noises, resulting in smooth curves of flutter derivatives with a filtration process included; the formulation of time-domain method was relatively sensitive to signal phase difference and it was apt to be disturbed by noises such that the results might shift or fluctuate. (2) The aerodynamic interference between two separate girders and between two parallel main cables of double deck bridges were studied, taking Fushan Pingsheng bridge as an example. (3) On-site observation of wind-rain induced vibration of stay cables and its control with MR dampers were conducted. A monitoring system for wind-rain induced vibration was built on the Dongting Lake Bridge and has been in service for four years. Some new discoveries were obtained in the influence of wind speed, wind direction and rainfall on wind-rain induced vibration and in the vibration shape of stay cables. A new technique of mitigating cable vibration using magneto-rheological (MR) dampers was exploited and applied on the Dongting Lake Bridge in 2002. The observations of the past three years show that the effectiveness of the vibration is well. (4) To avoid the purposive destruction of the power supply system to MR dampers, a permanent magnet-adjusting and assembled magneto-rheological (PMAA-MR) damper was developed and successfully fitted on the Hongshan Bridge in Changsha.