Systematic Experimental Approach to Determine Banging Noise Source and Location of a Steel Box Girder Using Vibroacoustic Analysis

Unexpected banging noises occurring on the Beomseo Bridge in Ulsan, South Korea have been reported during and after the steel box-girder erection. The banging noise, which at maximum reached 120 dB, raised concerns among drivers and nearby residents about the safety of the bridge. This paper aims to experimentally investigate the source locations and causes of these randomly occurring noises and propose methods for noise control. A vibroacoustic monitoring program was conducted using measuring devices such as sound level meters, acoustic cameras, and accelerometers. The data were analyzed to determine noise source localizations, causes of banging noises, and mechanism of noise generation. Based on the finding that changes in the temperature of the girders led to increases in the number of noise occurrences, bridge investigation results showed that stick-slip motion in the spherical bearing resulted in these abnormal noise events. To reduce the banging noises, two possible methodologies for noise control were proposed: (1) noise source modification, and (2) control of the transmission path.