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RISS 인기검색어
- 검색키워드
- 저자 : Hua W. Niu (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Hua, X.G.,Chen, Z.Q.,Chen, W.,Niu, H.W.,Huang, Z.W. Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.2
Higher-mode vertical vortex-induced vibrations (VIV) have been observed on several steel box-girder suspension bridges where different vertical modes are selectively excited in turn with wind velocity in accordance with the Strouhal law. Understanding the relationship of VIV amplitudes for different modes of vibration is very important for wind-resistant design of long-span box-girder suspension bridges. In this study, the basic rectangular cross-section with side ratio of B/D=6 is used to investigate the effect of different modes on VIV amplitudes by section model tests. The section model is flexibly mounted in wind tunnel with a variety of spring constants for simulating different modes of vibration and the non-dimensional vertical amplitudes are determined as a function of reduced velocity U/fD. Two 'lock-in' ranges are observed at the same onset reduced velocities of approximately 4.8 and 9.4 for all cases. The second 'lock-in' range, which is induced by the conventional vortex shedding, consistently gives larger responses than the first one and the Sc-normalized maximum non-dimensional responses are almost the same for different spring constants. The first 'lock-in' range where the vibration frequency is approximately two times the vortex shedding frequency is probably a result of super-harmonic resonance or the "frequency demultiplication". The main conclusion drawn from the section model study, central to the higher-mode VIV of suspension bridges, is that the VIV amplitude for different modes is the same provided that the Sc number for these modes is identical.
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X.G. Hua,Z.Q. Chen,W. Chen,H.W. Niu,Z.W. Huang 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.20 No.2
Higher-mode vertical vortex-induced vibrations (VIV) have been observed on several steelbox-girder suspension bridges where different vertical modes are selectively excited in turn with windvelocity in accordance with the Strouhal law. Understanding the relationship of VIV amplitudes for differentmodes of vibration is very important for wind-resistant design of long-span box-girder suspension bridges. In this study, the basic rectangular cross-section with side ratio of B/D=6 is used to investigate the effect ofdifferent modes on VIV amplitudes by section model tests. The section model is flexibly mounted in windtunnel with a variety of spring constants for simulating different modes of vibration and the non-dimensionalvertical amplitudes are determined as a function of reduced velocity U/fD. Two ‘lock-in’ ranges are observedat the same onset reduced velocities of approximately 4.8 and 9.4 for all cases. The second ‘lock-in’ range,which is induced by the conventional vortex shedding, consistently gives larger responses than the first oneand the Sc-normalized maximum non-dimensional responses are almost the same for different springconstants. The first ‘lock-in’ range where the vibration frequency is approximately two times the vortexshedding frequency is probably a result of super-harmonic resonance or the “frequency demultiplication”. The main conclusion drawn from the section model study, central to the higher-mode VIV of suspensionbridges, is that the VIV amplitude for different modes is the same provided that the Sc number for thesemodes is identical.
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Monitoring and control of wind-induced vibrations of hanger ropes of a suspension bridge
Xu G. Hua,Zheng Q. Chen,Xu Lei,Qin Wen,Hua W. Niu 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.6
In August 2012, during the passage of the typhoon Haikui (1211), large amplitude vibrations were observed on long hangers of the Xihoumen suspension Bridge, which destroyed a few viscoelastic dampers originally installed to connect a pair of hanger ropes transversely. The purpose of this study is to identify the cause of vibration and to develop countermeasures against vibration. Field measurements have been conducted in order to correlate the wind and vibration characteristics of hangers. Furthermore, a replica aeroelastic model of prototype hangers consisting of four parallel ropes was used to study the aeroelastic behavior of hanger ropes and to examine the effect of the rigid spacers on vibration mitigation. It is shown that the downstream hanger rope experiences the most violent elliptical vibration for certain wind direction, and the vibration is mainly attributed to wake interference of parallel hanger ropes. Based on wind tunnel tests and field validation, it is confirmed that four rigid spacers placed vertically at equal intervals are sufficient to suppress the wake-induced vibrations. Since the deployment of spacers on hangers, server hanger vibrations and clash of hanger ropes are never observed.
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