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Abstract

Conventional sensors, such as the accelerometers and velocimeters, have been generally adopted to conduct the vibration measurements of stay cables for the identification of their dynamic parameters. Even though these contact sensors are able to obtain accurate measurements, the installation of such devices may require substantial efforts. A simple digital videogrammetric technique without using any artificial target is developed in this study to perform the ambient vibration measurements of stay cables for the subsequent identification of cable frequencies. This method significantly simplifies the image processing procedures by exploiting the straight boundary of cable to determine the midpoint of its edge line for serving as a convenient pseudo target. Demonstrated by the on-site measurements for three different cables selected from Chi-Lu Bridge, it is shown that this nontarget technique equipped with a customer grade camcorder and an ordinary tripod placed on the bridge deck can attain the same order of accuracy for cable frequency identification as that of high-resolution velocimeters. Both the vertical and transverse displacements of cable were measured under the ambient vibration amplitudes in the order of 0.5 mm and 0.2 mm, respectively. Based on this study, it is proved that the practical application of a nontarget videogrammetric technique to the cables of long-span cable-stayed bridges is not only feasible but also advantageous in many aspects.

Keywords

stay cable ambient vibration measurement modal frequency nontarget technique customer grade camcorder tripod

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References

Chen

C.C.

W.H.

and Liau

J.A.

(2008a). “Modal frequency identification for cable and girder using ambient vibration signals”, Journal of Chinese Institute of Civil and Hydraulic Engineering, Vol. 20, No. 4, pp. 415–427.

Chen

C.C.

W.H.

and Tseng

H.Z.

(2008b). “Measurement of ambient vibration signal of shorter stay cables from stressing to service stages”. Proceedings of 4^th European Workshop on Structural Health Monitoring, Krakow, Poland, July.

Chen

C.C.

W.H.

Tseng

H.Z.

Lai

G.L.

and Shieh

I.D.

(2010). “Application of digital photometry techniques in identifying the modal frequencies of stay cables”, Journal of Chinese Institute of Civil and Hydraulic Engineering, Vol. 22, No. 4, pp. 411–421.

Hartley

and Zisserman

(2003). Multiple View Geometry in Computer Vision, Cambridge University Press, Cambridge, UK.

Y.F.

and Chang

C.C.

(2008). “Nontarget image-based technique for small cable vibration measurement”, Journal of Bridge Engineering, ASCE, Vol. 13, No. 1, pp. 34–42.

Jiang

Jauregui

D.V.

and White

K.R.

(2008). “Close-range photogrammetry applications in bridge measurement: Literature review”, Measurement, Vol. 41, No. 8, pp. 823–834.

Karara

H.M.

(1989). Non-Topographic Photogrammetry, American Society for Photogrammetry and Remote Sensing, Bethesda, Maryland, USA.

Lee

J.J.

and Shinozuka

(2006). “Real-time displacement measurement of a flexible bridge using digital image processing techniques”, Proceedings of the Society for Experimental Mechanics, Vol. 46, No. 1, pp. 105–114.

Olaszek

(1999). “Investigation of the dynamic characteristic of bridge structures using a computer vision method”, Measurement, Vol. 25, No. 3, pp. 227–236.

10.

Patsias

and Staszewski

W.J.

(2002). “Damage detection using optical measurement and wavelet”, Structural Health Monitoring, Vol. 1, No. 1, pp. 7–22.

11.

Phelan

R.S.

Sarkar

P.P.

and Mehta

K.C.

(2006). “Full-scale measurements to investigate rain-wind induced cable-stay vibration and its mitigation”, Journal of Bridge Engineering, ASCE, Vol. 11, No. 3, pp. 293–304.

12.

Rafael

C.G.

and Richard

E.W.

(1992). Digital Image Processing, Addison-Wesley, San Diego, USA.

13.

Shih

M.H.

Tong

S.H.

Song

W.P.

and Kuo

R.C.

(2008). “Monitoring of the static and dynamic displacements of bridges using digital image correlation technique”, Journal of Chinese Institute of Civil and Hydraulic Engineering, Vol. 35, No. 5, pp. 64–71.

14.

Virlogeux

(1998). “Cable vibrations in cable-stayed bridges”. Proceedings of International Symposium on Advances in Bridge Aerodynamic, Copenhagen, Denmark, May, pp. 213–233.

15.

Wang

M.L.

(2005). “Health monitoring and assessment of long-span bridges”. Proceedings of 2^nd International Conference on Structural Health Monitoring of Intelligent Infrastructure, Shenzhen, China, November, pp. 121–132.

16.

Zui

Shinke

and Namita

(1996). “Practical formulas for estimation of cable tension by vibration method”, Journal of Structural Engineering, ASCE, Vol. 122, No. 6, pp. 651–656.

Modal Frequency Identification of Stay Cables with Ambient Vibration Measurements Based on Nontarget Image Processing Techniques

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