Forced and Ambient Vibration Tests and Vibration Monitoring of Hakucho Suspension Bridge

Abstract

Forced and ambient dynamic tests of the Hakucho Bridge were carried out to study the dynamic characteristics of this suspension bridge. Dense-array measurement was employed in order to capture not only natural frequencies and damping, but also the mode shapes of the bridge. The natural frequencies and mode shapes obtained from the forced and ambient vibration tests agreed well with those calculated by a three-dimensional finite element model. A new method that combines the random decrement method with the Ibrahim time domain method is proposed to systematically identify the natural frequencies, damping, and mode shapes. This method is successfully applied to ambient vibration data. It is shown that the natural frequency of the first vertical bending mode decreases noticeably as the wind speed increases. It is also shown that the shape of the first vertical bending mode changes slightly near the towers, depending on the wind velocity; this finding indicates that the change may be associated with friction in the bearings at the towers. Finally, application of the Global Positioning System to measure static displacement of the girder is explained.

System identification of the Vincent Thomas suspension bridge using earthquake records

“…Note that because there are n 1 identical R's, the i 's can then be solved directly from R i = b i ; i= 1; : : : ; n 1 (6) That is, each row of the j A matrices is identiÿed independently. Note that in general j A will be unsymmetric even when M 11 , C 11 and K 11 are symmetric.…”

“…While there has been a considerable amount of system identiÿcation studies concerned with building-like structures under ambient, earthquake and wind excitations, as well as studies of small highway overpass bridges under such excitations, relatively few studies are available concerning longspan bridges. Although not an exhaustive list, notable studies of ambient vibration response analysis of long-span bridges include: Abdel-Gha ar and Housner [1], Abdel-Gha ar and Scanlan [2; 3], Abdel-Gha ar et al [4], Niazy, [5], Fujino et al [6], Jones and Spartz [7], Jones et al [8], Brownjohn et al [9; 10], Chang et al [11], Cunha et al [12], etc.…”

Temperature-based structural health monitoring baseline for long-span bridges

“…One of the most common methods for SHM of long-span bridges is an ambient vibration-based approach (VBSHM) [8][9][10][11][12][13][14][15]. This method provides an overall characterization through tracking the modal parameters of the structure, and while it has enjoyed significant attention over the last several decades, it has many widely recognized drawbacks [16].…”

Impacts of Epistemic (Bias) Uncertainty on Structural Identification of Constructed (Civil) Systems

“…Overcoming this challenge requires that the recent advances in St-ID, control and monitoring of manufactured systems be adapted to explicitly recognize and address the unique attributes of constructed systems. An example of this type of development is the recent progress associated with operational (or output-only) modal analysis, which recognizes the cost and difficulty of performing forced vibration tests on large constructed systems (see, for example, Brownjohn et al, 1992;Fujino et al, 1999;Wenzel and Pichler, 2005). In addition, several researchers have developed St-ID approaches that explicitly address aleatory uncertainty (uncertainty due to natural randomness), which can be significant for constructed systems (Bucher et al, 2003;Yuen and Katafygiotis, 2002;Beck and Katafygiotis, 1998;Beck, 1990).…”