Ambient Vibration of Long-Span Cable-Stayed Bridge

Chang, Chin-Chen; Chang, Tienchong; Zhang, Q. W.

doi:10.1061/(asce)1084-0702(2001)6:1(46)

Cited by 98 publications

(41 citation statements)

References 13 publications

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“…However, there are many good papers devoted to modal testing of civil engineering structures [19][20][21][22][23][24]. As the modal testing technology has developed and been accepted as a way for reliable estimation of dynamic properties, more researchers have started to pay attention to the correlation between the initial FE model and experimental results from real-life as-built structures.…”

Section: Applications In Civil Structural Engineeringmentioning

confidence: 99%

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Finite element modelling and updating of a lively footbridge: The complete process

Živanović

Pavić

Reynolds

2007

Journal of Sound and Vibration

127

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The finite element (FE) model updating technology was originally developed in the aerospace and mechanical engineering disciplines to automatically update numerical models of structures to match their experimentally measured counterparts. The process of updating identifies the drawbacks in the FE modelling and the updated FE model could be used to produce more reliable results in further dynamic analysis. In the last decade, the updating technology has been introduced into civil structural engineering. It can serve as an advanced tool for getting reliable modal properties of large structures. The updating process has four key phases: initial FE modelling, modal testing, manual model tuning and automatic updating (conducted using specialist software). However, the published literature does not connect well these phases, although this is crucial when implementing the updating technology. This paper therefore aims to clarify the importance of this linking and to describe the complete model updating process as applicable in civil structural engineering. The complete process consisting the four phases is outlined and brief theory is presented as appropriate. Then, the procedure is implemented on a lively steel box girder footbridge. It was found that even a very detailed initial FE model underestimated the natural frequencies of all seven experimentally identified modes of vibration, with the maximum error being almost 30%. Manual FE model tuning by trial and error found that flexible supports in the longitudinal direction should be introduced at the girder ends to improve correlation between the measured and FE-calculated modes. This significantly reduced the maximum frequency error to only 4%. It was demonstrated that only then could the FE model be automatically updated in a meaningful way. The automatic updating was successfully conducted by updating 22 uncertain structural parameters. Finally, a physical interpretation of all parameter changes is discussed. This interpretation is often missing in the published literature. It was found that the composite slabs were less stiff than originally assumed and that the asphalt layer contributed considerably to the deck stiffness. This paper has been published under the following reference:Živanović, S., Finite element modelling and updating of a lively footbridge: the complete process.

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Section: Applications In Civil Structural Engineeringmentioning

confidence: 99%

“…water pipe -density (17) water pipe -density (18) 30mm steel+concrete -dynamic modulus (10) -density (15) -composite plate thickness (24) 15mm steel+concrete -dynamic modulus (11) -density (16) -composite plate thickness (25) composite slabs in column area …”

Section: Parameter Selectionmentioning

confidence: 99%

Finite element modelling and updating of a lively footbridge: The complete process

Živanović

Pavić

Reynolds

2007

Journal of Sound and Vibration

127

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“…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.…”

Section: Motivation and Technical Challengesmentioning

confidence: 99%

“…Re( 2i ) 2 + Im( 2i ) 2 ; i= 1; : : : ; n 1 (11) where Re(·) means the real part of a complex number, and Im(·) the imaginary part. The 2n 1 dimension complex eigenvectors z k (k = 1; 2; : : : ; 2n 1 ) of 2n 1 numbers also come in complex conjugate pairs.…”

Section: Identiÿcation Of Modal Frequencies Damping Coe Cients and Mmentioning

confidence: 99%

System identification of the Vincent Thomas suspension bridge using earthquake records

Smyth

Pei

Masri

2003

Earthq Engng Struct Dyn

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SUMMARYThe Vincent Thomas Bridge in the Los Angeles metropolitan area, is a critical artery for commercial tra c ow in and out of the Los Angeles Harbor, and is at risk in the seismically active Southern California region, particularly because it straddles the Palos Verdes fault zone. A combination of linear and non-linear system identiÿcation techniques is employed to obtain a complete reduced-order, multiinput-multi-output (MIMO) dynamic model of the Vincent Thomas Bridge based on the dynamic response of the structure to the 1987 Whittier and 1994 Northridge earthquakes.Starting with the available acceleration measurements (which consists of 15 accelerometers on the bridge structure and 10 accelerometers at various locations on its base), an e cient least-squares-based time-domain identiÿcation procedure is applied to the data set to develop a reduced-order, equivalent linear, multi-degree-of-freedom model. Although not the main focus of this study, the linear system identiÿcation method is also combined with a non-parametric identiÿcation technique, to generate a reduced-order non-linear mathematical model suitable for use in subsequent studies to predict, with good ÿdelity, the total response of the bridge under arbitrary dynamic environments.Results of this study yield measurements of the equivalent linear modal properties (frequencies, mode shapes and non-proportional damping) as well as quantitative measures of the extent and nature of nonlinear interaction forces arising from strong ground shaking. It is shown that, for the particular subset of observations used in the identiÿcation procedure, the apparent non-linearities in the system restoring forces are quite signiÿcant, and they contribute substantially to the improved ÿdelity of the model. Also shown is the potential of the identiÿcation technique under discussion to detect slight changes in the structure's in uence coe cients, which may be indicators of damage and degradation in the structure being monitored. Di culties associated with accurately estimating damping for lightly damped long-span structures from their earthquake response are discussed. The technical issues raised in this paper indicate the need for added spatial resolution in sensor instrumentation to obtain identiÿed mathematical models of structural systems with the broadest range of validity.

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“…In recent years, the modal characteristics of bridges in case of various excitation forces (traffic, wind, and earthquake) have been investigated by various researchers since bridges serve a major role for transportation network. The target of these studies were mostly to (1) control the accuracy of the analytical modelling of the bridge to use it during the life span of the bridge and/or (2) carry out a long term monitoring under service loads (AbdelGhaffar and Scanlan 1985;Chang et al 2001;Hiesh et al 2006;Huffman et al 2006;Gentile and Gallino 2008;Picozzi et al 2010;Apaydin et al 2012). Furthermore, in case of identifying the dynamic characteristics of cultural heritage structures, vibration-based methods are of vital importance since these methods respond to the preservation needs of these types of structures (Ivorra and Pallares 2006;De Stefano 2007;D'ambrisi et al 2012;Foti et al 2012;Asteris et al 2014;Votsis et al 2012;Chrysostomou et al 2005Chrysostomou et al , 2008.…”

Section: Introductionmentioning

confidence: 99%

Field testing of substandard RC buildings through forced vibration tests

Göksu

Inci

Demir

et al. 2015

Bull Earthquake Eng

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In this study, forced vibration tests were conducted on two full-scale substandard reinforced concrete (RC) buildings to obtain the dynamic characteristics (modal frequencies and damping ratios) of these buildings. These tests were carried out before and after quasi-static lateral loading cycles. Through quasi-static cyclic loading, which was applied only in x direction of the buildings, the buildings were forced to experience specific damage states in a controlled manner. The original aspect of the study is investigating the rates of changes of the dynamic characteristics with the increasing damage. According to the test results, it was observed that modal frequencies tend to decrease while damping ratios for different modes tend to increase with the increasing levels of damage. In addition, finite element models of the buildings were established and modal analyses were performed for the undamaged state. Model updating was carried out in order to determine the optimal means of improving the accuracies of the finite element models of the test buildings. Experimentally identified modal frequencies of the buildings and those computed using finite element model were found to be consistent. Since the buildings tested in this study represent most of the existing substandard RC buildings in Turkey, determining the changes in dynamic characteristics with the increasing damage would be useful in the decision of demolishing/retrofitting of these types of buildings after potential future earthquakes.

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Ambient Vibration of Long-Span Cable-Stayed Bridge

Cited by 98 publications

References 13 publications

Finite element modelling and updating of a lively footbridge: The complete process

Finite element modelling and updating of a lively footbridge: The complete process

System identification of the Vincent Thomas suspension bridge using earthquake records

Field testing of substandard RC buildings through forced vibration tests

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