Ambient Vibration Measurements of the Humber Suspension Bridge and Com Parison With Calculated Characteristics

Brownjohn, James; Dumanoǧlu, A. A.; Severn, RT; Taylor, CA

doi:10.1680/iicep.1987.335

Cited by 51 publications

(25 citation statements)

References 7 publications

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“…For example, the SDOF half-power bandwidth method using ambient testing response data tends to produce higher damping because of the averaging during data processing and the impossibility to have ideally stationary input necessary for ambient testing [109]. Also it can neither produce good damping estimate for closely spaced modes nor give insight into the amplitude dependence phenomenon.…”

Section: New Measurement Techniquesmentioning

confidence: 99%

Vibration serviceability of footbridges under human-induced excitation: a literature review

Živanović

Pavić

Reynolds

2005

Journal of Sound and Vibration

521

315

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Increasing strength of new structural materials and longer spans of new footbridges, accompanied with aesthetic requirements for greater slenderness, are resulting in more lively footbridge structures. In the past few years this issue attracted great public attention. The excessive lateral sway motion caused by crowd walking across the infamous Millennium Bridge in London is the prime example of the vibration serviceability problem of footbridges. In principle, consideration of footbridge vibration serviceability requires a characterisation of the vibration source, path and receiver. This paper is the most comprehensive review published to date of about 200 references which deal with these three key issues.The literature survey identified humans as the most important source of vibration for footbridges. However, modelling of the crowd-induced dynamic force is not clearly defined yet, despite some serious attempts to tackle this issue in the last few years.The vibration path is the mass, damping and stiffness of the footbridge. Of these, damping is the most uncertain but extremely important parameter as the resonant behaviour tends to govern vibration serviceability of footbridges.A typical receiver of footbridge vibrations is a pedestrian who is quite often the source of vibrations as well. Many scales for rating the human perception of vibrations have been found in the published literature. However, few are applicable to footbridges because a receiver is not stationary but is actually moving across the vibrating structure.During footbridge vibration, especially under crowd load, it seems that some form of humanstructure interaction occurs. The problem of influence of walking people on footbridge vibration properties, such as the natural frequency and damping is not well understood, let alone quantified.Finally, there is not a single national or international design guidance which covers all aspects of the problem comprehensively and some form of their combination with other published information is prudent when designing major footbridge structures. The overdue update of the current codes to reflect the recent research achievements is a great challenge for the next 5-10 years. Abbreviations:ASD-auto spectral density; DLF-dynamic load factor; DOF-degree of freedom; FE-finite element;FRF-frequency response function; MDOF-multiple-degree-of-freedom;MTMD-multiple tuned mass damper; RMS-root-mean-square;SDOF-single-degree-of-freedom; TLD-tuned liquid damper; TMD-tuned mass damperThis paper has been published under the following reference:Živanović, S., Vibration serviceability of footbridges under human-induced excitation: a literature review.

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Section: New Measurement Techniquesmentioning

confidence: 99%

Vibration serviceability of footbridges under human-induced excitation: a literature review

Živanović

Pavić

Reynolds

2005

Journal of Sound and Vibration

521

315

View full text Add to dashboard Cite

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“…The slipformed reinforced concrete towers rise 155.5 m above the caisson foundations and carry the two main cables with nominal sag of 115.5 m. The bridge is exposed to prevailing south-westerly cyclonic winds that can reach hurricane force (exceeding 32.7 m/sec), with atmospheric temperatures ranging from -10° C to 30° C. Humber has been the subject of several academic investigations focusing on dynamic performance. Ambient vibration surveys were carried out in 1985 by University of Bristol and Building Research Establishment (BRE), (Brownjohn et al 1987;Littler 1992), BRE again in 1988 (Littler & Woods 1989) and most recently in 2008 by University of Sheffield and helpers (Brownjohn et al 2010).…”

Section: Humber Bridge: Structural Details and Previous Studiesmentioning

confidence: 99%

Structural identification of Humber Bridge for performance prognosis

Rahbari¹,

Jin²,

Koo³

2015

Smart Structures and Systems

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Structural identification or St-Id is 'the parametric correlation of structural response characteristics predicted by a mathematical model with analogous characteristics derived from experimental measurements'. This paper described a St-Id exercise on Humber Bridge that adopted a novel two-stage approach to first calibrate and then validate a mathematical model. This model was then used to predict effects of wind and temperature loads on global static deformation that would be practically impossible to observe.The first stage of the process was an ambient vibration survey in 2008 that used operational modal analysis to estimate a set of modes classified as vertical, torsional or lateral. In the more recent second stage a finite element model (FEM) was developed with an appropriate level of refinement to provide a corresponding set of modal properties. A series of manual adjustments to modal parameters such as cable tension and bearing stiffness resulted in a FEM that produced excellent correspondence for vertical and torsional modes, along with correspondence for the lower frequency lateral modes.In the third stage traffic, wind and temperature data along with deformation measurements from a sparse structural health monitoring system installed in 2011 were compared with equivalent predictions from the partially validated FEM.The match of static response between FEM and SHM data proved good enough for the FEM to be used to predict the un-measurable global deformed shape of the bridge due to vehicle and temperature effects but the FEM had limited capability to reproduce static effects of wind. In addition the FEM was used to show internal forces due to a heavy vehicle to to estimate the worst-case bearing movements under extreme combinations of wind, traffic and temperature loads.The paper shows that in this case, but limitations, such a two-stage FEM calibration/validation process can be an effective tool for performance prognosis. KeywordsSuspension bridge structural identification model updating modal test temperature vehicle wind static 2

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“…The original ambient vibration study (Brownjohn et al 1987) and the 1990/1991 extended monitoring (Brownjohn et al 1994) served the purpose of validating simulation software to be used for analysis and design of other bridges. Specifically, the finite element analysis procedure validated in the 1985 test was used for studying seismic response of the two Bosporus crossings (Dumanoglu et al 1992;Dumanoglu and Severn 1987), while the 1990/1991 study validated procedures for simulating the in-wind performance of the proposed Messina Straits Bridge (Diana et al 2003).…”

Section: Previous Measurement Campaignsmentioning

confidence: 99%

“…The validated finite element model (Brownjohn et al 1987) demonstrated that with all bearings behaving as perfect sliding and pinned joints, the first vertical vibration mode would be anti-symmetric, with frequency 0.108 Hz, whereas with either end not free to slide the first mode is the 'symmetric' one. In reality the symmetric mode always appears first at 0.116 Hz, with the anti-symmetric mode at 0.15 Hz during all vibration measurements since 1985.…”

Section: Bearing Influence On Dynamic Performancementioning

confidence: 99%