Estimation of Damping Ratio of Cable‐Stayed Bridges for Seismic Design

Kawashima, Koichiro; Unjoh, Shigeki; Tunomoto, Meguru

doi:10.1061/(asce)0733-9445(1993)119:4(1015)

Cited by 33 publications

(25 citation statements)

References 1 publication

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“…While this will never be able to model the considerable complexity of the various mechanisms at play (Kawashima et al, 1990(Kawashima et al, , 1993Yamaguchi and Ito, 1997), careful selection of an equivalent viscous damping ratio that is suitable for the structure, level and type of loading, and expected response provides a reasonable approximation. Various modal-combination rules have been proposed for non-classically damped structures (e.g.…”

Section: Discussion Of the Application To Cable-stayed Bridgesmentioning

confidence: 99%

The use of modal-combination rules with cable-stayed bridges

Walker¹,

Stafford²

2010

Proceedings of the Institution of Civil Engineers - Bridge Engi

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Modal superposition techniques such as the responsespectrum method (RSM) can be used to quickly estimate the peak response of a structure to earthquake-induced vibration and, as such, are widely used in preliminary design. Modal-combination rules for use with the RSM are typically founded on assumptions of linear structural behaviour, well-separated natural modes, classical damping and stationary excitation. By contrast, the response of cable-stayed bridges is known to be nonlinear with three-dimensional orthogonal mode shapes that can be coupled and closely spaced. Furthermore, it is widely known that the use of stationary stochastic processes for modelling earthquake excitation is a firstorder approximation and there is thus sufficient reason to doubt the validity of the RSM for estimating the response of cable-stayed bridges. This paper critiques the historical development and theoretical consistency of popular modal-combination rules with a view to assessing their suitability for estimating the response of cable-stayed bridges and their relative performance is investigated using an example finite-element model. In many cases, the more sophisticated modal-combination rules can be reliably employed; however, numerous scenarios are envisaged where such rules are likely to be inaccurate and caution is advised against their use under these circumstances.

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Section: Discussion Of the Application To Cable-stayed Bridgesmentioning

confidence: 99%

The use of modal-combination rules with cable-stayed bridges

Walker¹,

Stafford²

2010

Proceedings of the Institution of Civil Engineers - Bridge Engi

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show abstract

“…In the case of cable-stayed bridges in which the dynamic amplification due to the deck-tower interaction is not significant, the factor k R may be substituted by k static R D L S =.L P C L S / in expressions (2) and (3) in order to avoid the MRSA. This is relevant to the short-span bridge considered in this work, with L P D 200 m (Section 5).…”

Section: Design Of Dampers With Optimal Ductilitymentioning

confidence: 99%

“…the large structural flexibility of cable-stayed bridges, and (4) these structures present inherently low damping values [2] and adding supplemental sources of energy dissipation is recommendable. Some of the most important cable-supported bridges recently constructed in seismic-prone areas include passive SDS, as summarised in Table I.…”

Section: Introductionmentioning

confidence: 99%

Design of hysteretic dampers with optimal ductility for the transverse seismic control of cable‐stayed bridges

Cámara

Cristantielli

Suárez

et al. 2017

Earthq Engng Struct Dyn

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Cable-stayed bridges require a careful consideration of the lateral force exerted by the deck on the towers under strong earthquakes. This work explores the seismic response of cable-stayed bridges with yielding metallic dampers composed of triangular plates (TADAS) that connect the deck with the supports in the transverse direction. A design method based on an equivalent single-degree of freedom approximation is proposed. This is proved valid for conventional cable-stayed bridges with 200 and 400 m main spans, but not 600 m. The height of the plates is chosen to (1) achieve a yielding capacity that limits the maximum force transmitted from the deck to the towers, and to (2) control the hysteretic energy that the dampers dissipate by defining their design ductility. In order to select the optimal ductility and the damper configuration, a multi- objective response factor that accounts for the energy dissipation, peak damper displacement and low-cycle fatigue is introduced. The design method is applied to cable-stayed bridges with different spans and deck- support connections. The results show that the dissipation by plastic deformation in the dampers prevents significant damage in the towers of the short-to-medium span bridges under the extreme seismic actions . However, the transverse response of the towers in the bridge with 600 m span is less sensitive to the TADAS dampers

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“…To obtain a general method for evaluating the modal damping ratios of cables, some scholars have tried to propose calculation methods from the view of energy consumption because the main function of modal damping is to dissipate the vibration energy. For instance, Kawashima proposed a method of evaluating the energy dissipation function for each substructure of cablestayed bridges through a free-oscillation test of a cable-stayed bridge model [1]. However, the explicit expression for the modal damping of stayed-cables was not deduced in the study.…”

Section: Review Of Previous Workmentioning

confidence: 99%

Damping properties of FRP cables for long-span cable-stayed bridges

Yang

Wang

et al. 2015

Mater Struct

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In this study, the damping properties of carbon fiber reinforced polymer (CFRP) and basalt fiber reinforced polymer (BFRP) cable potentially applied in long-span cable-stayed bridges were simulated and evaluated based on experimental data and theoretical derivations. The modal shapes were first identified according to a previous dynamic test on FRP cables, based on which the modal damping ratios of the in-plane vibration were estimated by the structural damping model of mode-dependence. Meanwhile, the modal damping ratios of the out-of-plane vibration were evaluated by the combined Rayleigh and frequency independent damping (CRFID) model. The results show that (1) the modified equation for the modal damping ratio validated by the results of inplane vibration of the steel cable can be used for modeling the damping ratios of FRP cables, (2) the coefficients of dynamic strain damping energy of CFRP and BFRP cables were derived by backward calculating and fitting the experimental data, which can represent the damping difference among each material, and (3) the modal damping ratios of the outof-plane modes of different stayed cables were fitted by the CRFID model and show good agreement with the test results.

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Estimation of Damping Ratio of Cable‐Stayed Bridges for Seismic Design

Cited by 33 publications

References 1 publication

The use of modal-combination rules with cable-stayed bridges

The use of modal-combination rules with cable-stayed bridges

Design of hysteretic dampers with optimal ductility for the transverse seismic control of cable‐stayed bridges

Damping properties of FRP cables for long-span cable-stayed bridges

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