Experimental investigation of flutter characteristics of shallow<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e430" altimg="si17.svg"><mml:mi>Π</mml:mi></mml:math>section at post-critical regime

Tang, Yu; Hua, Xugang; Chen, Z.Q.; Zhou, Youhe

doi:10.1016/j.jfluidstructs.2019.05.010

Cited by 44 publications

(14 citation statements)

References 37 publications

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“…The solving of Equation (29) was performed by an explicit Newmark-β method through an iteration procedure. During the calculation, the amplitude-dependent effect of structural damping ratios ( α0 ξ , h0 ξ ) and frequencies ( t0 ω , h0 ω ) were also considered, for which one can refer to the previous studies by Gao and Zhu [6]. Figure 22 shows the calculated post-critical LCOs for Case B1 when U* = 7.785.…”

Section: Aerodynamic Nonlinearitymentioning

confidence: 99%

“…Experimental and numerical evidences suggest that the aerodynamic nonlinearity under large amplitude will introduce a secondary stabilizing effect and the flutter performance manifests as a soft-type nonlinear flutter instability [2][3][4][5][6][7][8][9][10][11][12][13][14]. When wind velocity exceeds beyond linear flutter boundary, there is a possible existence of nonlinear post-critical limit cycle oscillation (LCOs) due to the aerodynamic nonlinearity.…”

Section: Introductionmentioning

confidence: 99%

“…The aerodynamic nonlinearities in post-critical states have attracted wide attention in recent years [2][3][4][5][6][7][8][9][10][11][12][13][14]. The reported post-flutter phenomena vary with different deck shapes.…”

Section: Introductionmentioning

confidence: 99%

“…The torsional flutter was found to be a non-divergent type with a gradual increase of torsional amplitude with velocity beyond flutter onset velocity for three different geometrical shapes of edge girders. Recently, the nonlinear post-flutter behaviors of two-edge girders were also extensively studied by Zheng et al [5] and Tang et al [6]. Zheng et al [5] investigated the aerodynamic mitigation measures of the soft-type flutter of a Π-shaped bridge deck.…”

Section: Introductionmentioning

confidence: 99%

“…They found that the post-flutter vibration amplitude was sensitive to the wind fairings and auxiliary facilities. Tang et al [6] studied the post-critical response of a shallow Π shaped-section and found that the stable LCO amplitudes were sensitive to wind attack angle and structural damping. Gao et al [7] studied the post-flutter behavior of a twin-side-girder bridge deck and found the sectional model exhibits significant post-critical LCOs with very slight heave-torsion coupling effects.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Experimental Investigation on the Nonlinear Coupled Flutter Motion of a Typical Flat Closed-Box Bridge Deck

Gao

Zhu

Wang

et al. 2020

Sensors

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The nonlinear post-flutter instabilities were experimentally investigated through two-degree-of-freedom sectional model tests on a typical flat closed-box bridge deck (width-to-depth ratio 9.14). Laser displacement sensors and piezoelectric force balances were used in the synchronous measurement of dynamic displacement and aerodynamic force. Beyond linear flutter boundary, the sectional model exhibited heave-torsion coupled limit cycle oscillation (LCOs) with an unrestricted increase of stable amplitudes with reduced velocity. The post-critical LCOs vibrated in a complex mode with amplitude-dependent mode modulus and phase angle. Obvious heaving static deformation was found to be coupled with the large-amplitude post-critical LCOs, for which classical quasi-steady theory was not applicable. The aerodynamic torsional moment and lift during post-critical LCOs were measured through a novel wind-tunnel technique by 4 piezoelectric force balances. The measured force signals were found to contain significantly higher-order components. The energy evolution mechanism during post-critical LCOs was revealed via the hysteresis loops of the measured force signals.

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Section: Aerodynamic Nonlinearitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Experimental Investigation on the Nonlinear Coupled Flutter Motion of a Typical Flat Closed-Box Bridge Deck

Gao

Zhu

Wang

et al. 2020

Sensors

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Regularised Volterra series models for modelling of nonlinear self-excited forces on bridge decks

et al. 2023

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Volterra series models are considered an attractive approach for modelling nonlinear aerodynamic forces for bridge decks since they extend the convolution integral to higher dimensions. Optimal identification of nonlinear systems is a challenging task since there are typically many unknown variables that need to be determined, and it is vital to avoid overfitting. Several methods exist for identifying Volterra kernels from experimental data, but a large class of them put restrictions on the system inputs, making them infeasible for section model tests of bridge decks. A least-squares identification method does not restrict the inputs, but the identified model often struggles with noisy (non-smooth) kernels, which is deemed to be unphysical and a sign of overfitting. In this work, regularised least-squares identification is introduced to improve the performance of model identification using least-squares. Standard Tikhonov regularisation and other penalty techniques that impose decaying kernels are also explored. The performance of the methodology is studied using experimental data from wind tunnel tests of a twin deck section. The regularised Volterra models show equal or better results in terms of modelling the self-excited forces, and the regularisation makes the models less prone to overfitting.

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Motion-amplitude-dependent nonlinear VIV model and maximum response over a full-bridge span

Zhang

2023

Nonlinear Dyn

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Nonlinear vortex-induced vibration (VIV) performances of a bridge section are investigated in terms of motion amplitude (𝑦 𝑇 ) dependent energy-trapping properties.Energy-trapping properties of a model undergoing a full-process from still to a limit cycle oscillation (LCO) state are determined. A van der Pol-type model is used to describe the amplitude-dependent VIV performances. Nonlinear parameter-amplitude relations, 𝜀-𝑦 𝑇 and 𝜉 𝜀 -𝑦 𝑇 , are established. Nonlinear aerodynamic damping during the VIV lock-in range is separated into two parts: the initial damping which varies with the reduced wind speed, and the 𝜀-related part which varies with both the reduced wind speed and the motion amplitude. The initial aerodynamic damping determines the threshold of VIV, while the 𝜀 -related part dominates the evolution process and the LCO. The identified nonlinear analytical model is capable of predicting VIV responses at higher mechanical damping ratios. The energy-trapping properties of a section model in time are transformed into nonlinear distribution properties in space along an elongated 3-D elastic bridge span. According to this "time-space" transformation, the convection coefficient, which links the maximum response of a 3-D structure with that of a 2-D sectional model can be determined. Compared with a constant-parameter analytical model, a nonlinear model results in significantly larger convection coefficients. Finally, parameter overflowing phenomena are revealed.

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Experimental investigation of flutter characteristics of shallowΠsection at post-critical regime

Cited by 44 publications

References 37 publications

Experimental Investigation on the Nonlinear Coupled Flutter Motion of a Typical Flat Closed-Box Bridge Deck

Experimental Investigation on the Nonlinear Coupled Flutter Motion of a Typical Flat Closed-Box Bridge Deck

Regularised Volterra series models for modelling of nonlinear self-excited forces on bridge decks

Motion-amplitude-dependent nonlinear VIV model and maximum response over a full-bridge span

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