Non-linear buffeting response analysis of long-span suspension bridges with central buckle

The rigid central buckle employed in the Runyang Suspension Bridge (RSB) was the first time it was used in a suspension bridge in China. By using a spectral representation method and FFT technique combined with measured data,a 3D fluctuating wind field considering the tower wind effect is simulated. A novel FE model for buffeting analysis is then presented,in which a specific user-defined Matrix27 element in ANSYS is employed to simulate the aeroelastic forces and its stiffness or damping matrices are parameterized by wind velocity and vibration frequency. A nonlinear time history analysis is carried out to study the influence of the rigid central buckle on the wind-induced buffeting response of a long-span suspension bridge. The results can be used as a reference for wind resistance design of long-span suspension bridges with a rigid central buckle in the future.

Analysis of the Quasi-Static Buffeting Responses of Transmission Lines to Moving Downburst

Downburst event is identified as a major cause to failure of transmission lines in non-coastal regions.In this paper,a novel nonlinear analytical frame for quasi-static buffeting responses of hinged and multi-span insulator-line systems are derived based on the theory of cable structure.The closed-form solutions are presented and applied to predict nonlinear response including displacements and other reactions of the system subjected to a moving downburst wind in a case study.Accuracy and efficiency of the derived analytical frame are validated via comparisons with results from finite element method.

Investigation of Turbulence Effects on the Aeroelastic Properties of a Truss Bridge Deck Section

This paper presents the flutter derivatives （FDs） extracted from a stochastic system identification （SSI） method under different turbulent flows, The objective of the study is to investigate the effects of oncoming turbulence on the flutter of suspended long-span bridges using a section model wind-tunnel test, Several wind-tunnel tests were performed on a truss bridge deck section with different oncoming turbulent properties involving reduced turbulence intensities and turbulent scales. This study includes an investigation of the effect of oncoming flows on modal dynamic responses. The transient and buffeting response data from the wind-tunnel test are analyzed using the system identification technique in extracting FDs, and the difficulties involved in this method are discussed. The time-domain SSI is applied to extract all FDs simultaneously from one and two degree-of-freedom （1DOF and 2DOF） systems, Finally, the results under different conditions are discussed and conclusions are formed.

Effects of Tuned Mass Damper on Wind-Induced Vibration of Free Standing Pylon by Wind Tunnel Test

In order to assess the effects of tuned mass dampers （TMDs） on wind actions, an aeroelastic model with a scale of 1：60 was constructed. Tests were performed in an atmospheric boundary layer wind tunnel to investigate the buffeting response of the pylon with a TMD fixed by a wire rope instead of a spring. The model was tested under different levels of damping. The experimental and numerical results showed that with the TMD in the optimal condition, the buffeting response was reduced by 47%.

Effects of non-stationary wind velocity models on buffeting performance of closed-box girder suspension bridges

Non-stationary characteristic in nature wind has a great effect on buffeting performance of long-span bridges.The influence of key parameters in non-stationary wind velocity models on nonlinear buffeting responses of a super long-span suspension bridge was investigated in this paper.Firstly,four non-stationary wind velocity models are established by combing the time-varying average wind velocity with an exponential function and the fluctuating wind velocity with four modulation functions,respectively.These non-stationary wind velocity models have obvious non-stationary characteristics and then are validated by the classical power spectrum densities.Finally,three displacement responses of the bridge deck under four different independent variables ofβin the exponential function and four modulation functions were compared,respectively.Results show that the turbulence intensities using two non-uniform modulation functions(NMF)are larger than those using uniform modulation functions(uMF).Moreover,the root mean square(RMS)values of three displacement responses increase with the decrease ofβ.Besides,the RMS values of three displacement under two NMFs are larger than those under two uMFs,and their RMS values under the second uMF are the smallest.

Safety and serviceability assessment for high-rise tower crane to turbulent winds

Tower cranes are commonly used facilities for the construction of high-rise structures.To ensure their workability,it is very important to analyze their response and evaluate their condition under extreme conditions.This paper proposes a general scheme for safety and serviceability assessment of high-rise tower crane to turbulent winds based on time domain buffeting response analysis.Spatially correlated wind velocity field at the location of the tower crane was first simulated using an algorithm for generating the time domain samples of a stationary,multivariate stochastic process according to some prescribed spectral density matrix.The buffeting forces applied to the structure were computed according to the above-simulated wind velocity fluctuations and the lift,drag,and moment coefficients obtained from a CFD computation.Those spatially correlated loads were then fed into a well calibrated finite element model and the nonlinear time history analysis was conducted to compute structural buffeting response.Compared with structural onsite response measurement,the computed response using the proposed method has good precision.The proposed method is then adopted for analyzing the buffeting response of an in-use tower crane under the design wind speed and the maximum operational wind speed for safety and serviceability assessment.