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Li S.-Y.,Hunan University | Sun W.-F.,Hunan University | Sun W.-F.,China Zhongtie Major Bridge Reconnaissance and Design Institute Co Ltd | Chen Z.-Q.,Hunan University
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2013

To investigate the aerodynamic forces acting on the stay cable and the rivulet during rain-wind induced vibrations, a cable model with a diameter of 350 mm was made. And 5 cases of wind tunnel tests were carried out to measure wind pressures on the cable and rivulet by using forced vibration system. The effects of the rivulet and the test model vibrations on the mean and fluctuating wind pressure coefficients, the mean aerodynamic force coefficients and the power spectral density of fluctuating lift coefficients were systematically studied. Moreover, the validity of quasi-steady theory in rain-wind induced vibrations was checked out. The results indicate that quasi-steady theory can reflect the main characteristics of the wind forces on the cable and the rivulet; the oscillation of the rivulet and vertical vibration of the cable do not change their mean wind force coefficients, and there is a fast drop of mean lift coefficient at the attack angle of 60°; the oscillation of the rivulet on the cable surface heavily affects the fluctuating aerodynamic force coefficients, while the vertical vibration of the cable has a little influence; furthermore, the presence of the rivulet decreases the frequency of vortex shedding. Source


Zhan H.,China Zhongtie Major Bridge Reconnaissance and Design Institute Co Ltd | Li W.,Huazhong University of Science and Technology | Li L.,Huazhong University of Science and Technology
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2010

To comprehensively investigate the effect of corner modification on aerodynamic forces, this paper presents the calculations of characteristics of a square sectioned cylinder with sharp, chamfered or rounded corners in two dimensional incompressible uniform cross flow by using RSM method of FLUENT. The numerical simulation focused on investigating the characteristics of the drag force, lift force, moment force, Strouhal number and typical flow patterns. It is found that the incidence of separation is often rather sensitive to small change in the shape of the solid body, particularly when the pressure distribution is strongly affected by this change in shape. So wind loading can be reduced by controlling the separated flow through modifying corner shapes. The numerical simulation results are in good agreement with the experiment results and rounded corners has the best aerodynamic quantities. Source


Li H.,China Earthquake Administration | Li H.,Wuhan Institute of Earthquake Engineering | Li L.,China Zhongtie Major Bridge Reconnaissance and Design Institute Co Ltd | Feng Q.,China Earthquake Administration | Feng Q.,Wuhan Institute of Earthquake Engineering
Journal of Earthquake Engineering and Engineering Vibration | Year: 2012

The effect of the long-period filter cut-off, Tc, on spectral displacements is analysed using the NGA database of the Pacific Earthquake Engineering Research Center. Long-period spectral displacements would be suppressed badly, if a short Tc is chosen. Strong ground motion accelerograms with reliable period up to at least 10s are selected to investigate the characteristics of displacement response spectra at long periods. The results indicate that the period, in which the spectral displacement culminates, is a significant parameter to control long-period spectral ordinates. This parameter can't be affected obviously by site condition and magnitude,but greatly depends on epicentral distance with linear relation. The maximum amplification factor of displacement spectrum fluctuates slightly, and can be treated as a constant. A transition region is suggested to insert between velocity-sensitive region and displacement-sensitive region to fit for displacement spectrum, and the values of some parameters are proposed in this paper. Source


Liu M.-Y.,Hubei Engineering University | Wang S.,Hubei Engineering University | Zhang Q.,China Zhongtie Major Bridge Reconnaissance and Design Institute Co Ltd
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2013

The schemes of non-navigable span inshallow water area of Hongkong-Zhuhai-Macau bridge use 85 m span steel-concrete composite continuous beams with 6~7 spans one continuous unit and the designed service life of the bridge will be 120 years. The bridge use the construction technology of large segment integral lifting, converting simply-support in continuous , fulcrum lifting-up and fallbacking, stretching prestress of bridge deck in negative moment area. The ANSYS software is used to build 3-D and refined finite model of composite continuous beams with single span to research force distribution of shear studs in lognitudinal and transverse direction of composite continuous beams under dead load and live load.The side span with the shear stdus under the most unfavorable load condition is choosed and spring element combin39 is used to calculate accurately drawing force of every shear stdus. The calculation results of comparison of two section types show that the shear stdus between concrete deck and steel box girder of section with longitudinal beam has better connectivity than section without longitudinal beam. Source


Chen W.,Huazhong University of Science and Technology | Chen W.,Wuhan Polytechnic University | Wang B.,Huazhong University of Science and Technology | Zhan H.,China Zhongtie Major Bridge Reconnaissance and Design Institute Co Ltd | Zhou L.,Wuhan Polytechnic University
Kybernetes | Year: 2013

Purpose: Denoising of the vibration signal is crucial to identify a structure's damage. Based on noise frequency character, the "real" vibration signal can be gotten. The purpose of this paper is to propose a novel method for denoising a signal based on the wavelet transform. Design/methodology/approach: The vibration signal with noise which can be collected by wireless network is decomposed by wavelet transform. In order to select optimal level of wavelet decomposition, based on noise's frequency, power spectral density is used. A soft thresholding method based on minimum mean-variance is used for vibration signal de-noising with Gaussian noise. Findings: A novel method has been described in his paper. Based on the relationship between vibration signal's character and noise frequency, the way to get rid of noise is combined wavelet transform with power spectral density. Originality/value: In order to select optimal level of wavelet decomposition, based on noise's frequency, power spectral density is used. A soft thresholding method based on minimum mean-variance is used for vibration signal denoising with Gaussian noise. © Emerald Group Publishing Limited. Source

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