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Experiments on the effect of helical line on the stay-cable vibration at high Reynolds number

Zhendong yu Chongji/Journal of Vibration and Shock 2018年第14期37卷 175-179页

作者： Liu, Qingkuan Lu, Zhaoliang Tian, Kaiqiang Hu, Bo Ma, Wenyong Structural Health Monitoring and Control Institute Shijiazhuang Tiedao University Shijiazhuang050043 China Hebei Province Key Lab of Structural Health Monitoring and Control Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China Department of Engineering Mechanics Shijiazhuang Tiedao University Shijiazhuang050043 China

Cable is one of the basic construction members of a cable-stayed bridge. The wind loads on cables constitute a high proportion of total wind loads on the bridge, and the wind-induced vibration is an important problem of great concern in bridge design. Through a self-designed vibration test system for stay-cables, the vibration model tests for a rigid stay-cables model with diameter of 120 mm as well as for 25 kinds models of stay-cables wound with helical lines were conducted in a wind *** changing rule of the vibration amplitude along with the Reynolds number was analyzed. The results show that winding a helical line on the cable can reduce the Reynolds number effects on it. When the helical line winding spacing is constant, the amplitude trends to decrease along with the increase of helical line diameter. When the helical line diameter is constant, the amplitude trends to decrease along with the decrease of helical line winding spacing. The vibration stability is improved with the increase of helical line diameter and the decrease of helical line winding spacing. © 2018, Editorial Office of Journal of Vibration and Shock. All right reserved.

关键词： Reynolds number

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Analysis of transverse thermal regime difference of high-speed railway roadbed in seasonally frozen regions 15

Analysis of transverse thermal regime difference of high-spe...

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15th International Conference of the International Association for Computer Methods and Advances in Geomechanics, IACMAG 2017

作者： Zhang, Yuzhi Wen, An Cheng, Boyuan Key Laboratory for Health Monitoring and Control of Large Structures in Hebei Province Shijiazhuang Tiedao University Shijiazhuang Hebei050043 China

The transverse thermal regime differences are widespread for high-speed railway roadbed in seasonally frozen regions. Based on the monitored data of four typical roadbed sections from Harbin-Dalian high-speed railway in seasonally frozen regions of China, the external influence and heat absorption of roadbed different parts are studied quantitatively through the comparisons of the temperature amplitude and average temperature, and then the characteristics of the frost penetration development are analyzed. The temperature variation laws of the coldest and hottest months with depth are also analyzed. On the basis of the above analysis, the influence factors and potential hazards of the transverse differences are discussed. It is stated that: the west shoulders are most influenced by the external environment. The coldest and warmest month temperatures at a certain depth are characterized by a spindle shape. The increase of the latitude and roadbed height may aggravate the transverse thermal regime difference. In addition, the roadbed transverse thermal difference may induce the uneven roadbed deformation, hence, the roadbed stability and the ride comfort of track structure maybe threated. Therefore, the relevant monitoring and deformation mechanics studies should be further reinforced. © 2017 15th International Conference of the International Association for Computer Methods and Advances in Geomechanics

关键词： Deformation

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Construction of stability monitoring and evaluation system for high-speed railway roadbed in cold regions 8

Construction of stability monitoring and evaluation system f...

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8th International Conference on structural health monitoring of Intelligent Infrastructure, SHMII 2017

作者： Zhang, Yuzhi Sun, Baochen Zhao, Weigang Wen, An The Key Laboratory for Health Monitoring and Control of Large Structures in Hebei Province Shijiazhuang Tiedao University Shijiazhuang Hebei050043 China

ISBN: (纸本)9781925553055

Along with the development of economy, the high-graded transportation line project are extending towards the cold regions gradually. The high-speed railway (HSR) in cold regions requires extreme high stability, thus the rigorous enigineering demands challenge the roadbed stability severely. The construction of the automatic monitoring and evaluation system of the HSR roadbed in cold regions, to master the safety conditions in real time, will guarantee the safe operation of high-speed train strongly. Through the characteristics analysis of the HSR roadbed in cold regions, the monitoring indices, static deformation combined with dynamic responses, are determined. The layout plan of monitoring points, which integrates the transverse discontinuity with horizontal continuity, is put forward. On the basis of conquering the continous high-precision collection sensors and technology suitable for the severe environment in cold regions, the automatic continous monitoring system of the HSR roadbed is developed, and the evaluation method of roadbed stability based on the on-site data information mining and numerical model is built. The monitoring system and stability method have realized the continous monitoring and stability evaluation of the Harbin-Dalian HSR under the water-heat-load combined action. This will be conductive to provide the scientific support for the stability change mechanism, the operation and maintenance of the HSR roadbed in cold regions. © 2017 International Society for structural health monitoring of Intelligent Infrastrucure. All rights reserved.

关键词： Railroads

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Effective concrete surface crack detection based on extreme learning machine 8

Effective concrete surface crack detection based on extreme ...

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8th International Conference on structural health monitoring of Intelligent Infrastructure, SHMII 2017

作者： Wang, Baoxian Zhao, Weigang Zhang, Hao Wang, Xinmin Zhang, Guangyuan Structural Health Monitoring and Control Institute Shijiazhuang Tiedao University Shijiazhuang050043 China Key Laboratory for Health Monitoring and Control of Large Structures Shijiazhuang050043 China Collaborative Innovation Center of Large Infrastructure Disaster Prevention and Reduction of Hebei Province China

ISBN: (纸本)9781925553055

Concrete surface crack detection has been an important field for the safety of civil engineering structure. However, under the background of high-density data acquiring demand, the existing crack detecting methods could not obtain the favorable efficiency and capability. In this work, we present a novel concrete surface crack detector for efficiently dealing with the massive crack images. Specifically, discrete cosine transformation is firstly utilized to extract the frequency domain characteristics of concrete surface images. Then, with the calculated image frequency features, an emergent learning technique (i.e., Extreme Learning Machine) is exploited to find the optimal separate hyper-plane between the crack object and backgrounds. Experiments on the crack images from the railway ballast-less track slab validate the effectiveness of the proposed method. © 2017 International Society for structural health monitoring of Intelligent Infrastrucure. All rights reserved.

关键词： Frequency domain analysis

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Effects of the reattachment on dry galloping in the critical Reynolds number range 9

Effects of the reattachment on dry galloping in the critical...

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9th Asia Pacific Conference on Wind Engineering, APCWE 2017

作者： Ma, Wenyong Liu, Qingkuan Liu, Xiaobing Key Laboratory for Health Monitoring and Control of Large Structure Shijiazhuang Tiedao University Hebei province China Department of Wind Science and Engineering Shijiazhuang Tiedao University Shijiazhuang City Hebei Province China

Large amplitude vibrations of circular cylinders in the critical Reynolds number range are reproduced in wind tunnels. Displacements and wind pressure for the cylinders are measured synchronously to reveal the characteristics of aerodynamic force for the vibrating cylinders in a Reynolds number range where flow re-attaches on the rear of the cylinder. Effects of these reattachments on the aerodynamic forces and the vibrations are discussed. The results show that the reattachment can produce unsteady aerodynamic force and excite large amplitude vibration when it forms unstable separation bubble at the early critical Reynolds number range. Once it develops stable separation bubble, the reattachment mitigates the vibrations by creating strong negative aerodynamic damping. © 9th Asia Pacific Conference on Wind Engineering, APCWE 2017. All Rights Reserved.

关键词： Circular cylinders

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Research on Remote Automatic monitoring System of High and Steep Slope Based on FBG Tilt Sensor

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IOP Conference Series: Earth and Environmental Science 2019年第4期267卷

作者： Hongbin Xu Feng Li Weigang Zhao Meng Li Yang Gao Bo Zhang School of Civil Engineering Beijing Jiaotong University Beijing 100044 China School of Civil Engineering Wuhan University Wuhan Hubei 430074 China Structure Health Monitoring and Control Institute Shijiazhuang Tiedao University Shijiazhuang 050043 Hebei China Key Laboratory of Structure Health Monitoring and Control of Hebei Province Shijiazhuang Tiedao University Shijiazhuang Hebei 050043 China

A remote automatic monitoring system for high and steep slope based on FBG tilt sensor was established along Shuohuang railway, and an FBG tilt sensor with a high sensitivity was developed in this monitoring system. The monitoring system is running smoothly, and the monitoring results show that the maximum deformation of the slop is less than 2 mm in the rainy season, slope slip occurs at the location of 9.5 meters above, the overall deformation of slope is small, and the slope is steady.

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Analysis of void-disease detection in ballastless track of high-speed railway based on directional filter 8

Analysis of void-disease detection in ballastless track of h...

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8th International Conference on structural health monitoring of Intelligent Infrastructure, SHMII 2017

作者： Yang, Y. Zhao, W.G. Du, Y.L. Tian, X.S. School of Electrical and Electronic engineering Shijiazhuang Tiedao University Shijiazhuang China Key Laboratory for Health Monitoring and Control of Large Structures in Hebei Province Shijiazhuang Tiedao University Shijiazhuang China

ISBN: (纸本)9781925553055

Owing to the concealment of void disease in cement-asphalt (CA) mortar and the requirements for rapidness, ground penetrating radar (GPR) has a good application prospect in detecting disease on a high-speed railway. Track slab, the covering of the CA mortar layer, is a multi-layer reinforced concrete structure;strong reflection of reinforcement makes disease identification difficult. To solve this problem, directional models were established to study the feature difference of echoes between reinforcement and void disease, and a horizontal filter based on curvelet transform was proposed to identify the void disease in CA mortar. Finally, forward simulation was conducted to validate the performance of the presented algorithm. Results show that the horizontal filter method contributes to the identification of void diseases in the CA mortar layer which were located in the middle of the reinforcement group. This study promotes the application of GPR on disease detection in a high-speed railway. © 2017 International Society for structural health monitoring of Intelligent Infrastrucure. All rights reserved.

关键词： Ground penetrating radar systems

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Reynolds number effects on mean aerodynamic forces acting on parallel cables of cable-supported bridges

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Gongcheng Lixue/Engineering Mechanics 2017年第3期34卷 189-196页

作者： Du, Xiao-Qing Zhang, Li-Ping Liu, Qing-Kuan Ma, Wen-Yong Liu, Xiao-Bing Department of Civil Engineering Shanghai University Shanghai200072 China Wind Engineering Research Center Shijiazhuang Tiedao University Shijiazhuang050043 China Hebei Province Key Lab of Structural Health Monitoring and Control Shijiazhuang050043 China

Parallel hanger cables and stay cables are used extensively in cable-supported bridges. However, the cross-wind mean lift of downstream cables induced by wake interference received little attention when calculating the wind loads on parallel cables. At Reynolds numbers between 0.9×105~4.6×105 (subcritical Reynolds regime and critical Reynolds regime), the aerodynamic characteristics of twin circular cylinders were investigated along with their relationships with the Reynolds numbers through a series of wind tunnel tests. Results show the mean aerodynamic forces of two circular cylinders in the critical regime were very different from those in the subcritical regime, showing strong Reynolds number effects. Furthermore, at the critical regime, the mean lift coefficients of the downstream circular cylinder discontinuously suffered abrupt change with the increase in the Reynolds number for some arrangements of the cylinders, which might be related to the shift of the flow state between different flow patterns. Under the wake interference of the upstream circular cylinder, the magnitude of the mean lift coefficient on the downstream cylinder was up to 1.25. Therefore, it is necessary to include the effect of mean lift when calculating static wind loads on parallel cables. © 2017, Engineering Mechanics Press. All right reserved.

关键词： Reynolds number

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The nature frequency identification of tunnel lining based on the microtremor method

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Underground Space 2016年第2期1卷 108-113页

作者： Yujing Jiang Yang Gao Xuezhen Wu Graduate School of Engineering Nagasaki UniversityNagasaki 852-8521Japan Key Laboratory of Structural Health Monitoring and Control Shijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology Shandong University of Science and TechnologyQingdao 266510China

Many tunnels all over the world have been in service for several decades,which require effective inspection methods to assess their health ***,as a type of ambient vibration originating from natural or artificial oscillations without specific sources,has attracted more and more attentions in the recent study of the microtremor dynamic properties of concrete *** this study,the microtremors of the tunnel lining were simulated numerically based on the Distinct Element Method(DEM).The Power Spectra Density(PSD)of signals obtained from numerical simulations were calculated and the nature frequencies were identified using the peak-picking *** influences of the rock-concrete joint,the rock type and the concrete type on the nature frequencies were also *** results of a comprehensive numerical analysis show that the nature frequencies lower than 100 Hz can be *** the bonding condition becomes worse,the nature frequencies *** nature frequencies change proportionally with the normal stiffness of the rock-concrete *** the concrete grade decreases,the third mode of frequency also decreases gradually while the variation of the first two modes of frequencies can hardly be ***,the field microtremor measurements of tunnel lining were also carried out to verify the numerical results.

关键词： Tunnel lining Frequency Vibration intensity Microtremor measurement Numerical simulation

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The influence of surface roughness on the dry galloping of inclined cables

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Gongcheng Lixue/Engineering Mechanics 2017年 34卷 174-178页

作者： Lu, Zhao-Liang Liu, Xiao-Ling Zheng, Yun-Fei Liu, Qing-Kuan Ma, Wen-Yong Liu, Xiao-Bing School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China Structural Health Monitoring and Control Institute Shijiazhuang Tiedao University Shijiazhuang050043 China Hebei Province Key Lab of Structural Health Monitoring and Control Shijiazhuang050043 China

Although new cables are covered by smooth polyethylene material, weathering and dust adhesion increase the surface roughness of the cables with the growth of service time. In this paper, the influence of roughness of stay cables on aerodynamic stability was studied. The surface roughness of cables was changed through covering the cable with different sandpapers, and the surface roughness was measured with the SJ-410 high-precision by free vibration wind tunnel test. The influence of surface roughness on the vibration of stay cables at high Reynolds number was studied by vibration experiments. It was shown that the vibration of stay cables was inhibited with the increase of the surface roughness;the Reynolds number effect became weaker with the increase of surface roughness of the stay cable models. © 2017, Engineering Mechanics Press. All right reserved.

关键词： Surface roughness

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