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Comparative Study on Structural Redundancy of Cable-Stayed and Extradosed Bridges Through Safety Assessment of Their Stay Cables

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Engineering 2021年第1期7卷 111-123页

作者： Khawaja Ali Hiroshi Katsuchi Hitoshi Yamada Department of Civil Engineering Yokohama National UniversityYokohama 240-8501Japan

This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use of inclined cables;however,the international standards for bridge design stipulate different safety factors for stay cables of both types of bridges.To address this misconception,a comparative study was carried out on the safety factors of stay cables under fatigue and ultimate limit states by considering the effects of various untoward and damaging factors,such as overloading,cable loss,and corrosion.The primary goal of this study is to describe the structural disparities between both types of bridges and evaluate their structural redundancies by employing deterministic and nondeterministic methods.To achieve this goal,three-dimensional finite-element models of both bridges were developed based on the current design guidelines for stay cables in Japan.After the balanced states of the bridge models were achieved,static analyses were performed for different safety factors of stay cables in a parametric manner.Finally,the first-order reliability method and Monte Carlo method were applied to determine the reliability index of stay cables.The analysis results show that cable-stayed and extradosed bridges exhibit different structural redundancies for different safety factors under the same loading conditions.Moreover,a significant increase in structural redundancy occurs with an incremental increase in the safety factors of stay cables.

关键词： Cable-stayed bridge Extradosed bridge Redundancy Stay cable Safety factor Reliability analysis

A wind tunnel study on control methods for cable dry-galloping

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Frontiers of Structural and Civil Engineering 2016年第1期10卷 72-80页

作者： Hung D. VO Hiroshi KATSUCHI Hitoshi YAMADA Mayuko NISHIO Department of Civil Engineering Yokohama National University Yokohama 240-8501 Japan

The common vibration of cable caused by rain-wind combination has been known as most typical type and a lot kind of its countermeasures has been proposed for suppressing this phenomenon. Recently, stayed-cables were also proved that they could be excited in dry state （without rain）, which is called dry-galloping. Recently, its mechanisms have been explained by axial flow, Reynolds number and so on. To clarify the characteristics of this galloping, wind tunnel test of a cable model with various kinds of wind angle was conducted. Then, three types of countermeasure were examined to suppress dry- galloping of bridge cable. The tests confirmed that the occurrence of dry-galloping depends on relative wind attacked angles and onset reduced wind speed. Furthermore, single spiral wire, double spiral wire and circular ring were found to have high effectiveness in mitigating this galloping when those are installed properly.

关键词： dry-galloping wind-relative angle single spiral wire double spiral wire circular rings

Improvement of aerodynamic stability of suspension bridges with H-shaped simplified stiffening girder

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Frontiers of Structural and Civil Engineering 2016年第1期10卷 93-102页

作者： Hiroshi KATSUCHI Hitoshi YAMADA Mayuko NISHIO Yoko OKAZAKI Department of Civil Engineering Yokohama National University Yokohama 240-8501 Japan

简化暂停桥 girder 结构的空气动力学的稳定性的改进上的风隧道学习与使用一个 1/40-scaled 节模型被进行。学习的目的是有 5001,000 m 中心跨度长度的一座经济地优异的暂停桥的发展。风隧道测试证明边系结类型十字节展出了大振幅扭力... 详细信息

简化暂停桥 girder 结构的空气动力学的稳定性的改进上的风隧道学习与使用一个 1/40-scaled 节模型被进行。学习的目的是有 5001,000 m 中心跨度长度的一座经济地优异的暂停桥的发展。风隧道测试证明边系结类型十字节展出了大振幅扭力的导致旋涡的颤动象一样扭力以低风速度拍翅。因此，开的栅栏甲板的空气动力学的反措施和三角形的 faring，和中心停留，斜 bracing 和集体增加的结构的反措施被试试改进空气动力学的稳定性。最后，到一座照原尺寸的桥的最好的联合的可行性被结构的分析检验。

关键词：空气动力稳定性悬索桥加劲梁气动稳定性 H型主梁结构扭转颤振风洞试验

Ionic Liquids in Energy and Environment

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Green Energy & Environment 2019年第2期4卷 93-94页

作者： Toshiyuki Itoh Masayoshi Watanabe Liangnian He Tottori university Yokohama National University Nankai university

Ionic liquids (ILs) have received a great deal of attention because they are less-volatile, less-flammable, have low toxicity and unique solubility for many organic and inorganic materials, and these properties allow them to be used in various fields of sustainable sciences. Remarkable progress in the science of ILs has been accomplished during the past two decades;the number of publications of ILs reached more than 90,000 since 1999 to be present [1]. ILs are nowwell recognized as essential players in the fields of environmental benign synthesis, catalysts, extraction, electrochemistry, and biotechnology, and they also attract much attention as a key technology to promote the spread of renewable energy.

关键词： ILs energy number

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

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Engineering 2017年第6期3卷 845-853页

作者： Hoang Trong Lam Hiroshi Katsuchi Hitoshi Yamada The university of Danang-university of Science and Technology Danang Vietnam Yokohama National University Yokohama 240-8501 Japan

本文介绍了在不同湍流条件下通过随机系统识别(SSI)方法提取颤振导数(FD)的过程。研究旨在通过对节段模型风洞试验来研究湍流对悬索式大跨度桥梁的影响。针对不同的湍流特性,对桁架式桥梁断面进行了几项风洞试验,包括降低湍流强度和湍... 详细信息

本文介绍了在不同湍流条件下通过随机系统识别(SSI)方法提取颤振导数(FD)的过程。研究旨在通过对节段模型风洞试验来研究湍流对悬索式大跨度桥梁的影响。针对不同的湍流特性,对桁架式桥梁断面进行了几项风洞试验,包括降低湍流强度和湍流尺度。研究包括湍流对模型动态响应的影响。利用系统识别技术提取FD,对风洞试验中的瞬态响应和抖振响应进行了分析,同时讨论了该方法存在的困难。利用时域SSI同时从一自由度(1DOF)和二自由度(2DOF)系统提取所有的FD。最后,讨论了不同情况下的结果并得出结论。

关键词：颤振导数系统识别湍流效应抖振响应

Seismic response reduction of a three-story building by an MR grease damper

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Frontiers of Mechanical Engineering 2017年第2期12卷 224-233页

作者： Tomoki SAKURAI Shin MORISHITA Graduate School of Environment and Information Sciences YokohamaNational University Yokohama 240-8501 Japan Environment and Information Sciences Yokohama National UniversityYokohama 240-8501 Japan

This paper describes an application of mag- neto-rheological （MR） grease dampers as seismic dampers for a three-story steel structure. MR fluid is widely known as a smart material with rheological properties that can be varied by magnetic field strength. This material has been applied to various types of devices, such as dampers, clutches, and engine mounts. However, the ferromagnetic particles dispersed in MR fluid settle out of the suspension after a certain interval because of the density difference between the particles and their carrier fluid. To overcome this defect, we developed a new type of controllable working fluid using grease as the carrier of magnetic particles. MR grease was introduced into a cylindrical damper, and the seismic performance of the damper was subsequently studied via numerical analysis. The analysis results of the MR grease damper were compared with those of other seismic dampers. We confirmed that the MR grease damper is an effective seismic damper.

关键词： MR grease damper seismic damper vibration control structural response FEM analysis

Wind-Tunnel Investigation of the Aerodynamic Performance of Surface-Modification Cables

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Engineering 2017年第6期3卷 817-822页

作者： Hiroshi Katsuchi Hitoshi Yamada Ippei Sakaki Eiichi Okado Yokohama National University Yokohama 240-8501 Japan Shinko Wire Company Ltd. Amagasaki 660-0091 Japan

学界对包括风雨激振(RWIV)和干索驰振(DG)在内的斜拉桥拉索的风致振动等的研究已经有相当长的时间。一般来说,我们会应用机械阻尼器或表面处理来抑制振动。特别是已开发出几种表面处理拉索,包括压痕、纵向平行突起、螺旋角和U形开槽。... 详细信息

学界对包括风雨激振(RWIV)和干索驰振(DG)在内的斜拉桥拉索的风致振动等的研究已经有相当长的时间。一般来说,我们会应用机械阻尼器或表面处理来抑制振动。特别是已开发出几种表面处理拉索,包括压痕、纵向平行突起、螺旋角和U形开槽。最近又开发了一种带螺旋突起的新型空气动力学稳定拉索,这种拉索已被证明具有与锯齿状拉索相似的低阻力系数,并且可以防止拉索表面形成水线。在本研究中,应用风洞实验对这种拉索在各种来流角度和突起尺寸下的RWIV稳定性进行了研究。发现对于所有测试风角,螺旋突起拉索对于RWIV和DG在空气动力学基础上都能保持稳定,突起尺寸的影响也得到了确认。

关键词：风雨激振干索驰振斜拉索风洞实验

The role of dilatancy in shallow overburden tunneling

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Underground Space 2019年第3期4卷 181-200页

作者： Muhammad Shehzad Khalid Mamoru Kikumoto Ying Cui Kiyoshi Kishid Department of Urban Management Kyoto UniversityNishikyo-KuKyoto 615-8540Japan Department of Civil Engineering Yokohama National UniversityYokohamaKanagawa 240-8501Japan

The mechanical behavior of sandy ground during shallow circular tunneling is explored for various overburden heights H(=0.5D,1.0D,1.5D and 2.0D;D is the diameter of the tunnel)and various dilatancy coefficients(w//=0,1/3,1/2,and 1;/and w are the internal friction angle and dilation angle,respectively)through finite difference analyses.The ground is modeled as a linear elastic-perfectly plastic material that employs the Mohr-Coulomb yield criterion and obeys the non-associated flow rule.The ground reaction curve is applied in conjunction with the stress path as a conceptual tool for interpreting the mechanical response of the ground to tunneling.It is revealed that,at a certain relaxation value,a yield zone develops during tunneling and extends to the surface.This relaxation value increases with increases in the overburden and w//values for the cases of less shallow tunnels(i.e.,H=1.0D,1.5D and 2.0D),while for the shallowest case(H=0.5D),the extent of the yield zone to the ground surface is not sensitive to the w//value.The shear strain due to tunneling also increases with an increase in the w//value.Moreover,the w//value affects the radial displacement and the surface settlement due to tunneling.The magnitudes of the surface settlement and the radial displacement at the tunnel crown both decrease with an increase in the w//value.The relative difference in the displacement at the tunnel crown between the upper bound and lower bound values,w//(at the last computed stage),increases with an increase in the overburden height.It is recommended,therefore,that careful consideration be given to the dilatancy angle in the case of relatively less shallow tunnels.

关键词： Shallow tunnels Dilatancy Overburden Ground reaction curve Stress path

THE M/PH/1 QUEUE WITH WORKING VACATIONS AND VACATION INTERRUPTION

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Journal of Systems Science and Systems Engineering 2010年第4期19卷 496-503页

作者： Yutaka BABA Faculty of Education and Human Sciences Yokohama National University

We study an M/PH/1 queue with phase type working vacation and vacation interruption where the vacation time follows a phase type distribution. The server serves the customers at a lower rate in a vacation period. The server comes back to the regular busy period at a service completion without completing the vacation. Such policy is called vacation interruption. In terms of quasi birth and death process and matrix-geometric solution method, we obtain the stationary queue length distribution. Moreover we obtain the conditional stochastic decomposition structures of queue length and waiting time when the service time distribution in the regular busy period is exponential.

关键词： Working vacation vacation interruption phase type distribution quasi birth and death process matrix-geometric solution stochastic decomposition