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(searched for: doi:10.1080/15732479.2019.1625416)
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Sunjoong Kim, , Ho-Kyung Kim
Published: 12 January 2022
Journal of Sound and Vibration, Volume 524; https://doi.org/10.1016/j.jsv.2022.116758

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Han Zhang, , Zidong Xu, Yiming Zhang, Tianyou Tao, Jianxiao Mao
Journal of Wind Engineering and Industrial Aerodynamics, Volume 221; https://doi.org/10.1016/j.jweia.2021.104883

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Chao Yang, Zhengqing Chen, , ,
Journal of Engineering Mechanics, Volume 148; https://doi.org/10.1061/(asce)em.1943-7889.0002053

Abstract:
Design of external dampers for stay cables requires repetitive evaluation of damping ratios for target modes of cables under various damper parameters and installation positions, and explicit formulas with high accuracy to estimate the modal-damping ratios for a cable-damper system are helpful in designing external dampers. This study deals with the evaluation of the modal damping of cables with an external viscous damper close to the anchorage. A considerably accurate and explicit formula for calculating the modal-damping ratios of the cable-damper system is derived by evaluating the imaginary and real part of the complex frequency equation. It is demonstrated that the formula is able to predict the modal-damping ratios of the cable-damper system both for lower and higher modes. Based on the proposed formula, the effects of the modal order and installation position on the modal-damping ratio of the cable-damper system are studied. A closed-form solution for the optimal damping coefficient is proposed and the maximum attainable modal damping is also obtained.
, Mehmet Akköse
Structure and Infrastructure Engineering pp 1-20; https://doi.org/10.1080/15732479.2021.1952437

Abstract:
Cable-stayed bridges have been constructed with different type of towers (pylons) in the World, namely H-shaped, A-shaped, inverted Y-shaped, single column, diamond-shaped. More than half of the cable-stayed bridges utilised the towers with inclined legs. The dynamic response of inclined tower legs can be extremely complicated during earthquakes. Real earthquakes provide an excellent opportunity to gain insight into the performance of the towers. The present paper focuses on the real dynamic responses of inverted Y-shaped towers in long span cable-stayed bridges by using monitoring data recorded during moderate earthquakes. Nissibi cable-stayed bridge with two inverted Y-shaped towers constructed in Adıyaman, Turkey is selected for the application. Samsat (Adıyaman) earthquake with magnitude 5.5 (Mw) occurred near the bridge site. The dynamic responses of the bridge towers during the earthquake have been recorded using 3 D accelerometers. Vertical and horizontal spatial variations of the acceleration responses recorded during the earthquake at the foundation, deck and top levels of the two towers in longitudinal, transverse and vertical directions are evaluated and compared with each other. Significantly acceleration amplifications along the height of the towers and arrival time delays between the tower foundations are observed on the selected cable-stayed bridge.
Published: 23 May 2021
Engineering Structures, Volume 242; https://doi.org/10.1016/j.engstruct.2021.112495

Abstract:
Dampers are widely used for mitigating cable vibrations, particularly for rain-wind vibrations which often occur in low-frequency modes with large vibration amplitudes. However, it has been observed in existing bridges that a long cable attached with a damper still experiences vortex-induced vibrations in high-frequency modes with a mode shape having a node close to the position of the damper. Therefore, this study proposes to add a device to suppress such high-mode cable vibrations. Three typical dampers are respectively considered as the additional device, i.e., a viscous damper (VD), a high-damping rubber (HDR) damper and a tuned mass damper (TMD). A theoretical model of a shallow cable under two transverse forces at different locations is applied for dynamic analysis. Multimode damping of a cable equipped with two dampers is investigated based on numerical solution of the system frequency equation, and maximal high-mode damping is pursued by optimizing parameters of the dampers on the cable consecutively and simultaneously. Results show that the three types of dampers can all improve damping of the cable modes vulnerable to vortex-induced vibrations. When an additional VD is installed between the original VD and the closer cable end, a decrease in the viscous coefficient of the original damper can improve damping of the higher-order modes. When an HDR damper is installed on the cable between the VD and the nearer anchorage, damping in more low modes is decreased as compared to the case when a VD is installed because of the stiffness of the HDR damper. The HDR damper mainly induces a change in the mode shape of high cable modes and hence the original damper can dissipate more vibration energy. In the case of adding a TMD, no adverse effect on cable damping is found in all the modes. Finally, the procedure for designing two dampers to control both low-mode and high-mode cable vibrations is provided.
Runchuan Xia, , Jianting Zhou, Leng Liao, Wenqi Yang, Ya Li
Nondestructive Testing and Evaluation, Volume 37, pp 56-70; https://doi.org/10.1080/10589759.2021.1900846

Abstract:
The metal magnetic memory is used to detect the micro damage of structure based on the SMFL (self-magnetic flux leakage) effect, but it lacks an effective comprehensive diagnosis index suitable for the ferromagnetic material. In this paper, steel strand specimens were tensioned at different force levels, and the experimental study on the corrosion detection was carried out. Besides the monitoring analysis of the cable force, the initial structural magnetic field ΔBx0 and the surface SMFL signals Bx(α) induced by corrosion were both analysed. The results show that ΔBx0 curves of steel strand material present the periodic fluctuation. Considering ΔBx0 and measuring distance z, the proposed dimensionless damage analysis index X can be used for the quantitative research of corrosion diagnosis. The small influence of the cable force on index X is also illustrated. Moreover, the strong correlation that exists between the average maximum index Xmax and the corrosion ratio α is well fitted by the three-order polynomial curves.
, Jingsi Shen, Shuqiong Li, Zhengqing Chen, Qingbao Ou, Dabo Xin
Published: 3 December 2020
Journal of Fluids and Structures, Volume 100; https://doi.org/10.1016/j.jfluidstructs.2020.103195

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