Abstract
To evaluate the wind shielding effect of bridge towers with multiple limbs on high-speed trains, a wind tunnel test
was conducted to investigate the aerodynamic characteristics of vehicles traversing multi-limb towers, which represented a
combination of the steady aerodynamic coefficient of the vehicle-bridge system and wind environment around the tower.
Subsequently, the analysis model of wind-vehicle-bridge (WVB) system considering the additional moments caused by lift and
drag forces under nonuniform wind was proposed, and the reliability and accuracy of the proposed model of WVB system were
verified using another model. Finally, the factors influencing the wind shielding effect of multi-limb towers were analyzed. The
results indicate that the wind speed distributions along the span exhibit two sudden changes, and the wind speed generally
decreases with increasing wind direction angle. The pitching and yawing accelerations of vehicles under nonuniform wind loads
significantly increase due to the additional pitching and yawing moments. The sudden change values of the lateral and yawing
accelerations caused by the wind shielding effect of multi-limb tower are 0.43 m/s2 and 0.11 rad/s2 within 0.4 s, respectively.
The results indicate that the wind shielding effect of a multi-limb tower is the controlling factor in WVB systems.
Key Words
multi-limb tower; nonuniform wind; running safety; wind-vehicle-bridge (WVB) system; wind shielding effect;
wind tunnel test
Address
Xu Han:1)Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China
2)Chengdu Engineering Limited Liability Company of China Railway No. 5 Engineering Group Co., Ltd., Chengdu 610031, Sichuan, China
Huoyue Xiang and Yongle Li:1)1Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China 2)3Wind Engineering Key Laboratory of Sichuan Province, Chengdu 610031, Sichuan, China
Xuli Chen:Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China
Abstract
To better estimate the non-Gaussian extreme wind pressures for high-rise buildings, a data-driven revised Hermitetype peak factor estimation model is proposed in this papar. Subsequently, a comparative study on three types of methods, such
as Hermite-type models, short-time estimate Gumbel method (STE), and new translated-peak-process method (TPP) is carried
out. The investigations show that the proposed Hermite-type peak factor has better accuracy and applicability than the other
Hermite-type models, and its absolute accuracy is slightly inferior to the STE and new TPP methods for non-Gaussian wind
pressures by comparing with the observed values. Moreover, these methods generally overestimate the Gaussian wind pressures
especially the STE.
Address
Dongmei Huang:1)School of Civil Engineering, Central South University, Changsha, Hunan 410075, China
2)National Engineering Research Center of High-speed Railway Construction Technology, Central South University, Changsha, Hunan 410075, China
Hongling Xie:School of Civil Engineering, Central South University, Changsha, Hunan 410075, China
Qiusheng Li:Department of Architecture and Civil Engineering, City University of Hong Kong, Kowloon, Hong Kong
Abstract
This paper investigates the mechanical behavior of full-scale offshore fish cages under hydrodynamic loads. To
simulate different cases, different materials were used in the fish cage and analyzed under different flow velocities. The cage
system is studied in two parts: net cage and floating collar. Analyses were performed with the ANSYS Workbench program,
which allows the Finite Element Method (FEM) and Computational Fluid Dynamics (CFD) method to be used together. Firstly,
the fish cage was designed, and adjusted for FSI: Fluid (Fluent) analysis. Secondly, mesh structures were created, and
hydrodynamic loads acting on the cage elements were calculated. Finally, the hydrodynamic loads were transferred to the
mechanical model and applied as a pressure on the geometry. In this study, the equivalent (von Mises) stress, equivalent strain,
and total deformation values of cage elements under hydrodynamic loads were investigated. The data obtained from the analyses
were presented as figures and tables. As a result, it has been shown that it is appropriate to use all the materials examined for the
net cage and the floating collar.
Key Words
cage systems; computational fluid dynamics; finite element method
Address
Mehmet Emin Özdemir:Department of Civil Engineering, Cankiri Karatekin University, 18100, Çankiri, Trukey
Murat Yaylac:Department of Civil Engineering, Recep Tayyip Erdogan University, 53100, Rize, Turkey
Abstract
The effect of cladding panel size on the size reduction factor (SRF) of extreme area-averaging wind pressure
(EAWP) on the facades of a high-rise building is often ignored in previous studies. Based on wind tunnel tests, this study
investigated the horizontal and vertical correlations of wind pressure on the facade claddings of square-section high-rise
buildings. Then, the influencing parameters on the SRF of the EAWP on the cladding panels were analyzed, which were the
panel area, panel width, panel length and building width. The results show clear regional distinctions in the correlation of wind
pressures on the building facades and the rules of the horizontal and vertical correlations are remarkably different, which causes
the cladding size ratio to impact the SRF significantly. Therefore, this study suggests the use of the non-dimensional
comprehensive size parameter 𝒃
𝛂𝒉
𝟏−𝛂/𝑩 (𝜶 is the fitting parameter) determined by the cladding panel horizontal size b,
cladding panel vertical size h and the building width B rather than the cladding panel area to describe the variation of the EAWP.
Finally, some empirical formula for the SRF of the EAWP on the cladding of a high-rise building is proposed with the nondimensional comprehensive size parameter.
Key Words
area-averaging wind pressure; cladding; high-rise building; size reduction factor; spatial correlation coefficient;
wind tunnel test
Address
Xiang Wang, Yong Quan and Ming Gu:State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092
Zhengwei Zhang:1)Jiangsu College of Engineering and Technology, Nantong 226006
2)Arup International Consultants (Shanghai) Co. Ltd., Shanghai 200031, China
Abstract
In this article, a novel structural modal parameters identification methodology is developed to determine the natural
frequencies and damping ratios of civil structures based on the symplectic geometry mode decomposition (SGMD) approach.
The SGMD approach is a new decomposition algorithm that can decompose the complex response signals with better
decomposition performance and robustness. The novel method firstly decomposes the measured structural vibration response
signals into individual mode components using the SGMD approach. The natural excitation technique (NExT) method is then
used to obtain the free vibration response of each individual mode component. Finally, modal natural frequencies and damping
ratios are identified using the direct interpolating (DI) method and a curve fitting function. The effectiveness of the proposed
method is demonstrated based on numerical simulation and field measurement. The structural modal parameters are identified
utilizing the simulated non-stationary responses of a frame structure and the field measured non-stationary responses of a supertall building during a typhoon. The results demonstrate that the developed method can identify the natural frequencies and
damping ratios of civil structures efficiently and accurately.
Key Words
civil structure; modal parameter identification; non-stationary response; Symplectic Geometry Model
Decomposition
Address
Feng Hu, Lunhai Zhi, Zhixiang Hu:College of Civil Engineering, Hefei University of Technology, Hefei 230009, China
Bo Chen:Key Laboratory of Roadway Bridge and Structural Engineering, Wuhan University of Technology, Wuhan 430070, China
