Abstract
The primary objective of this paper is to present the current capabilities for simulating atmospheric boundary layer
(ABL) flows in large-scale wind tunnels. The paper describes (i) methods for generating ABL flow conditions appropriate for
full- and large-scale experimental investigations, and (ii) the resulting flow characteristics obtained using these methods. The
Florida International University Wall of Wind Experimental Facility (WOW EF) and associated experimental and analytical
techniques used to simulate ABL flows are described. Resulting ABL flow simulations at various model scales are compared to
their Engineering Sciences Data Unit (ESDU) counterparts. Additionally, aerodynamic pressure measurements from WOW
models of the Wind Engineering Research Field Laboratory (WERFL) building at Texas Tech University (TTU) are compared
with full-scale field measurements recorded on the TTU prototype. The results of the comparisons, and uncertainties in the
simulated and field measured data are discussed, and suggestions are presented on future research needs.
Key Words
atmospheric boundary layer; full- and large-scale testing; partial turbulence simulation; wall of wind
Address
Dejiang Chen:International Hurricane Research Center, Florida International University, Miami, FL, USA
Arindam Chowdhury:1)International Hurricane Research Center, Florida International University, Miami, FL, USA
2)Department of Civil and Environmental Engineering, Florida International University, Miami, FL, USA
Ioannis Zisis:1)International Hurricane Research Center, Florida International University, Miami, FL, USA
2)Department of Civil and Environmental Engineering, Florida International University, Miami, FL, USA
Amal Elawady:1)International Hurricane Research Center, Florida International University, Miami, FL, USA
2)Department of Civil and Environmental Engineering, Florida International University, Miami, FL, USA
Abstract
Local instability is one of the most common forms of wind-induced failure of super-large cooling towers. Current
codes and research methods often neglect the coupling effect among the superstructure, pile, and soil, particularly during the
long-term construction process. This makes it challenging to accurately predict the wind resistance of such structures. Taking a
coastal super-large cooling tower as the research object, an integrated finite element model considering the whole construction
process and interaction among the superstructure, pile foundation, and soil was developed. The surface wind pressure on the
cooling tower was derived from wind tunnel rigid pressure measurement and the code K1.2 curve. Nonlinear stability analyses
under strong wind were performed for the structure-pile-soil coupling model and the base-fixed model. This study systematically
compared differences in the buckling coefficients and buckling displacements of the cooling tower during the whole
construction process, considering concrete age, construction loads, material and geometric nonlinearities, and internal suction
effect. The influence of structure-pile-soil interaction on the buckling stability of cooling towers was revealed, and an
engineering empirical formula was proposed to evaluate the relationship between buckling coefficients and construction
progress. The results indicate that considering structure-pile-soil interaction reduces the fundamental frequency of the super
large cooling tower by 18.78%, decreasing the local stability coefficient at the tower body, but increasing it at the tower top.
Considering concrete age, construction loads, and internal suction effect lead to reduced buckling stability of the cooling tower,
which is further weakened by the coupling effect. The most unfavorable condition for the buckling coefficient occurs when both
structure-pile-soil coupling and internal suction effect are considered simultaneously. Similarly, the most unfavorable condition
for buckling displacement occurs when pile-soil coupling, concrete age, and construction loads are jointly considered. The
proposed empirical formula demonstrates high reliability and stability, providing a scientific basis and practical reference for the
preliminary evaluation of the variation of buckling coefficients with construction conditions.
Key Words
structure-pile-soil interaction; super-large cooling tower, whole construction process; wind-induced nonlinear
stability
Address
Yifan Qi:1)Department of Civil and Airport Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
2)Key Laboratory of Civil Engineering Dynamic Multi-disaster Prevention, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
Shitang Ke:1)Department of Civil and Airport Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
2)Key Laboratory of Civil Engineering Dynamic Multi-disaster Prevention, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
Sainan Zen:1)Department of Civil and Airport Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
2)Key Laboratory of Civil Engineering Dynamic Multi-disaster Prevention, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
Yan Qin:1)Department of Civil and Airport Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
2)Key Laboratory of Civil Engineering Dynamic Multi-disaster Prevention, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
Wenjie Li:1)Department of Civil and Airport Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
2)Key Laboratory of Civil Engineering Dynamic Multi-disaster Prevention, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
Jiaqing Shu:China Energy Engineering Group Jiangsu Power Design Institute Co., LTD, Nanjing 211102, China
Abstract
The mountainous terrain is complex and the temperature changes greatly, which leads to the complex time and
spatial characteristics of the mountain wind field. The wind field shows obvious non-stationary characteristics. The standard
power spectrum only contains frequency domain information, which cannot accurately reflect the time-frequency domain
characteristics of mountain wind. It will be inaccurate to simulate mountain wind speed based on standard power spectrum, so it
is difficult to get accurate buffeting response of mountain bridge. In this paper, the wind speed is measured in mountainous
areas, and its non-stationary evolution power spectral density (EPSD) is obtained by Priestley method. Taking the measured
EPSD as the target, the fitting is conducted according to the model of time-varying PSD, so as to obtain the fitted EPSD of the
measured wind speed. The buffeting response of suspension bridge under mountain wind field is studied by simulating mountain
wind field with fitted EPSD. It is shown that the fitted time-varying power spectrum can better reflect the time-frequency
characteristics of measured wind speed. In addition, the fitted EPSD can simulate the measured wind speed more accurately.
Furthermore, the buffeting responses of suspension bridge with stationary, traditional non-stationary (modulation function) and
mountain non-stationary (modified EPSD) wind fields are analyzed. The response based on modified EPSD is the biggest,
which is 17% and 5% bigger than the stationary wind field and the traditional non-stationary wind field.
Key Words
buffeting response in mountains; measured wind speed characteristics; mountain area; time-varying
power spectral density
Address
Xinqi Zhang:School of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074, China
Jun Hu:1)School of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074, China
2)State Key Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing 400074, China
Yongyong Liang:School of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074, China
Fuming Yang:School of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074, China
Ao Shen:School of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074, China
Abstract
Tensile fabric structures are increasingly prevalent in civil engineering due to their aesthetic versatility and
lightweight nature; however, their susceptibility to aerodynamic instabilities poses significant challenges for safe and efficient
design. This study introduces an advanced computational framework that couples Computational Fluid Dynamics (CFD) with
Finite Element Analysis (FEA) to investigate the aeroelastic behavior of fabric structures under wind loading, offering a novel
approach to address these challenges. Through a meticulously validated fluid-structure interaction (FSI) methodology, the
framework employs vortex-induced vibration (VIV) simulations to confirm expected shedding frequencies and lock-in
phenomena, aligning closely with established literature trends. Applied to a pre-tensioned fabric panel, the methodology
identifies a critical pre-tension level that ensures structural stability at typical wind velocities, effectively mitigating dynamic
instabilities. At higher velocities, the panel exhibits pronounced vibrational modes, characterized by a transition from moving
waves to a standing wave pattern over time, driven by vortex shedding and flutter. As a foundational study, it underscores the
need for further research into advanced constitutive models, particularly those addressing viscoelastic properties and creep
behavior, to better simulate the long-term performance of fabric materials in real-world conditions, thus paving the way for safer
and more resilient structural designs.
Address
Mohammad Hosein Nejabatmeimandi:1)Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy
2)Tensys Ltd, 122 Wells Road, Bath, UK
Adrian Cabello:Tensys Ltd, 122 Wells Road, Bath, UK
Adam C. Bown :Tensys Ltd, 122 Wells Road, Bath, UK
Abstract
Wind loads on wind turbines situated on hilly terrains are substantially different than for wind turbines on flat
terrains. The terrain complexity may accordingly affect the fatigue load and service life of wind turbines. It is therefore the scope
of the present study to carefully assess aerodynamic characteristics of wind turbines in complex terrain. Wind-tunnel
experiments on small-scale models were designed and performed for this purpose. The horizontal-axis wind turbine model was
studied because it is the commonly used type of wind turbines in open terrains. The focus was on the size and shape of the hill
and the position of the wind turbine relative to the hill. In each case, a single wind-turbine model and a single hill model were
concurrently analyzed. The main parameters of interest are the thrust force and the bending moment of the wind-turbine model.
The results obtained indicate some important findings. The approach to wind-turbine modeling proved to be accurate and it is
recommended for future applications. The effects of hills on wind loads on a wind-turbine model proved to be substantial.
Created power is higher for wind turbines placed on a hill. Only twin and large hills channel airflow toward the blades, thus
increasing the power coefficient. Compared to the wind turbine with the same rotor hub height situated on the flat terrain, this
effect increases the power coefficient by 32% and the thrust force by 13%. The wind thrust force is larger on hilly terrains that
yields an increase in the rotor shaft bending and bearing loads, and shorter service life of wind turbines. This effect increases by
18% when the wind turbine is located on a large hill.
