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Extreme wind events (e.g., thunderstorm downbursts) often present strong nonstationarities in terms of time-varying mean, amplitude modulation and frequency modulation. The stationary-wind assumption adopted in the traditional analysis framework for wind-induced structural responses may lead to severely biased estimates in nonstationary scenarios. Accordingly, advanced methodologies have recently emerged to investigate nonstationary wind effects on structures. Since the consideration of nonstationary winds and associated structural aerodynamics and dynamics usually involves more time and effort in comparison of stationary case, it is important to first measure the degree of nonstationarity of wind signals for selecting an appropriate analysis framework (stationary or nonstationary). In this study, a Hilbert-wavelet-based nonstationarity index is developed to quantify the nonstationarity of extreme winds. The joint utilization of Hilbert transform and wavelet packet decomposition provides a sharp time-frequency representation of the analyzed signal, and hence lays a solid foundation for the nonstationarity quantification. To highlight that the same wind nonstationarity may present different contributions to dynamic responses of various structures, the structural aerodynamics and dynamics are integrated into the proposed nonstationarity index to form a multi-level quantification framework. Furthermore, the obtained Hilbert-wavelet-based multi-level nonstationarity index of a nonstationary wind signal is first summarized over the time and frequency domains and then normalized by the corresponding nonstationarity index of an impulse signal (treated as the most nonstationary signal) for convenient application and easy interpretation of the quantification results. The effectiveness of the proposed index for multi-level quantification of nonstationarity is well demonstrated with its applications to synthesized signals as well as field-measured downburst winds.
Haifeng Wang; Teng Wu. A Hilbert-wavelet-based nonstationarity index for multi-level quantification of extreme winds. Journal of Wind Engineering and Industrial Aerodynamics 2021, 215, 104682 .
AMA StyleHaifeng Wang, Teng Wu. A Hilbert-wavelet-based nonstationarity index for multi-level quantification of extreme winds. Journal of Wind Engineering and Industrial Aerodynamics. 2021; 215 ():104682.
Chicago/Turabian StyleHaifeng Wang; Teng Wu. 2021. "A Hilbert-wavelet-based nonstationarity index for multi-level quantification of extreme winds." Journal of Wind Engineering and Industrial Aerodynamics 215, no. : 104682.
Structural shape optimization plays an important role in the design of wind‐sensitive structures. The numerical evaluation of aerodynamic performance for each shape search and update during the optimization process typically involves significant computational costs. Accordingly, an effective shape optimization algorithm is needed. In this study, the reinforcement learning (RL) method with deep neural network (DNN)‐based policy is utilized for the first time as a shape optimization scheme for aerodynamic mitigation of wind‐sensitive structures. In addition, “tacit” domain knowledge is leveraged to enhance the training efficiency. Both the specific direct‐domain knowledge and general cross‐domain knowledge are incorporated into the deep RL‐based aerodynamic shape optimizer via the transfer‐learning and meta‐learning techniques, respectively, to reduce the required datasets for learning an effective RL policy. Numerical examples for aerodynamic shape optimization of a tall building are used to demonstrate that the proposed knowledge‐enhanced deep RL‐based shape optimizer outperforms both gradient‐based and gradient‐free optimization algorithms.
Shaopeng Li; Reda Snaiki; Teng Wu. A knowledge‐enhanced deep reinforcement learning‐based shape optimizer for aerodynamic mitigation of wind‐sensitive structures. Computer-Aided Civil and Infrastructure Engineering 2021, 1 .
AMA StyleShaopeng Li, Reda Snaiki, Teng Wu. A knowledge‐enhanced deep reinforcement learning‐based shape optimizer for aerodynamic mitigation of wind‐sensitive structures. Computer-Aided Civil and Infrastructure Engineering. 2021; ():1.
Chicago/Turabian StyleShaopeng Li; Reda Snaiki; Teng Wu. 2021. "A knowledge‐enhanced deep reinforcement learning‐based shape optimizer for aerodynamic mitigation of wind‐sensitive structures." Computer-Aided Civil and Infrastructure Engineering , no. : 1.
The frequency content and spatial correlation of nonstationary wind fields during extreme events typically present time-variant characteristics. Several effective schemes [e.g., using evolutionary power spectral density (EPSD) or Hilbert spectrum] have been highly developed and extensively used for analysis and the synthesis of time-dependent frequency distributions, whereas, until very recently, little attention has been paid to the accurate and efficient simulation of time-varying spatial correlations. The Hilbert transform together with the wavelet technique (Hilbert–wavelet scheme) holds great promise in accomplishing this task since a nonlinear, statistical relationship between the instantaneous phase difference and time-variant spatial correlation has recently been established. However, its engineering application is limited by the need to simultaneously solve a large number of nonlinear equations. To address this issue, the simultaneous matrix diagonalization (SMD) technique is introduced here to accelerate the Hilbert–wavelet simulation of nonstationary wind fields. Specifically, the SMD effectively obtains the target spatial correlation by the linear combination of uncorrelated wavelet subcomponents of the multivariate wind process. In addition, memory usage in the simulation of time-variant spatial correlation is greatly reduced using SMD. The SMD technique is usually implemented with iterative algorithms. To further improve the simulation efficiency, two-dimensional singular value decomposition (2dSVD) is employed to achieve a noniterative SMD. The high simulation fidelity and efficiency of the proposed Hilbert-wavelet-SMD approach are demonstrated by numerical examples. The simulation time consumption is compared with the state-of-the-art EPSD-based approach, and the proposed Hilbert-wavelet-SMD scheme shows superior efficiency.
Haifeng Wang; Teng Wu. Fast Hilbert–Wavelet Simulation of Nonstationary Wind Field Using Noniterative Simultaneous Matrix Diagonalization. Journal of Engineering Mechanics 2021, 147, 04020153 .
AMA StyleHaifeng Wang, Teng Wu. Fast Hilbert–Wavelet Simulation of Nonstationary Wind Field Using Noniterative Simultaneous Matrix Diagonalization. Journal of Engineering Mechanics. 2021; 147 (3):04020153.
Chicago/Turabian StyleHaifeng Wang; Teng Wu. 2021. "Fast Hilbert–Wavelet Simulation of Nonstationary Wind Field Using Noniterative Simultaneous Matrix Diagonalization." Journal of Engineering Mechanics 147, no. 3: 04020153.
Surface wind and rain fields are two significant elements of hurricane-induced hazards in coastal areas. Mitigation of losses due to hurricane wind and rain hazards has become an increasing urgent and challenging issue in light of changing climate and continued escalation of coastal population density, prompting the need for a more advanced risk analysis methodology to take global warming effects into consideration. In this study, the assessment of hurricane surface wind and rain hazards under changing climate is achieved by performing three simulation components, namely an enhanced hurricane track model to generate the synthesized storms (including a physics-based intensity model integrating sea surface temperature (SST), wind shear, and convective instability contributions), a newly developed thermal wind balance-based model to simulate the gradient wind profiles (explicitly considering environmental conditions of SST, temperature at the top of atmospheric boundary layer, and outflow temperature), and a height-resolving boundary-layer model to obtain the surface wind and rain fields (reducing inherent uncertainties associated with conventionally used gradient-to-surface wind speed conversion factors). A total of 10,000 years of hurricane events are generated for both observed (historical) and projected climate conditions, and a systematical comparison between these two scenarios is investigated. The simulation and comparison results highlight the important effects of a global warming scenario on hurricane surface wind and rain fields, and hence on critical civil infrastructure in hurricane-prone areas.
Reda Snaiki; Teng Wu. Hurricane Hazard Assessment Along the United States Northeastern Coast: Surface Wind and Rain Fields Under Changing Climate. Frontiers in Built Environment 2020, 6, 1 .
AMA StyleReda Snaiki, Teng Wu. Hurricane Hazard Assessment Along the United States Northeastern Coast: Surface Wind and Rain Fields Under Changing Climate. Frontiers in Built Environment. 2020; 6 ():1.
Chicago/Turabian StyleReda Snaiki; Teng Wu. 2020. "Hurricane Hazard Assessment Along the United States Northeastern Coast: Surface Wind and Rain Fields Under Changing Climate." Frontiers in Built Environment 6, no. : 1.
Hurricane wind risk assessment has been significantly improved with the evolvement of synthesis methodologies from the single site probabilistic method to the hurricane track model (including five simulation components of genesis, translation, intensity, decay and boundary-layer wind). As first-step efforts towards advancing the data-driven hurricane track model, widely used by engineering community, to a physics-based framework for more accurate and reliable hurricane risk assessment, a new intensity model integrating important dynamics and thermodynamics inside the storms is developed. Furthermore, an extensive statistical analysis of hurricane trajectories is carried out to obtain an enhanced translation model and a height-resolving analytical wind model is utilized to acquire the vertical profiles of wind speed and direction between ground-surface and gradient levels. The other two simulation components (i.e., genesis and decay) of the hurricane track model are also revisited for the sake of completeness. Ten thousand years of full-track synthetic hurricanes are generated and compared with the HURDAT database at specific mileposts along the US East coast to validate the overall performance of the developed simulation framework (in terms of annual occurrence rate, intensity, translation speed and heading angle). Then, the New Jersey coastline is employed as a case study to compare the simulated hurricane wind speeds with ASCE 7–16 recommendations, to highlight the wind directionality effects on extreme wind speeds, and to investigate the joint distribution of hurricane wind speed and size.
Reda Snaiki; Teng Wu. Revisiting hurricane track model for wind risk assessment. Structural Safety 2020, 87, 102003 .
AMA StyleReda Snaiki, Teng Wu. Revisiting hurricane track model for wind risk assessment. Structural Safety. 2020; 87 ():102003.
Chicago/Turabian StyleReda Snaiki; Teng Wu. 2020. "Revisiting hurricane track model for wind risk assessment." Structural Safety 87, no. : 102003.
A framework was proposed to identify a comprehensive set of aerodynamic admittance functions for bridge decks. The contributions of the cross-spectra between longitudinal and vertical wind velocity components and between turbulence components and gust-induced forces were embedded in the identification procedure. To facilitate application of the identified functions in engineering practice, the concept of an equivalent aerodynamic admittance function was introduced and numerically validated. The equivalent aerodynamic admittance functions of a set of streamlined and bluff cross sections were identified experimentally in a wind tunnel. Buffeting analysis of a bridge deck was carried out and the response predicted using the identified aerodynamic admittance functions compared well with the measured response. In addition, a sensitivity analysis was performed to delineate the influence of aerodynamic and structural parameters on the buffeting response, thereby demonstrating the significance of the proposed identification framework.
Lin Zhao; Xi Xie; Teng Wu; Shao-Peng Li; Zhi-Peng Li; Yao-Jun Ge; Ahsan Kareem. Revisiting aerodynamic admittance functions of bridge decks. Journal of Zhejiang University-SCIENCE A 2020, 21, 535 -552.
AMA StyleLin Zhao, Xi Xie, Teng Wu, Shao-Peng Li, Zhi-Peng Li, Yao-Jun Ge, Ahsan Kareem. Revisiting aerodynamic admittance functions of bridge decks. Journal of Zhejiang University-SCIENCE A. 2020; 21 (7):535-552.
Chicago/Turabian StyleLin Zhao; Xi Xie; Teng Wu; Shao-Peng Li; Zhi-Peng Li; Yao-Jun Ge; Ahsan Kareem. 2020. "Revisiting aerodynamic admittance functions of bridge decks." Journal of Zhejiang University-SCIENCE A 21, no. 7: 535-552.
The supergradient winds that may have severe implications on the wind design of high-rise buildings have been commonly observed in the hurricane boundary layer. However, the widely-used log-law or power-law wind profile excludes the supergradient-wind region in which the tangential winds are larger than the gradient winds. Although high-fidelity, nonlinear hurricane wind models may well capture the supergradient winds, high computational demand is needed for each simulation. Recently developed linear, height-resolving hurricane wind models, while can efficiently consider the existence of supergradient winds, significantly underestimate them due essentially to the ignorance of vertical advection term in the governing equations. A number of studies have actually demonstrated that the vertical advection is a major contributor to the transfer of horizontal momentum to the supergradient region. To this end, a refined analytical model that simultaneously integrates the horizontal advection, vertical advection and vertical diffusion terms into the governing equations is developed for accurately and efficiently estimating the hurricane supergradient winds. The important role of the vertical wind speed in determining the horizontal wind speeds (including supergradient winds) in the hurricane boundary layer is highlighted. Since the horizontal and vertical wind components are mutually dependent, the iteration technique is utilized to solve the proposed analytical model. The consideration of the vertical advection results in intensified supergradient winds that are consistent with the observations. Furthermore, a strong outflow region in the vicinity of the radius of maximum winds due to the supergradient winds can be obtained. Due to its simplicity and computational efficiency, the developed analytical model can be easily implemented in the Monte Carlo simulations for the rapid assessment of hurricane wind risk to coastal structures, especially to high-rise buildings.
Reda Snaiki; Teng Wu. An analytical model for rapid estimation of hurricane supergradient winds. Journal of Wind Engineering and Industrial Aerodynamics 2020, 201, 104175 .
AMA StyleReda Snaiki, Teng Wu. An analytical model for rapid estimation of hurricane supergradient winds. Journal of Wind Engineering and Industrial Aerodynamics. 2020; 201 ():104175.
Chicago/Turabian StyleReda Snaiki; Teng Wu. 2020. "An analytical model for rapid estimation of hurricane supergradient winds." Journal of Wind Engineering and Industrial Aerodynamics 201, no. : 104175.
This study carries out a detailed full-scale investigation on the strong wind characteristics at a cable-stayed bridge site and associated buffeting response of the bridge structure during construction, using a field monitoring system. It is found that the wind turbulence parameters during the typhoon and monsoon conditions share a considerable amount of similarity, and they can be described as the input turbulence parameters for the current wind-induced vibration theory. While the longitudinal turbulence integral scales are consistent with those in regional structural codes, the turbulence intensities and gust factors are less than the recommended values. The wind spectra obtained via the field measurements can be well approximated by the von Karman spectra. For the buffeting response of the bridge under strong winds, its vertical acceleration responses at the extreme single-cantilever state are significantly larger than those in the horizontal direction and the increasing tendencies with mean wind velocities are also different from each other. The identified frequencies of the bridge are utilized to validate its finite element model (FEM), and these field-measurement acceleration results are compared with those from the FEM-based numerical buffeting analysis with measured turbulence parameters.
Lei Yan; Lei Ren; Xuhui He; Siying Lu; Hui Guo; Teng Wu. Strong Wind Characteristics and Buffeting Response of a Cable-Stayed Bridge under Construction. Sensors 2020, 20, 1228 .
AMA StyleLei Yan, Lei Ren, Xuhui He, Siying Lu, Hui Guo, Teng Wu. Strong Wind Characteristics and Buffeting Response of a Cable-Stayed Bridge under Construction. Sensors. 2020; 20 (4):1228.
Chicago/Turabian StyleLei Yan; Lei Ren; Xuhui He; Siying Lu; Hui Guo; Teng Wu. 2020. "Strong Wind Characteristics and Buffeting Response of a Cable-Stayed Bridge under Construction." Sensors 20, no. 4: 1228.
Rapid increase in the bridge spans and the attendant innovative bridge deck cross-sections have placed significant importance on effectively modeling of the nonlinear, unsteady bridge aerodynamics. To this end, the deep long short-term memory (LSTM) networks are utilized in this study to develop a reduced-order model of the wind-bridge interaction system, where the model inputs are bridge deck motions and model outputs are motion-induced aerodynamics forces. The deep LSTM networks are first trained using the high-fidelity input-output aerodynamics datasets (e.g., based on the full-order computational fluid dynamics simulations). With the trained LSTM networks, it has been demonstrated that the bridge motion-induced nonlinear unsteady aerodynamics forces can be accurately and efficiently predicted. Numerical examples involving both the linear and nonlinear aerodynamics are employed to explore the flutter and post-flutter behaviors of bridges with the reduced-order model based on deep LSTM networks.
Tao Li; Teng Wu; Zhao Liu. Nonlinear unsteady bridge aerodynamics: Reduced-order modeling based on deep LSTM networks. Journal of Wind Engineering and Industrial Aerodynamics 2020, 198, 104116 .
AMA StyleTao Li, Teng Wu, Zhao Liu. Nonlinear unsteady bridge aerodynamics: Reduced-order modeling based on deep LSTM networks. Journal of Wind Engineering and Industrial Aerodynamics. 2020; 198 ():104116.
Chicago/Turabian StyleTao Li; Teng Wu; Zhao Liu. 2020. "Nonlinear unsteady bridge aerodynamics: Reduced-order modeling based on deep LSTM networks." Journal of Wind Engineering and Industrial Aerodynamics 198, no. : 104116.
The consideration of train-bridge system under winds has been attracted extensive attentions, but the winds are typically treated as stationary. This stationary assumption clearly presents a departure from the field observations during extreme storms (e.g., tropical cyclones, thunderstorms and tornadoes). The assurance of structural safety and reliability requires accurate modeling of the non-stationary features in the coupled high-speed train-bridge vibration system. In this study, an efficient analysis framework for high-speed train-bridge coupled vibrations under non-stationary winds based on the pseudo excitation method (PEM) has been developed, in which the non-stationary winds were transformed into a series of pseudoharmonic excitation vectors. The high simulation fidelity and computational efficiency of the established analysis framework were verified based on a case study where the train run over a seven-span continuous girder high-speed railway bridge. A number of transient durations and maximum wind speeds associated with various extreme events are investigated to comprehensively examine the non-stationary effects on the high-speed train-bridge coupled vibrations. It has been demonstrated that the non-stationary characteristics of winds presented important contributions to the dynamic performance of the coupled train-bridge interaction system.
Xu-Hui He; Kang Shi; Teng Wu. An efficient analysis framework for high-speed train-bridge coupled vibration under non-stationary winds. Structure and Infrastructure Engineering 2019, 16, 1326 -1346.
AMA StyleXu-Hui He, Kang Shi, Teng Wu. An efficient analysis framework for high-speed train-bridge coupled vibration under non-stationary winds. Structure and Infrastructure Engineering. 2019; 16 (9):1326-1346.
Chicago/Turabian StyleXu-Hui He; Kang Shi; Teng Wu. 2019. "An efficient analysis framework for high-speed train-bridge coupled vibration under non-stationary winds." Structure and Infrastructure Engineering 16, no. 9: 1326-1346.
Wind characteristics (e.g., mean wind speed, gust factor, turbulence intensity and integral scale, etc.) are quite scattered in different measurement conditions, especially during typhoon and/or hurricane processes, which results in the structural engineer ambiguously determining the wind parameters in wind-resistant design of buildings and structures in cyclone-prone regions. In tropical cyclones (including typhoons and hurricanes), the inconsistent wind characteristics may be in part ascribed to the complex flow structure with the coexistence of both mechanical and convective turbulence in the boundary layer of tropical cyclones. Another significant contribution to the scattered wind characteristics is due to various measurement conditions (e.g., terrain exposure and height) and data processing schemes (e.g., averaging time). The removal of the inconsistency in the field-measurement system may offer a more rational comparison of measured wind data from various observation platforms, and hence facilitates a better identification scheme of the wind characteristics to guide the urban planning design and wind-resistant design of buildings and structures. In this study, an analytical framework was firstly proposed to eliminate the potential observation-related effects in wind characteristics and then the wind characteristics of seven field measured tropical cyclones (four typhoons and three hurricanes) were comparatively investigated. Specifically, field measurements of wind characteristics were converted to a standard reference station with a roughness length of 0.03 m, observation duration of 10 min for mean wind and averaging time of 3 s for gusty wind at a 10 m height. The differences of the measured wind characteristics between the typhoons and hurricanes were highlighted. The standardized turbulent wind characteristics under the analytical framework for typhoons and hurricanes were compared with the corresponding recommendations in standard of American Society of Civil Engineers (ASCE 7-10) and Architectural Institute of Japan Recommendations for Loads on Buildings (AIJ-RLB-2004).
Lixiao Li; Yizhuo Zhou; Haifeng Wang; Haijun Zhou; Xuhui He; And Teng Wu; Zhou. An Analytical Framework for the Investigation of Tropical Cyclone Wind Characteristics over Different Measurement Conditions. Applied Sciences 2019, 9, 5385 .
AMA StyleLixiao Li, Yizhuo Zhou, Haifeng Wang, Haijun Zhou, Xuhui He, And Teng Wu, Zhou. An Analytical Framework for the Investigation of Tropical Cyclone Wind Characteristics over Different Measurement Conditions. Applied Sciences. 2019; 9 (24):5385.
Chicago/Turabian StyleLixiao Li; Yizhuo Zhou; Haifeng Wang; Haijun Zhou; Xuhui He; And Teng Wu; Zhou. 2019. "An Analytical Framework for the Investigation of Tropical Cyclone Wind Characteristics over Different Measurement Conditions." Applied Sciences 9, no. 24: 5385.
A describing function (DF)-based model is introduced for the simulation of vortex-induced vibration (VIV) of bridge decks. Similar to the linear frequency response function, the DF is the complex ratio of the first-order component of the nonlinear output to the harmonic input. The DF can be either identified using the forced vibration technique or based on the VIV nonlinear response time history. An iterative procedure is accordingly developed to predict the VIV response with the DF-based model, and an equivalent-damping-ratio-based simplified method is further proposed to efficiently obtain the limit cycle oscillation (LCO) amplitude of VIV. It is demonstrated that the conventional van der Pol-type model is equivalent to a special case of the DF-based model for VIV. Three case studies involving various cross-sections are utilized to validate the simulation accuracy and efficiency of the proposed DF-based model for typical features at VIV lock-in such as LCO and hysteresis phenomena. The vertical VIVs can be well captured by the DF-based model, while its capability of simulating the torsional VIVs requires further improvement. Furthermore, the predictive capability of DF-based model for vertical VIVs of bridge decks within a wide range of mass-damping conditions is highlighted.
Mingjie Zhang; Teng Wu; Fuyou Xu. Vortex-induced vibration of bridge decks: Describing function-based model. Journal of Wind Engineering and Industrial Aerodynamics 2019, 195, 104016 .
AMA StyleMingjie Zhang, Teng Wu, Fuyou Xu. Vortex-induced vibration of bridge decks: Describing function-based model. Journal of Wind Engineering and Industrial Aerodynamics. 2019; 195 ():104016.
Chicago/Turabian StyleMingjie Zhang; Teng Wu; Fuyou Xu. 2019. "Vortex-induced vibration of bridge decks: Describing function-based model." Journal of Wind Engineering and Industrial Aerodynamics 195, no. : 104016.
Accurate and efficient modeling of the wind field is critical to effective mitigation of losses due to the tropical cyclone-related hazards. To this end, a knowledge-enhanced deep learning algorithm was developed in this study to simulate the wind field inside tropical cyclone boundary-layer. More specifically, the machine-readable knowledge in terms of both physics-based equations and/or semi-empirical formulas was leveraged to enhance the regularization mechanism during the training of deep networks for dynamics of tropical cyclone boundary-layer winds. To comprehensively appreciate the high effectiveness of knowledge-enhanced deep learning to capture the complex dynamics using small datasets, two nonlinear flow systems governed respectively by 1D and 2D Navier-Stokes equations were first revisited. Then, a knowledge-enhanced deep network was developed to simulate tropical cyclone boundary-layer winds using the storm parameters (e.g., spatial coordinates, storm size and intensity) as inputs. The reduced 3D Navier-Stokes equations based on several state-of-the-art semi-empirical formulas were employed in the construction of deep networks. Due to the effective utilization of the prior knowledge on the tropical cyclone boundary-layer winds, only a relatively small number of training datasets (either from field measurements or high-fidelity numerical simulations) are needed. With the trained knowledge-enhanced deep network, it has been demonstrated that the boundary-layer winds associated with various tropical cyclones can be accurately and efficiently predicted.
Reda Snaiki; Teng Wu. Knowledge-enhanced deep learning for simulation of tropical cyclone boundary-layer winds. Journal of Wind Engineering and Industrial Aerodynamics 2019, 194, 103983 .
AMA StyleReda Snaiki, Teng Wu. Knowledge-enhanced deep learning for simulation of tropical cyclone boundary-layer winds. Journal of Wind Engineering and Industrial Aerodynamics. 2019; 194 ():103983.
Chicago/Turabian StyleReda Snaiki; Teng Wu. 2019. "Knowledge-enhanced deep learning for simulation of tropical cyclone boundary-layer winds." Journal of Wind Engineering and Industrial Aerodynamics 194, no. : 103983.
Despite the significant impacts of heavy rainfall on the tropical cyclone intensity due to the transfer of horizontal momentum between air and raindrops, the comprehensive modeling of rain-induced effects on the boundary-layer wind field remains a challenge. The wind shear zone developed surrounding the falling precipitation results in complicated dynamic interactions between the wind and rain fields. The solution of dynamically coupled, intensively interactive wind and rain fields may be achieved using high-fidelity air-water interaction simulations but needs extremely high computational costs. To consider the wind-rain interactions with a first-order approximation, the fully-coupled dynamic system governing the raindrop motion and the wind field has been simplified herein to a weakly-coupled one represented by aerodynamic drag force. The drag-induced horizontal momentum transfer is integrated into the governing equations of the linear, height-resolving wind field, and an analytical model is accordingly developed to effectively consider the rain-induced effects on the boundary-layer winds of tropical cyclones. The results generated by the present model are consistent with the field measurements. It has been demonstrated that, while the wind speed can be either accelerated or decelerated depending on the location in the tropical cyclones and the rain parameters (e.g., rain rate, relative motion between the air and raindrops, drag coefficient and raindrop size distribution), the rain-induced effects on the boundary-layer wind directions (and hence the inflow angle) also have important significance on the tropical cyclone wind hazard on tall buildings and other structures. Due to its simplicity and high computational efficiency, the proposed model could be easily implemented in the risk assessments for tropical-cyclone wind hazards in engineering applications.
Reda Snaiki; Teng Wu. Modeling rain-induced effects on boundary-layer wind field of tropical cyclones. Journal of Wind Engineering and Industrial Aerodynamics 2019, 194, 103986 .
AMA StyleReda Snaiki, Teng Wu. Modeling rain-induced effects on boundary-layer wind field of tropical cyclones. Journal of Wind Engineering and Industrial Aerodynamics. 2019; 194 ():103986.
Chicago/Turabian StyleReda Snaiki; Teng Wu. 2019. "Modeling rain-induced effects on boundary-layer wind field of tropical cyclones." Journal of Wind Engineering and Industrial Aerodynamics 194, no. : 103986.
Despite rapid development in computational fluid dynamics, semiempirical analyses based on parameters identified from spring-mounted sectional models are still widely used to examine wind-induced effects on bridges. In addition, wind tunnel results from full-bridge aeroelastic models, viewed as the most comprehensive representations, are typically a final check for wind design of long-span cable-supported bridges. There are several well-known limitations associated with conventional wind tunnel testing of both sectional and full-bridge models. For example, structural nonlinearities and large deformations are difficult to simulate in sectional models, and only a limited number of modes can be accurately simulated in full-bridge aeroelastic models. To advance aeroelastic modeling of flexible bridges in the wind tunnel, a slightly different version of the real-time hybrid simulation (RTHS) techniques, frequently used in various branches of engineering, is developed here. Specifically, the skeleton of the sectional or full-bridge model, characterizing the dynamic properties (e.g., mass, damping, and stiffness of the structure), is numerically simulated using computational structural dynamics, while its skin, characterizing the aerodynamic and aeroelastic properties, is physically modeled in the wind tunnel. Aerodynamic inputs (gusts) are applied directly on the skin in the wind tunnel, while aeroelastic inputs (motions) are represented by the simulation outputs of the bridge skeleton. On the other hand, the dynamic inputs to the bridge skeleton are acquired from the measured forces (and moments) on the bridge skin. The interactions between the skeleton and skin of the bridge are accomplished through a system consisting of sensors, a network of electromagnetic actuators, and controllers. The time history of the wind-induced bridge responses can be obtained at the end of the proposed real-time aerodynamics hybrid simulation (RTAHS). The feasibility of the RTAHS methodology is demonstrated by a numerical example involving both linear and nonlinear wind-induced forces on the bridge deck.
Teng Wu; Shaopeng Li; Mettupalayam Sivaselvan. Real-Time Aerodynamics Hybrid Simulation: A Novel Wind-Tunnel Model for Flexible Bridges. Journal of Engineering Mechanics 2019, 145, 04019061 .
AMA StyleTeng Wu, Shaopeng Li, Mettupalayam Sivaselvan. Real-Time Aerodynamics Hybrid Simulation: A Novel Wind-Tunnel Model for Flexible Bridges. Journal of Engineering Mechanics. 2019; 145 (9):04019061.
Chicago/Turabian StyleTeng Wu; Shaopeng Li; Mettupalayam Sivaselvan. 2019. "Real-Time Aerodynamics Hybrid Simulation: A Novel Wind-Tunnel Model for Flexible Bridges." Journal of Engineering Mechanics 145, no. 9: 04019061.
As buildings are designed to be taller and more slender, they become lighter and more flexible with less inherent damping. If left uncontrolled, excessive wind-induced building response can cause serious safety and serviceability issues. Additional damping provided by adding an auxiliary damping system to the tall building is considered as one of the most cost-effective means to suppress the wind-induced response. Typically, the performance of these damping systems is evaluated experimentally with scaled damper and building models. However, the simplified small-scale dampers may not truly reflect the complex behavior of the full-scale damping systems. To realize the effective reduction of the wind-induced response of tall buildings, a real-time aerodynamics hybrid simulation (RTAHS) methodology that can offer improved response evaluation of a tall building integrated with an auxiliary damping system is introduced in this study. In this novel dynamic testing approach, the accurate evaluation of wind-induced tall building response is achieved by interacting an aeroelastic model of the tall building with the numerical model of the full-scale damper via interfacing actuators during the wind-tunnel tests. The feasibility and simulation accuracy of the proposed dynamic testing technique in the wind tunnel is numerically demonstrated by two case studies involving the wind-induced response reduction of a tall building equipped with both small-scale and full-scale damper properties.
Teng Wu; Wei Song. Real-time aerodynamics hybrid simulation: Wind-induced effects on a reduced-scale building equipped with full-scale dampers. Journal of Wind Engineering and Industrial Aerodynamics 2019, 190, 1 -9.
AMA StyleTeng Wu, Wei Song. Real-time aerodynamics hybrid simulation: Wind-induced effects on a reduced-scale building equipped with full-scale dampers. Journal of Wind Engineering and Industrial Aerodynamics. 2019; 190 ():1-9.
Chicago/Turabian StyleTeng Wu; Wei Song. 2019. "Real-time aerodynamics hybrid simulation: Wind-induced effects on a reduced-scale building equipped with full-scale dampers." Journal of Wind Engineering and Industrial Aerodynamics 190, no. : 1-9.
To ensure acceptable performance for survivability, serviceability and habitability of the mega-tall buildings, it is necessary to study their wind-induced response characteristics and vortex-induced resonance mechanism. In this study, the wind-induced responses of a thousand-meter-scale four-tower-connected mega-tall building are investigated using the aeroelastic model test in a boundary layer wind tunnel. The results show that the root mean square across-wind tip displacement increases dramatically within a certain wind velocity range at 60°wind direction, which indicates that the vortex-induced resonance occurs. Accordingly, the relation between the aerodynamic damping ratio and reduced wind velocity is further studied at this wind direction. Furthermore, the underlying mechanism of vortex-induced vibration (VIV) is comprehensively discussed based on the amplitude spectra of the across-wind tip displacements, which facilitates the identification of corresponding lock-in region. The identified critical reduced wind velocity for vortex-induced resonance for the mega-tall building is 10.19, with a lock-in region from 10.19 to 11.70. In addition, the VIV-like phenomenon occurred in the along-wind direction for this complex mega-tall building, associated with VIV in the across-wind direction. This observation indicates that there is aerodynamically coupled vortex shedding of the mega-tall building in the two directions. This study contributes to a detailed insight of the VIV phenomenon for the thousand-meter-scale four-tower-connected mega-tall building, and hence facilitates the wind-resistance design of this type of flexible structures.
Chaorong Zheng; Zhao Liu; Teng Wu; Haifeng Wang; Yue Wu; Xindong Shi. Experimental investigation of vortex-induced vibration of a thousand-meter-scale mega-tall building. Journal of Fluids and Structures 2018, 85, 94 -109.
AMA StyleChaorong Zheng, Zhao Liu, Teng Wu, Haifeng Wang, Yue Wu, Xindong Shi. Experimental investigation of vortex-induced vibration of a thousand-meter-scale mega-tall building. Journal of Fluids and Structures. 2018; 85 ():94-109.
Chicago/Turabian StyleChaorong Zheng; Zhao Liu; Teng Wu; Haifeng Wang; Yue Wu; Xindong Shi. 2018. "Experimental investigation of vortex-induced vibration of a thousand-meter-scale mega-tall building." Journal of Fluids and Structures 85, no. : 94-109.
The nonstationary winds during tropical cyclones and non-synoptic events have been extensively observed and analysed; however, the significance of nonstationarity in the consideration of wind load effects has not been widely investigated yet. In this study, the effects of nonstationarity on changing bridge aerodynamics have been discussed from both linear and nonlinear viewpoints. For linear aerodynamics change, the conventional 1-D indicial response function has been extended to a 2-D case since an additional time scale, resulting from the time-varying transient nonstationarity, is introduced in the wind–structure interactions. For nonlinear aerodynamics change, the conventional hybrid model has been generalized to consider the additional effective angle of attack due to the time-varying mean wind speed. The bridge buffeting response under the tropical-cyclone and downburst winds were comprehensively examined based on 1-D semi-empirical linear model, 2-D semi-empirical linear model, 1-D hybrid nonlinear model, 1-D generalized hybrid nonlinear model and 2-D generalized hybrid nonlinear model, where the ability of these models to capture the changing linear and/or nonlinear bridge aerodynamics under nonstationary winds is highlighted. The results demonstrated the important effects of the transient nature of nonstationary winds on the changing bridge aerodynamics and hence on the structural response.
Teng Wu. Changing Bridge Aerodynamics under Nonstationary Winds. Structural Engineering International 2018, 29, 74 -83.
AMA StyleTeng Wu. Changing Bridge Aerodynamics under Nonstationary Winds. Structural Engineering International. 2018; 29 (1):74-83.
Chicago/Turabian StyleTeng Wu. 2018. "Changing Bridge Aerodynamics under Nonstationary Winds." Structural Engineering International 29, no. 1: 74-83.
Lingyao Li; Teng Wu; Xuhui He; Jianming Hao; Hanfeng Wang; Hanyong Xu. Erratum for “Reliability Evaluation of Vortex-Induced Vibration for a Long-Span Arch Bridge” by Lingyao Li, Teng Wu, Xuhui He, Jianming Hao, Hanfeng Wang, and Hanyong Xu. Journal of Bridge Engineering 2018, 23, 08218001 .
AMA StyleLingyao Li, Teng Wu, Xuhui He, Jianming Hao, Hanfeng Wang, Hanyong Xu. Erratum for “Reliability Evaluation of Vortex-Induced Vibration for a Long-Span Arch Bridge” by Lingyao Li, Teng Wu, Xuhui He, Jianming Hao, Hanfeng Wang, and Hanyong Xu. Journal of Bridge Engineering. 2018; 23 (10):08218001.
Chicago/Turabian StyleLingyao Li; Teng Wu; Xuhui He; Jianming Hao; Hanfeng Wang; Hanyong Xu. 2018. "Erratum for “Reliability Evaluation of Vortex-Induced Vibration for a Long-Span Arch Bridge” by Lingyao Li, Teng Wu, Xuhui He, Jianming Hao, Hanfeng Wang, and Hanyong Xu." Journal of Bridge Engineering 23, no. 10: 08218001.
The existence of the super-gradient-wind region, where the tangential winds are larger than the gradient wind, has been widely observed inside the hurricane boundary layer. Hence, the extensively used log-law or power-law wind profiles under near-neutral conditions may be inappropriate to characterize the boundary layer winds associated with hurricanes. Recent development in the wind measurement techniques overland together with the abundance of data over ocean enabled a further investigation on the boundary layer wind structure of hurricanes before/after landfall. In this study, a semi-empirical model for mean wind velocity profile of landfalling hurricanes has been developed based on the data from the Weather Surveillance Radar-1988 Doppler (WSR-88D) network operated by the National Weather Service and the Global Positioning System (GPS) dropsondes collected by the National Hurricane Center and Hurricane Research Division. The proposed mathematical representation of engineering wind profile consists of a logarithmic function of the height z normalized by surface roughness z0 (z/z0) and an empirical function of z normalized by the height of maximum wind δ (z/δ). In addition, the consideration of wind direction in terms of the inflow angle is integrated in the boundary layer wind profile. Field-measurement wind data for both overland and over-ocean conditions have been employed to demonstrate the accuracy of simulation and convenience in use of the developed semi-empirical model for mean wind velocity profile of landfalling hurricanes.
Reda Snaiki; Teng Wu. A semi-empirical model for mean wind velocity profile of landfalling hurricane boundary layers. Journal of Wind Engineering and Industrial Aerodynamics 2018, 180, 249 -261.
AMA StyleReda Snaiki, Teng Wu. A semi-empirical model for mean wind velocity profile of landfalling hurricane boundary layers. Journal of Wind Engineering and Industrial Aerodynamics. 2018; 180 ():249-261.
Chicago/Turabian StyleReda Snaiki; Teng Wu. 2018. "A semi-empirical model for mean wind velocity profile of landfalling hurricane boundary layers." Journal of Wind Engineering and Industrial Aerodynamics 180, no. : 249-261.