Wind Action Research Articles

Influence of Pile-Soil Interaction on Dynamic Properties and Response of Offshore Wind Turbine with Monopile Foundation in Sand Site

In this study, a sophisticated 3D finite element model of NREL 5MW wind turbine (WT) superstructure is developed using Abaqus, which includes necessary functional features, such as rotor rotation, drivetrain, pitch, servo-control, etc. A multi-step validation process has been conducted in order to verify the reliability of the blade, the Rotor-Nacelle Assembly (RNA) and the entire WT model. In the time domain, a software framework of ABA-OWT is developed for the dynamic analysis of offshore wind turbine (OWT) based on the Abaqus WT structure model and FAST submodules. The framework is capable of computing wind loads, wave loads, and servo-control commands in a fully coupled way. The pile-soil interaction (PSI) is modeled by nonlinear p-y, t-z and Q-z springs and the dashpots parallel with them. A typical sandy site is considered, while several identical analyses are performed for both numerical models including fixed base and PSI. After calculating the eigenvalues of the WT structure and analyzing its dynamic response to the combined action of wind and wave, three representative wind-wave load cases are chosen for subsequent seismic response study. The important conclusions are as follows. Firstly, the PSI reduces the natural frequencies of FA1, SS1 and FA2 by about 12% and SS2 by 23.5%. Secondly, under the combined action of wind and wave, the PSI significantly increases the tower-top peak motion responses in normal operating cases, but its influence on the mudline peak internal force responses is almost negligible; For parking cases, the PSI dramatically enlarges the peaks of the tower-top motion responses and the mudline bending moment, and the effect of PSI on the structural peak responses in parking cases is greater than that in normal operating cases. Finally, under the conjoint action of wind, wave and seismic, the PSI increases the tower-top peak motion responses and reduce the mudline peak internal force responses, and because of the aeroelastic effects, the influence of PSI on the structural peak responses in normal operating cases is always the smallest. In a word, the PSI has a remarkable impact on the natural frequency, dynamic response and seismic response of offshore wind turbine (OWT) with monopile foundation, which should be considered in a reasonable way in the practical offshore wind power project.

ANTHROPOGENIC IMPACTS ON THE MORPHOLOGICAL EVOLUTION OF THE PACOTI ESTUARY, NORTHEAST BRAZIL

The problem of anthropogenic occupation on the banks of estuaries and rivers has been a factor of concern and frequently addressed around the world. In the State of Ceará, this problem has been persistent, despite the reasonable environmental legislation dealing with this issue. Along the Pacoti River Estuary, this problem was addressed in this study and added to the analysis of the wind action in the evolution of this coastal environment. Thus, direct and indirect methods were applied, mainly based on field work and remote sensing based in the use of tools from a GIS platform. The results show persistent and continuous participation of aeolian activity, notably dunes migration, in the evolution process of this estuary. Additionally, human interference over 63 years, whether in the form of exploitation of natural resources and/or urban occupation on the banks of the estuary and in the possible area of ​​expansion of this environment, has produced serious environmental damage and restricted the natural area of this important coastal ecosystem. This process of environmental degradation was largely accelerated from the occupation of the area to the east of the estuary by the Beach Park development, and to the west by the Alphaville Residential Condominium.

Dynamic analysis of the wind-wave-current-bridge system considering pile-soil interaction

Coastal bridges are normally confronted with a complex marine environment including wind, wave and current. Present researches rarely take the current action and pile-soil interaction into consideration. It is thus essential to conduct the dynamic analysis of the cable-stayed bridge under wind-wave-current action considering pile-soil interaction. A coupled wind-wave-current-bridge (WWCB) system is proposed in this study to help understand the bridge dynamic performance. In the WWCB system, the bridge model is established through the finite element method, and the pile-soil interaction is considered through the pile-soil solid contact (PSSC) model. The wave-current action is obtained through a numerical wave tank, while the wind is simulated as the stochastic random process and generated with spectrums. The initial geostress, mass and density distribution are also considered in the WWCB system. To illustrate the bridge dynamic characteristics, dynamic responses under different load combinations are presented. Furthermore, the natural frequency and spectral density function comparison between the consolidation model, PSSC model and soil-spring model are provided to investigate the influence of the pile-soil interaction. The results show that different from previous conclusions, the wave-current action plays the dominant role instead of the wind action in some cases when considering the pile-soil interaction. Additionally, the consideration of the pile-soil interaction would decrease the structural stiffness, resulting in lower natural frequencies and wider frequency distribution. Consequently, the influence of the wave-current action and pile-soil interaction should be noted in the practical engineering.

PARAMETRIC ANALYSES OF AN ABSORPTION REFRIGERATION SYSTEM WITH WATER AND LITHIUM BROMIDE IN STEADY STATE POWERED BY SOLAR ENERGY

The demand of energy utilization is increasing expressively as fast as the development of countries. Besides being available everywhere and virtual inexhaustible, renewable energy is undoubtedly necessary to avoid depleting the planet’s natural resources and global warming. Even considering the primordially environmental importance, the result of no emissions by renewable energy grant attractive also for political and economics statement. It should be noted the sun is the most abundant primary energy source in the planet and essential for eco-friendly process like photosynthesis, wind action, water cycle as well direct uses as electric and thermal generations. Consequently, nowadays several methodologies have been applied in order to transfer energy between the cycle and its surroundings optimizing for instance the coefficient of performance and heat exchangers. An absorption system is widely applied in these cases due to supply a unique solution for a range of technological problems from solar cooling to steam-driven refrigeration. Alternatively, this article main objective is modulating an absorption refrigeration system (ARS) which uses water-lithium bromide as a working fluid. Therefore, using the software Engineering Equation Solver (EES) is possible to obtain a thermodynamic single effect code that allows elaborating parametric analyses. In other words, performed and verified the influence of some input parameters over other output parameters. First, it was necessary to consider the cycle operating as reversible and steady state. Furthermore, it is assumed that no chemical reactions occur between water and lithium bromide. Thus, in the meantime apply the heat exchangers and a Solar Collector to receive the thermal energy and provide to the refrigeration cycle. Similarly, water from external sources was used to change heat with the fluid water-lithium bromide. Satisfactory results were founded and it enable to calculate and evaluate all system heat transfers rates and coefficient of performance. Almost all of input parameters introduced brought adequate values over output parameters, but the most convenient were: mass balance of water-lithium bromide solution and temperature of cold water from outside source. Clearly, results always can be found but in conclusion this article can be used to verify parameters sensitivity, optimized absorption refrigeration solutions and supply knowledge for future applications.

Beach Environment along the Coastal Stretch of West Bengal

Beach is one of the most conspicuous geomorphic features of a coastal region. Interpretation of any beach environment warrants detailed analysis of its morphological features, prevailing hydrodynamic conditions, actions of wind and cyclonic surges which bring discernible changes in the coastal configurations. Various beach features have been dealt here in details.

Service-Life Damage Assessment of a Reinforced Concrete Structure under Multi-Hazard Seismic and Wind Actions

Service-Life Damage Assessment of a Reinforced Concrete Structure under Multi-Hazard Seismic and Wind Actions

Wind Action Effects on Heliostat – CFD and FEM Study

Heliostats account for 45% of the total cost of a solar power tower, so optimizing their structural is critical to overall plant viability. Static wind charging of heliostats, as well as forces and moments applied by steady wind in any weather, has a high impact on the heliostat components design. For the reason that wind tunnel testing is expensive and the profile of flow field is difficult to obtain, numerical wind tunnel was used to study the wind load of the heliostat by Computational Fluid Dynamics (CFD) method and a (FEM) method. A 3D simulation has been performed for the Algerian climate, to evaluate this effect at different configurations of the heliostat. This paper provides details about the mesh generation method applied to complex projects under different working conditions. The effects of wind direction, azimuth and elevation angles on the wind pressure distribution are summarized. The coefficients of drag, lift and moment under diverse operating conditions were calculated. The CFD models of the wind around the heliostat are validated to the theoretical and experimental data.

Tuning Ice Nucleation by Mussel-Adhesive Inspired Polyelectrolytes: The Role of Hydrogen Bonding

Tuning Ice Nucleation by Mussel-Adhesive Inspired Polyelectrolytes: The Role of Hydrogen Bonding

Influence of Wind Angle Incidence and Architectural Elements on the External Pressure Coefficient of Hyperbolic Paraboloid Roofs

In the study of wind loads in buildings, the aerodynamics of roofs with parabolic shapes, which cause complex pressure distributions due to their sensitivity to wind, are often omitted and neglected by several codes and norms. In this way, computer simulations are a viable and reliable alternative. Here, wind action was considered in an innovative project composed of parabolic and circumferential generatrices: the Church of Saint Francis of Assisi. Designed by Brazilian architect Oscar Niemeyer in Belo Horizonte, Brazil, two paraboloid vaults and three circular arches of reinforced concrete composed its structure. This work generated great international recognition for the architect after 1943, as the design of the roofs did not require walls. For geometry modeling, Autodesk AutoCAD software was adopted, and the models were considered in a control volume. The simulations were performed using Ansys Workbench software and the RNG K-Epsilon turbulence model. The wind speed at different heights was calculated using the Power-law approximation. A basic wind speed of 30 m/s was adopted, and the mesh used was composed of tetrahedrons. To validate the methodology, different models with hyperbolic-paraboloid roofs from the literature were considered. In addition, the visualization of the flow around the geometry from the streamlines, the wind profile, and the analysis of the isobaric lines of the external pressure coefficients for different directions of incidence and architectural elements that make up the building were presented.

Detection range of two acoustic transmitters in four reservoir habitat types using passive receivers

BackgroundRecently, South Dakota Department of Game, Fish, and Parks (SDGFP), has undertaken a suite of rigorous acoustic telemetry studies. The goals and scope of the individual research projects vary but all use the same receiver array throughout Lake Sharpe in central South Dakota. Prior to initiating the telemetry studies, we sought to describe the detection probability of receivers from a representation of habitats within Lake Sharpe, South Dakota. We used both a V9-2H transmitter and a V13-1L transmitter in combination with VR2W 69 kHz passive receivers [all from Innovasea (Vemco)] to determine detection probability in four novel habitats of Lake Sharpe. Both transmitter and receiver were moored at fixed distances (200 m 400, and 600 m) for multiple consecutive days and detection probability compared between transmitter type, distance, site, and diel period using ANOVA following arcsine square-root transformation.ResultsWe found significant differences in detection probability between the four habitat types for both the V9 and V13 transmitters. Sites protected from wind and wave action, and with little boat traffic, had larger detection ranges compared to areas that were wind exposed and host more boat traffic. The site immediately downstream from a hydroelectric dam that is exposed to both high wind fetch and is popular for boating, exhibited the poorest detection probability at all distances for both transmitter types. V13 transmitters consistently exhibited greater detection probability relative to V9 transmitters and this difference was greater at further distances. In general, detection probability was higher at nighttime compared to daytime and these differences were significant dependent on transmitter, site, and distance.ConclusionsUsing the information presented, SDGFP has modified their receiver array to maximize the ability to detect acoustic transmitters in the novel habitats of Lake Sharpe. Specifically, receiver spacing was reduced and/or expanded dependent on the distance, where 50% detection probability was attained. More work is needed to identify those factors that influence detection probability of acoustic telemetry systems.

Numerical Investigation of Wind Pressure Coefficients on Different Scallop Dome Configurations

The effects of the action of wind on scallop domes were numerically investigated using the software Ansys, as well the interference of the neighborhood on the external pressure coefficient and the streamlines between geometrically identical domes. The influence of the proportion on the neighborhood interference in scallop domes and the variations in the dimensions of the structures on the pressure coefficients and streamlines were also investigated. Five simulations were analyzed involving six-grooved domes and geometry height variations for validation. The numerically obtained coefficients were compared with values in the literature. Other applications investigated the influence of grooves on the external pressure coefficient and the effect of wind on the grooved domes. Another application analyzed the interference of the neighborhood on the external pressure coefficients and streamlines between three geometrically identical domes and, finally, the influence of the proportion in the study of the interference of the neighborhood. Here, the variations in the dimensions of the structure affected the pressure coefficients and the streamlines were analyzed. It was possible to verify the versatility and efficiency of the computational method used in the analysis of the action of wind.

Field Investigation on the Coastal Erosion and Progradation Evolution of the Binzhou Shelly Chenier in China: Comparisons between Normal and Typhoon Hydrodynamics

The shelly chenier is a dike-like accumulation formed by waves, currents, and other hydrodynamic forces pushing the shells and their debris in the intertidal zone to the high tide line. It is a special type of coastal dike. The shelly chenier located in Wangzi Island of northern Shandong Province is the last well-preserved chenier of the Bohai Bay with natural attributes exposed on the surface. It has unique and irreplaceable attributes among the shell beaches of China. Based on remote sensing interpretation, field investigation, and GPS-RTK (Real-Time Kinematic) measurement, this paper investigates the coastal erosion and progradation evolution of the Binzhou Shelly Chenier in China usingcomparisons between normal and typhoon hydrodynamics. The results show that: (1) There are two kinds of shelly chenier in the study area, the first is “the tidal channel shelly chenier” which is significantly affected by the tidal current, and the second is “the open shelly chenier”, which is significantly affected by direct scouring and silting of waves. The open shelly chenier is continuously eroding under the normal hydrodynamics and the shell beach is supplied by a large number of shells and their debris under the typhoon hydrodynamics, while the tidal channel shelly chenier is gradually developed due to the action of alongshore currents and in–out flows. (2) The energy of waves and currents under normal hydrodynamics is insufficient to transport the shells and their debris in the intertidal zone to the shell-beach. On the contrary, the continuous action of waves makes the shells and their debris on the open-shell beach finer and transports the shells and their debris to the sea causing erosion and retreat of the shelly chenier. (3) The action of typhoons and other strong winds and waves results in the original accumulation on the open shell-beach being further transported to the land and provides a large amount of shells and debris from the intertidal zone to the shelly chenier. Based on GPS-RTK monitoring data from 2020–2021, it was found that the transport volume of shells and debris caused by a typhoon storm surge is equivalent to the annual transport volume under normal ocean dynamics.

Performance of cable-supported glass façades under time-depending wind action

Cable supported glass façades are sensitive to wind action because of their flexibility. Conventional laboratory testing to check a façade reliability under the wind action is generally carried out by uniformly air pressure tests. However, the typical wind action on a surface is known to be not uniform because it varies due to building aerodynamics and wind flow turbulence, and this aspect should be properly considered for testing protocols. This paper discusses the structural response of cable-supported glass façades, through time history finite element (FE) analyses, under different wind action combinations that varies based on the building aerodynamics (plan shapes and roof curvatures), the wind direction (0° and 90°), and the glass panel position (up and down). Such a finding is further enforced by the presence of flexible supports for the constituent glass modules. The presented results show a strong dependence of the structural response on the wind action configuration, and thus suggest the need of new testing protocols for similar systems.

Reinforcement Design of the Support Frame of a Petrochemical Heater

In this paper, we investigated the operating security of the support frame of a petrochemical heater under the action of a strong wind. When the fatigue limit was exceeded, the support frame was damaged. We monitored the heater before reinforcement and then applied the finite element method to analyze and compare nine different kinds of reinforcement methods for the support frame. From the results of the finite element analysis, fatigue failure of the support frame before reinforcement occurred at locations where the computed stresses from the finite element analysis were large, thus partially justifying the adequacies of the present analysis methods and results. Among the nine reinforcement methods, we suggest case 9 to reinforce a support frame so that its operating security under the action of a strong wind can be improved. At the end of this paper, several future studies are suggested, including verification of the reinforcement for the support frame and the establishment of the system for automatic stress monitoring and analysis.

Frequency domain modeling of long-span sea-crossing bridge under stochastic wind and waves

In this study, a frequency domain modeling framework that assembles aero- and hydro-dynamic approaches to characterize the structural motions of a long-span sea-crossing bridge under stochastic wind and waves is proposed as an efficient alternative for the conventional time-consuming time domain analysis. The improved quasi-steady buffeting model is employed to investigate the fluctuating wind actions on structural components and the aero-elastic effect of bridge decks. Potential flow theory associated with constant boundary element method is applied to calculate the linear as well as quadratic hydrodynamic transfer functions and both first- and second-order wave loads are considered and coupled in the modeling framework. The proposed methodology is well validated using a benchwork experiment of a flexible cylinder subjected to wind and waves. The dynamic performance of a long-span sea-crossing bridge under extreme wind and wave conditions is modeled using the proposed framework. The effects of wind and waves, different mode combinations, directionality and nonlinear wave loads on global responses are discussed. In the proposed approach, a combination of only a few main modes is necessary to yield plausible displacement responses of bridge deck, while more modes are required to obtain converged internal force responses.

Size and Shape Optimization of a Guyed Mast Structure under Wind, Ice and Seismic Loading

This paper discusses the size and shape optimization of a guyed radio mast for radiocommunications. The considered structure represents a widely industrial solution due to the recent spread of 5G and 6G mobile networks. The guyed radio mast was modeled with the finite element software SAP2000 and optimized through a genetic optimization algorithm (GA). The optimization exploits the open application programming interfaces (OAPI) SAP2000-Matlab. Static and dynamic analyses were carried out to provide realistic design scenarios of the mast structure. The authors considered the action of wind, ice, and seismic loads as variable loads. A parametric study on the most critical design variables includes several optimization scenarios to minimize the structure’s total self-weight by varying the most relevant parameters selected by a preliminary sensitivity analysis. In conclusion, final design considerations are discussed by highlighting the best optimization scenario in terms of the objective function and the number of parameters involved in the analysis.

Advances in the application of the Principal Static Wind Loads: A large-span roof case

In this paper, a procedure to define a small set Multi-target Equivalent Static Wind Loads (M-ESWLs) that allows for the verification of a large set of structural elements of a stadium roof is presented and applied to a real case. The methodology, based on the combination of the so-called Principal Static Wind Loads (PSWLs), is aimed at reducing the subjectivity of the designer in the identification of the most challenging structural conditions induced by wind actions, and therefore it allows to simplify and speed up the wind-resistant design process of roof structures.Starting from wind tunnel tests on a scaled rigid model of a stadium, the dynamic response of its roof is computed by loading the finite element model of the structure with the time histories of the spatially averaged net pressures acting on its surface. The time histories of the internal forces acting in a set of structural members are reconstructed, and the target envelope is built by identifying, for each of them, a maximum and a minimum value through a statistical analysis of the time series. For each of these extreme conditions an ESWL is identified, PSWLs are computed and combined by means of a genetic algorithm, and the set of M-ESWLs, able to match the envelope, is defined. To limit the number of M-ESWLs, a nonlinear constrained optimization is implemented in the PSWLs combination, also introducing the possibility to over-dimension some structural members.It is concluded that the application of this methodology allows the designer to select a limited number of M-ESWLs that can be used in an automated way in order to verify the response of a defined set of structural elements.

Stiffness requirements for wind girders in open-top cylindrical steel tanks

Aboveground cylindrical storage tanks are very thin shell structures which are prone to buckling when subjected to wind pressure. Both external and internal pressures are developed due to wind action, and the magnitudes of the pressures generally vary around the circumference. A wind girder is generally used in open-top cylindrical tanks to increase their resistance against buckling. The wind girder must have adequate strength and stiffness in order to fulfill its function properly. Widely used design specifications provide recommendations for the design of the wind girder. Strength requirements are given in terms of stress resultants, while a minimum second moment of area is provided as a stiffness requirement. The recommendations for the stiffness requirement were developed by conducting Linear Elastic Bifurcation Analysis (LBA) of cylindrical shells subjected to uniform external pressure. This paper explores stiffness requirements for the wind girder in open-top cylindrical steel tanks. The relationship between the buckling strength and the second moment of area of the wind girder was explored through a finite element parametric study. Tank shells with different radius-to-thickness and height-to-diameter ratios and having different wind girder sizes were investigated by means of LBA. A buckling strength curve was developed based on the LBA results where the strengths can be predicted with 90% accuracy. In addition, a new second moment of area requirement was proposed. The parametric study was extended to investigate the behavior using Geometrically Nonlinear Analysis including Imperfections (GNIA). The same tank geometries were studied using GNIA and considering different imperfection amplitudes. A buckling strength curve, which takes into account imperfection amplitudes, was developed to be used in design.

Seismic Retrofitting of Existing Industrial Steel Buildings: A Case-Study

Industrial single-storey buildings are the most diffuse typology of steel construction located in Italy. Most of these existing buildings were erected prior to the enforcement of adequate seismic provisions; hence, crucial attention is paid nowadays to the design of low-impact retrofit interventions which can restore a proper structural performance without interrupting productive activities. Within this framework, an existing industrial single-storey steel building located in Nusco (Italy) is selected in this paper as a case-study. The structure, which features moment resisting (MR) truss frames in both directions, is highly deformable and presents undersized MR bolted connections. Structural performance of the case-study was assessed by means of both global and local refined numerical analyses. As expected, the inadequate performance of connections, which fail due to brittle mechanisms, detrimentally affects the global response of the structure both in terms of lateral stiffness and resistance. This effect was accounted for in global analyses by means of properly calibrated non-linear links. Thus, both local and global retrofit interventions were designed and numerically investigated. Namely, lower chord connections were strengthened by means of rib stiffeners and additional rows of M20 10.9 bolts, whereas concentrically braced frames (CBFs) were placed on both directions’ facades. Designed interventions proved to be effective for the full structural retrofitting against both seismic and wind actions without limiting building accessibility.

Atmospheric wind pressure distribution on an isolated agricultural silo / Distribuição da pressão atmosférica do vento em um silo agrícola isolado

Storage silos installations are very common in the agricultural areas of Argentina and Brazil. Accidents caused by the action of the wind on the structural components of silos are usually reported. For this reason, the UTN - Regional Rafaela and the Laboratorio de Aerodinámica of the UNNE began to develop experimental studies in a wind tunnel with the objective of analyzing the external pressure distribution on isolated silos and complementing the procedures established in the Argentine Wind Code CIRSOC 102 and in the Brazilian Code NBR 6123. The tests were carried out in the UNNE “Jacek P. Gorecki” wind tunnel, which is a boundary layer tunnel of the Eiffel-type. The total length of the tunnel is 39.65 m, the test section is 2.4 m wide × 1.8 m high × 22.8 m long and an axial fan generates a maximum speed of 25 m/s. Turbulence generators and surface roughness elements were used to simulate atmospheric wind and then a 1:100 scale model of the silo was tested. In this work, results of mean and fluctuating pressure values obtained by wind tunnel tests are presented. The turbulent wind actions defined by the fluctuating pressures are evaluated through the distributions of RMS and peak values.