Wind Engineering

Developing precise and robust algorithms that can help in obtaining maximum power yield in a variable speed wind turbine is an important area of research in wind engineering. The present manuscript proposes a technique that utilizes a second-generation CRONE controller for the maximum power tracking technique (MPPT) to maximize power generation in a wind energy conversion system (WECS) based on a double-fed induction generator (DFIG). The authors propose this novel method because the classical controllers cannot provide adequate performance in terms of extracting the maximum energy from variable speed wind turbines when applying a real wind profile and they cannot guarantee the high stability of the WECS. Moreover, this novel controller sufficiently handles problems related to the control effort level. The performance of the second-generation CRONE method was mathematically modeled using MATLAB/Simulink and compared with four other types of MPPT control techniques, which include a p...

A number of studies exist on the relationship between climatic factors and malaria prevalence. However, due to scarcity of data, most of the studies are based on biophysical experiments and do not control for socioeconomic covariates. This research, which uses data on Ghana, contributes to the thin literature that addresses this limitation. We found that humidity and rainfall predict malaria prevalence. Furthermore, our results suggest that malaria prevalence increases with rainfall, the proportion of middle income households, and the proportion of households with no formal education. The corresponding elasticity coefficients are 0.67, 0.12 and 0.66, respectively. Significant differences in the prevalence rate have also been observed across regions.

The work involves developing geometric Model for G 4 Commercial Building constructions in seismic zone III by utilizing steel-concrete composite construction. The suggested structure is eighteen.75 m height (each floor height 3.75m) with plan dimensions 30m x 18m. The geometric modeling from the structure is recognized as with minimum drift and moments in line with the is a result of analysis (STRAP software). The cost-effective style of composite people are achieved by implementation of encased steel posts, universal beam section with profiled metal deck slabs (composite floors) with implementation of semi rigid connections in beam-column and foundation system. Because the structure is situated in seismic zone III, ductile performance from the people and strong column -weak beam action is offered due factors by applying the attached codes are applied according to Indian Standards, Euro code -4 and British standards BS-5950, to exhibit optimum structural performance. In the finish from the project a comparative study done between RCC presented & Composite construction regarding cost & structural performance.

The effect of wind as a dynamic load on structures can vary greatly depending on geographic location, topography, building height, and the characteristics of the building itself. Therefore, careful calculations and an in-depth understanding of these factors are essential in the design of safe wind-resistant structures. For tall buildings, the structural response due to horizontal loads due to wind loads is much greater than vertical loads. This paper reviews the analysis of wind loads as static lateral loads against the internal forces and inter-story drift that occur. A review was carried out of a reinforced concrete structure building with a plan size of 25 x 10 m; the frame height is 32 m, with a total of 8 floors. The speed of the wind is 120 mph. The structural response reviewed compares internal forces, deformation, and inter-story drift under wind loads with variations of wind speed factors based on surface roughness and topographic influence factors (slopes and hills). From the analysis of the effect of wind loads on building structures, it can be seen that wind speeds in flat areas without obstructions (exposure D) and slope areas have more significant wind speeds compared to the city center and hilly regions.

Numerical simulations are carried out to analyse the impact of tornadic load on a tall building. For the present study a one-celled tornado replicating a real EF-2 scale has adopted. A standard tall building based on the Commonwealth Advisory Aeronautical Research Council (CAARC) is used. For detail analysis, the tornado is placed in three different locations with respect to the center of the building. These locations are at the tornado center, at the core radii and outside core radii. As the building has rectangular cross section (plan wise), two different orientation of the building with respect to the center of the buildings are considered. Irrespective of the orientation of the building, higher suction obtains when the center of the building coincides with the center of the tornado and it started to decrease as the tornado center moves away from the building center. This happens due to the ground pressure distribution which dominates the overall pressure distribution along the f...

International audienceWind tunnels are usually designed for a prerequisite purpose. Wind tunnels for aeronautical studies aim at reproducing very low turbulence flow at high speed, what they attain through a settling chamber and funnelling effect with a contraction ratio of the section by 8 to more, BLWT are designed for making a boundary layer grow, what means a long flat floor upstream the model and industrial wind tunnel are designed with a continuous flat floor allowing forklifts and other handling vehicles to travel inside. It is therefore difficult to change the initial destination of a wind tunnel, pulling down walls and rebuilding is costly. In order to overcome this issue, an innovative device has been developed for the Jules Verne large climatic wind tunnel, with the aim to modulate its section, opening it to new markets. This device allows a fast and cheap adaptation of the size and shape of the wind tunnel section. Experience of the wind tunnel team with inflatable struc...

Atmospheric Boundary layer wind tunnels (ABLWT) dedicated to building safety and comfort have been operated by CSTB in Nantes since 1971. Because ABLWT only deal with reduced scale models of real structures, the necessity of a larger wind tunnel, the Jules Verne Climatic wind tunnel (CWT), able to reproduce extreme wind loads on real scale structures arose in the years 80. Hence, it became a major European facility operating for improvement of the safety, quality and environmental impact of buildings and civil engineering works as well as products from industrial fields (transportation, energy…) with respect to strong winds and other climatic hazards. Both wind tunnel types, the ABLWT and the CWT are complementary and used for studying the effect of wind on the same structures at two different scales, when the effect of wind scaling is important. During the 2018 year, several modifications were made to the CWT facility. The atmospheric test section of the existing facility was elong...

The consistency of measurements in various wind tunnels is of concern to designers and code writers. This study attempts to quantify the variability of wind effects estimates based on tests conducted at six wind tunnel laboratories. Pressure tap measurements were made on wind tunnel models of four buildings. Comparisons were made between estimated 50th percenttiles of ͑1͒ peak positive moments in a frame section near the knee joint and ͑2͒ peak pressure coefficients of a roof tap nearest a building corner. Modeling of suburban terrain contributes significantly to the variability. Other factors are eave height, wind direction, and frame location within the building. Coefficients of variation were about 10-40%. A subsequent phase of this research entails a detailed analysis of the reasons for the variabilities. The results could help future improvement of wind load factors that account for all relevant uncertainties in the estimation of wind effects and efforts to improve and standardize wind tunnel simulations.

Simple static behaviour of wind loading, which is universally applied to design of typical low to medium-rise structures, can be satisfactorily inappropriately conservative for design of high-rise buildings. This conservativeness could be due to several reasons, and one such factor could be the blind use of analysis and design software’s. Most cases the user have little access to the main program frame either for auditing or otherwise. It is highly probable that the resulting outcomes from such interfaces might lead to erroneous results and possible under or over estimations. Additionally, the simplified treatment for deriving lateral loads has issues in addressing challenges such as the effects of resonance, acceleration, damping, structural stiffness, interference from other structures, e.t.c.. These are all important factors in wind design considerations for high-rise buildings. Hence, this paper provides an assessment for high-rise building wind design using both software’s and ...

This study compares the aerodynamic behaviour of medium rise multi-storey frame structures with and without shear walls using the local wind gust of Maiduguri (47m/s) as primary data. The wind assessment was carried out in accordance with recommendations of British Standard and other relevant specifications. Analysis of the structural system was carried out using Extended Three-dimensional Analysis of Building System (ETABS) software; where the forces, maximum floor drifts and stresses are obtained and compared. The result shows that, the displacement fora 15 storey building with shear wall was 91.44% less than same without shear walls while with increasing storey height, the differences reduce; for example, the displacement for 20 storey building with shear wall showed 81.5% lesser than same building without shear wall. This signifies that building with shear wall resist aerodynamic load more efficiently principally due to the influences of the rigidity and strategic locations of t...

In recent times, there have been rapid changes in the Architectural design of multi-story buildings tending towards slenderer structures due purposely to space utilization. These changes are not without some inherent challenges on the serviceability requirements of these buildings; of major concern are deflection, oscillation, and excessive vibration developed by the action of wind on the structural members. This study carried out an evaluation of shear wall and frame network subjected to aerodynamic wind load on a 60m, 20 storeys regular building model for aerodynamic resistance of multi-story building with a view to having further improvement on the serviceability criteria. Wind load assessment was carried out in accordance with recommendations of Euro code using critical wind speed of Maiduguri (47m/s) as primary data. Analysis of the structural system was carried out by using approximate rapid manual method and standard software package. An improved equation was developed for deflection from the result of the analysis which satisfies the limiting criteria of the code. Results obtain from the improved equation when compared with the existing limiting criteria shows more flexural rigidity up to about 95% of the height of the building. This means that the improved equation will provide less deflection than the existing method up to 95% of the building, thereby providing more comfort to the occupants of the buildings.

Aging reinforced concrete (RC) building structures typically experience more severe damage and are prone to collapse during earthquakes, constituting a primary factor in casualties and direct economic losses. To enhance the seismic performance of these old structures, this paper proposes a seismic risk assessment and a micro-concrete restoration method. It applies the process to an existing three-story reinforced concrete structure. A practical framework for mitigating structural vulnerabilities in seismic-prone regions was proposed. Then an as-built survey was conducted to create as-built architectural and structural drawings. Concrete core tests, ferroscans, and rebar tests were also performed. Based on field surveys and test data, nonlinear static and dynamic analyses have been used to evaluate structural safety. Concrete column jacketing was used to strengthen weak existing columns with micro-concrete. In assessing the structural response of retrofitted buildings, a comparison was made to their initial state. The comparison shows that applying concrete column jacketing with micro concrete can reduce other structural elements' demand capacity ratio (DCR), minimize maximum displacements, and enhance overall stiffness. The results indicate that the proposed method effectively evaluates the seismic risk of aging structures and enhances seismic resilience in existing buildings. Moreover, the application to the actual structure demonstrates that micro-concrete is highly durable and compatible with parent-concrete.

With the rapid development of new materials and structural techniques, many new kinds of spatial structural systems have been widely used for large-span roofs, such as the sport, exhibition and entertainment halls, and they are becoming more and more large-span and flexible. However, up to now, wind-resistant design of large-span spatial structures is still complex and difficult in practice due to their strong individuality and complexity of architectural shapes and lack of practical and feasible provisions in related codes for structural design especially. In this paper, a practical wind-resistant approach based on Wind-induced Envelope Responses, i.e., the maximum or minimum responses, including displacement of any nodes, internal forces (axial force, bending moment, torsional moment, or extreme stress, etc.) of any elements, reaction of any supports, etc., of the structures in question under the expected wind load action with any attack angle, is presented for this problem from the structural designers' point of view, and the advantages and disadvantages of the existing approaches used in wind-resistant design of large-span spatial structures, as well as the presented one, are analyzed at different aspects, such as necessary information of wind load, time consuming problem, convenience in practice, and so on. Finally, the convenience and efficiency of the presented approach is illuminated with two numerical examples of single layered reticulated shells based on the pressure information obtained from wind tunnel tests.

This report provides an overview of the tornado impact on the safe operation and shutdown of nuclear power plants in the United States. The motivation for this review stems from the damage and failure of the Fukushima nuclear power plant on March 11, 2011. That disaster warrants comparison of the safety measures in place within the global nuclear power industry. key words: tornado damage, nuclear facilities, United States 1. BACKGROUND Nuclear power generation produces 13.5% of the electricity generated worldwide 2) . Approximately 20 % of the electricity produced in the U.S. is provided 99 active nuclear reactors 3) . In 2014 they produced 798 TWh of electricity, accounting for 30% of all the nuclear power produced worldwide, and making the United States (US) the largest producer of nuclear energy 3) . Commercial nuclear energy production began in US in 1957 with the commissioning of the first nuclear reactor in Shippingport, PA. After some growth since that time, development of new nuclear power plants has slowed, to the point where few nuclear reactors have been constructed in US over the past thirty years, due to public apprehension regarding safety concerns and the risk of nuclear contamination of regions around the plants. The most newly commissioned nuclear power plant was the Watts Bar Plant in Tennessee in 1996 4) . Two new reactors began construction in 2013 at the Virgil C. Summer Nuclear Generating Station in South Carolina and the Vogtle Electric Generating Plant in Georgia. Heightened skepticism of nuclear power generation from the public followed the high profile accidents at the Three Mile Island Nuclear Plant in U.S. and the meltdown failure and subsequent closure of the Russian Chernobyl Nuclear Plant. Many of the currently active nuclear reactors in US will be decommissioned over the next 20 years, taking as much as one fifth of the United States nuclear power production offline over that period. The World Nuclear Association reports that thirteen nuclear

This paper describes an along-wind vibration of frame-type pylons of Hakucho Suspension Bridge found from longterm vibration monitoring data. It is shown that the vibration is very harmonic although its amplitude is small and it occurs under certain ranges of wind direction (10~30 degree from the bridge perpendicular axis) and of wind velocity (13~25 m/s). The dominant frequency of the vibration is either 0.6 Hz or 0.8 Hz depending on the wind velocity and these correspond to the natural frequencies of the in-plane pylon dominant modes of the suspension bridge. A series of the wind tunnel experiments using a spring-supported scaled model are conducted under uniform flow and the alongwind pylon vibration was observed and its vibration characteristics is found to be consistent to those observed in Hakucho Bridge. It is also found that the vibration is very sensitive to the incident angle of wind and to the distance between the two columns.

A comprehensive computational and experimental study has been performed at the NASA Langley Research Center as part of the Quiet Aircraft Technology (QAT) Program to investigate the unsteady flow near a leading-edge slat of a two-dimensional, high-lift system. This paper focuses on the experimental effort conducted in the NASA Langley Basic Aerodynamics Research Tunnel (BART) where Particle Image Velocimetry (PIV) data was acquired in the slat cove and at the slat trailing edge of a three-element, high-lift model at 4, 6, and 8 degrees angle of attack and a freestream Mach Number of 0.17. Instantaneous velocities obtained from PIV images are used to obtain mean and fluctuating components of velocity and vorticity. The data show the recirculation in the cove, reattachment of the shear layer on the slat lower surface, and discrete vortical structures within the shear layer emanating from the slat cusp and slat trailing edge. Detailed measurements are used to examine the shear layer formation at the slat cusp, vortex shedding at the slat trailing edge, and convection of vortical structures through the slat gap. Selected results are discussed and compared with unsteady, Reynolds-Averaged Navier-Stokes (URANS) computations for the same configuration in a companion paper by Khorrami, Choudhari, and Jenkins (2004). The experimental dataset provides essential flow-field information for the validation of near-field inputs to noise prediction tools.

In India, reinforced concrete structures are most widely used for construction as it is most convenient and economical system. Rcc is great for low rise structures but as height of structure increases such type of structures doesn't suffice economy due to increased dead load, unsubstantial stiffness and complex formwork. So, for this efficient and economical design solution is need of time. Steel concrete composite construction has gained wide acceptance worldwide as an alternative to pure steel and concrete construction. The High-rise structures of RCC are more bulky and less ductile as compared to composite structures. The use of steel in construction industry is very low in India compared to many developing countries. Composite construction combines the positive properties of both steel and concrete along with speedy construction, fire protection etc. The objective of present research work is to determine the changes caused in building due to variation in the storey height, due to change in seismic zone, to find the effect of wind and seismic loading on the building and to compare the cost estimations of both buildings. All (G+10, G+20, G+30 and G+40) buildings are designed and analysed in Etabs software. Result is compared to find the best among the Rcc and Composite buildings. It is found that composite buildings are better than Rcc building but Rcc buildings are more economical.

Heavy vehicles exiting (or entering) a tunnel at high speed under a strong crosswind is a particularly critical condition since the aerodynamic load changes drastically, greatly affecting the lateral stability of the vehicle. Often, active control systems (active suspensions, active front steering, etc.) and infrastructure elements (e.g., wind fences) are proposed to reduce the induced risks. To help the design of these devices, the present paper investigates the response of the vehicle–driver system in the case of a high-sided lorry exiting a tunnel under crosswind, by using Driver-In-the-Loop simulations. The study was performed using the dynamic driving simulator of Politecnico di Milano and 28 test drivers. Vehicle and aerodynamic models have been developed to reproduce the phenomenon in a highly immersive environment. During the tests, several combinations of vehicle and wind speed were considered. The effect of vehicle loading condition (Empty and Laden) was also investigated....

Residential wood-framed construction failures account for the majority of economic losses following hurricanes. A common failure in these constructions during high wind events is loss of roof sheathing, especially in corner areas. Less common perhaps, but usually catastrophic, is the failure of the roof-to-wall connections in these structures. The main objective of the current research project is to evaluate the in-situ capacity of roof-to-wall connections and sheathing to rafter fasteners in light-framed wood constructions. The unique opportunity provided by Clemson University to access four residential structures located within a residential complex enabled the collection of perishable yet statistically significant data on the strengths of existing residential structures. The uplift capacities of 100 roof-to-wall toenail connections and 34 plank sheathing units were evaluated from field and laboratory tests. Realizing the key role of probability distributions in developing fragility estimates and loss prediction models, distribution fits and parameters for these structural components are postulated. One conclusion drawn is that the uplift capacities of two and three nail connections are best described by a lognormal distribution. The initial stiffness and the vertical displacement at peak load of both two nail and three nail connections follow a normal and Weibull distribution respectively. The uplift capacity of plank sheathing follows a lognormal distribution. An analytical model designed to approximate the uplift behavior of toenail connections is developed to facilitate modeling of roof systems. These probabilistic and analytical models developed by this study allow for the performance of detailed reliability based studies on light-framed wood roof structures.

Small wind turbine power generation systems have the potential to meet the electricity demand of the residential sector in developing countries. However, due to their exposure to low Reynolds number (Re) flow conditions and associated problems, specific airfoils are required for the design of their blades. In this research, XFOIL was used to develop and test three high performance airfoils (EYO7-8, EYO8-8, and EYO9-8) for small wind turbine application. The airfoils were subsequently used in conjunction with Blade Element Momentum Theory to develop and test 3-bladed 6 m diameter wind turbine rotors. The aerodynamic performance parameters of the airfoils tested were lift, drag, lift-to-drag ratio, and stall angle. At Re=300,000, EYO7-8, EYO8-8, and EYO9-8 had maximum lift-to-drag ratios of 134, 131, and 127, respectively, and maximum lift coefficients of 1.77, 1.81, and 1.81, respectively. The stall angles were 12° for EYO7-8, 14° for EYO8-8, and 15° for EYO9-8. Together, the new air...

The exploitation of energy potential of the surrounding ocean and seas is a primary goal of the European Union. The Europe 2016 cumulative power is equal to 12,631 MW from 3589 grid-connected wind turbines in 10 countries. With average new installations of 3.1 GW/year, offshore wind will represent about one-quarter of the total new installations. Most of the installations are bottom-fixed offshore wind (BFOW): 80% monopiles, 9.1% gravity foundations, 5.4% jackets, 3.6% tripods, and 1.7% tripiles, with the average water depth of 27.1 m and the average distance to shore of 43.3 km. Floating offshore wind (FOW) is complimentary to BFOW and holds the key to an inexhaustible resource potential in Europe as 80% of all the offshore wind resource is located in waters 60 m and deeper, where traditional BFOW is not economically attractive. On the contrary, FOW technology, previously confined to R&D, has developed significantly in recent years, and it is now ready to be integrated into the energy market. Europe will take advantage of technologies and cost reduction techniques developed in BFOW. There are currently four substructure designs for FOW: barge, semisubmersible, spar buoy, and tension leg platform (TLP). The first three are loosely moored to the seabed, allowing for easier installation, while the TLP is more firmly connected to the seabed assuring more stable structure. The technology readiness level (TRL) related to semi-submersible and spar buoy substructures has entered a phase (>8) with technology appropriate for launch and operations. The barge concept could reach this stage in the coming years, while the TLP could be closer to exploitation. At present, Mediterranean countries, except France, have had a reduced R&D and demonstration planning on offshore wind because of lower wind regimes, high coastal water depth and claimed ambient, social impact (tourism, fishing, etc.). However, experts of France, Greece, Italy, and Spain have shown that optimized FOW system with lower but regular wind and wave regime could exploit a significant potential. The OWEMES Association (www.owemes.org), founded in 2006, has been the active promotion body for marine renewable energies in the south Europe. The main aim is to diffuse the international research, technology, financial, and market results in the Mediterranean area to promote applications and foster R&D and industry to enter in these promising sectors. Such promotion analysis is carried out through organizing triennial and at present biennial technical events as the European Seminar OWEMES 2017 (www.owemes-2017.eu), held in Bari, Italy, 11-13 October 2017. The Conference was held in the Politecnico di Bari with the scientific support of Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma and the infrastructural support of Aires Tech Srl. The event was sponsored by Italian Minister of Environment, ATENA Association, Club per l'UNESCO Bari, and Qualenergia Magazine acted as media partner. The specific goal of OWEMES 2017 was to present the state of art in Europe on offshore wind and ocean energies, the R&D activity, and demonstration projects in the Mediterranean area. More than 35 papers, from several countries in Europe, were presented, giving a wide overview over the new trends and technological perspectives for Marine Energies in Mediterranean Sea. During a Round Table, experts, researcher, and stakeholders were stimulated to indicate new actions to be promoted in Italy and in the South European countries for developing the Marine Energy sector. The main outcomes were disseminated at National and European Level. This special issue of Wind Engineering contains a selection of papers presented at OWEMES 2017 and focused on Offshore Wind Engineering. Numerical and experimental studies on producibility, wear problems due to aggressive environment, mooring design, controls, and testing are presented and discussed in this Special Issue. The editors believe that this publication will serve as a valuable resource to stimulate the discussion about FOW applications for Mediterranean Sea in the Scientific Community, as well as to inspire new advancement in the field of development of innovative floating platform concepts or wind turbine.

The exploitation of energy potential of the surrounding ocean and seas is a primary goal of the European Union. The Europe 2016 cumulative power is equal to 12,631 MW from 3589 grid-connected wind turbines in 10 countries. With average new installations of 3.1 GW/year, offshore wind will represent about one-quarter of the total new installations. Most of the installations are bottom-fixed offshore wind (BFOW): 80% monopiles, 9.1% gravity foundations, 5.4% jackets, 3.6% tripods, and 1.7% tripiles, with the average water depth of 27.1 m and the average distance to shore of 43.3 km. Floating offshore wind (FOW) is complimentary to BFOW and holds the key to an inexhaustible resource potential in Europe as 80% of all the offshore wind resource is located in waters 60 m and deeper, where traditional BFOW is not economically attractive. On the contrary, FOW technology, previously confined to R&D, has developed significantly in recent years, and it is now ready to be integrated into the energy market. Europe will take advantage of technologies and cost reduction techniques developed in BFOW. There are currently four substructure designs for FOW: barge, semisubmersible, spar buoy, and tension leg platform (TLP). The first three are loosely moored to the seabed, allowing for easier installation, while the TLP is more firmly connected to the seabed assuring more stable structure. The technology readiness level (TRL) related to semi-submersible and spar buoy substructures has entered a phase (>8) with technology appropriate for launch and operations. The barge concept could reach this stage in the coming years, while the TLP could be closer to exploitation. At present, Mediterranean countries, except France, have had a reduced R&D and demonstration planning on offshore wind because of lower wind regimes, high coastal water depth and claimed ambient, social impact (tourism, fishing, etc.). However, experts of France, Greece, Italy, and Spain have shown that optimized FOW system with lower but regular wind and wave regime could exploit a significant potential. The OWEMES Association (www.owemes.org), founded in 2006, has been the active promotion body for marine renewable energies in the south Europe. The main aim is to diffuse the international research, technology, financial, and market results in the Mediterranean area to promote applications and foster R&D and industry to enter in these promising sectors. Such promotion analysis is carried out through organizing triennial and at present biennial technical events as the European Seminar OWEMES 2017 (www.owemes-2017.eu), held in Bari, Italy, 11-13 October 2017. The Conference was held in the Politecnico di Bari with the scientific support of Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma and the infrastructural support of Aires Tech Srl. The event was sponsored by Italian Minister of Environment, ATENA Association, Club per l'UNESCO Bari, and Qualenergia Magazine acted as media partner. The specific goal of OWEMES 2017 was to present the state of art in Europe on offshore wind and ocean energies, the R&D activity, and demonstration projects in the Mediterranean area. More than 35 papers, from several countries in Europe, were presented, giving a wide overview over the new trends and technological perspectives for Marine Energies in Mediterranean Sea. During a Round Table, experts, researcher, and stakeholders were stimulated to indicate new actions to be promoted in Italy and in the South European countries for developing the Marine Energy sector. The main outcomes were disseminated at National and European Level. This special issue of Wind Engineering contains a selection of papers presented at OWEMES 2017 and focused on Offshore Wind Engineering. Numerical and experimental studies on producibility, wear problems due to aggressive environment, mooring design, controls, and testing are presented and discussed in this Special Issue. The editors believe that this publication will serve as a valuable resource to stimulate the discussion about FOW applications for Mediterranean Sea in the Scientific Community, as well as to inspire new advancement in the field of development of innovative floating platform concepts or wind turbine.

Wind-induced loss modeling plays a key role in insurance risk management. Hence, a flexible vulnerability framework is to be developed for residential and commercial buildings. This model predicts the losses induced by hurricane wind pressure, wind-borne debris and wind-driven rain. Twenty-five different key variables of the buildings and environment are used as attributes for the simulations. Model results are validated using the Florida Public Hurricane Loss Models (FPHLM) and HAZUS wind vulnerability functions. New contributions include (1) a Markovian roof-aging model to address decreases in roof performance due to aging, and (2) occupancy-specific interior value models based on FEMA Normative quantities for the systematic evaluation of interior value applicable to archetype buildings. A simple wind debris impact model and wind-driven rain intrusion model is also introduced. The influence of the number of stories, roof aging, and window vulnerability resulting in damage are inve...

: izr. prof. dr. Boštjan Brank (UL) Somentor: prof. dr. Werner Guggenberger (TU Graz) Naslov: Analiza in projektiranje tankostenskih cilindričnih silosov v skladu z Evrokod standardi Obseg in oprema: 372 str., 50 pregl. (slo.), 71 sl. (slo.), 461 en. (slo.), 28 pregl. (ang.), 52 sl. (ang.), 247 en. (ang.) Ključne besede: cilindrični silosi, obtežba, analiza, projektiranje, Evrokod Izvleček Diplomska naloga je zamišljena kot priročnik za analizo in projektiranje tankostenskih, cilindričnih, osno simetričnih metalnih silosov v skladu z Evrokod standardi. Vsebinsko je razdeljena na tri dele. V prvem delu so obravnavane vse pomembnejše obtežbe, ki delujejo na silose. Poseben poudarek je namenjen obtežbam, ki nastanejo pri polnjenju in praznjenju ter obtežbe zaradi vetra in potresa. Za vsako od teh obtežb je na enostaven in razumljiv način (po korakih in v obliki diagramov poteka) podan postopek za izračun pritiskov po silosu. Izpeljani so izrazi za membranske sile. Pri obtežbah zaradi polnjenja in praznjenja so bistveni izrazi grafično prikazani v posplošeni (brezdimenzijski) obliki, s čimer postanejo bolj pregledni in hitro berljivi za različne geometrije silosov in za različne shranjene materiale. Raziskane so nekatere nejasnosti, ki se pojavljajo v standardih. Predstavljene so obtežne kombinacije, ki jih je potrebno upoštevati pri projektiranju. V drugem delu diplomske naloge je izračunan praktični računski primer z upoštevanjem postopkov iz prvega dela. V tretjem delu sta predstavljena dva računalniška programa, ki sta tudi bila izdelana v sklopu te naloge. Prvi je namenjen določitvi obtežbe shranjenega materiala na stene silosa, drugi pa določitvi obtežbe vetra na stene silosa. Programa sta na zgoščenki, ki je priložena nalogi. V prilogah sta tudi angleška prevoda prvega in tretjega dela.

Recent observations published by Buckley et al. (2025) in Nature Communications have revealed direct evidence of two distinct wind-wave coupling mechanisms at the ocean-atmosphere boundary: sheltering-induced separation in short, wind-forced waves, and orbital-induced airflow entrainment in longer, fast-traveling swells. These insights validate core theoretical expectations of the Fractal Theory (Morgan M. D. 2025a), which posits that all energetic interactions can be understood through the recursive action of Unity, Division, and Scale. This white paper offers a Fractal Theory-aligned commentary on these findings and introduces a scalar-shell-based explanation for the observed coupling modes.

The dynamics of an overhead crane system with the suspended payload on the trolley moving at a specified constant speed is considered in this paper. The beam is discretizied by 10 elements, while the trolley is modeled as particle along with payload suspended with rope system modeled as spring. The overall mass, damping and stiffness matrix is calculated at each time interval, along with finite element formulation of equivalent force vector. Equations of motion of MDOF system are given for oscillator moving on beam structure. Dynamic responses in the vertical direction for all DOFS are obtained by solving the governing equations with direct integration method. For validation purposes, the technique is first applied to a simple beam subjected to a force moving along the beam with constant velocity. The influence of moving velocity and spring stiffness are investigated.

The construction of a three-span suspension bridge with two floating pylons is currently being considered for crossing the 5-km-wide and 550-m-deep Bjørnafjorden in Norway. The bridge design represents a novel concept that requires a detailed dynamic analysis to improve the current understanding of its dynamic behavior. Geometric nonlinearities in the cables and mooring system and nonlinearities in the load models are of particular interest; in addition, the relative influence of the buffeting wind forces and the first-and second-order wave excitation forces were carefully studied. The response predictions were obtained using state-of-the-art time domain methods.

Accuracy of velocity-vorticity ( V, ω)-formulations over other formulations in solving Navier-Stokes equation has been established in recent times. However, the issue of non-satisfaction of solenoidality conditions on vorticity is not addressed in the literature which can possibly lead to non-physical solution. In this respect, here, we have developed and reported conservative rotational form of the ( V, ω)-formulation which preserves the solenoidality condition on vorticity in a much simpler way compared to other formulations. Superiority of rotational form over the conventional Laplacian form of ( V, ω)-formulation is also shown [by comparing the results for flows inside cubical lid driven cavity (LDC)]. For solving the 3D Navier-Stokes equation using a staggered grid, we use optimized compact schemes for (a) interpolation and (b) evaluation of first and second derivatives. As illustrations, we have solved problems of (i) flow inside a 3D lid driven cavity (LDC), whose solutions are compared with experimental results reported by Koseff and Street [J. Fluids Engg. 106, 390-398 (1984)] and (ii) 3D

This study presents a novel numerical methodology that is designed for the dynamic adjustment of three-dimensional high-rise building configurations in response to aerodynamic forces. The approach combines two core components: a numerical simulation of fluid flow and the adjoint method. Through a comprehensive sensitivity analysis, the influence of individual variables on aerodynamic loads, including lift and drag coefficients, is assessed. The findings underscore that the architectural design, specifically the building's construction pattern, exerts the most substantial impact on these forces, accounting for a substantial proportion (76%). Consequently, the study extends its evaluation to the sensitivity of fluid flow across various sections of the tower by solving the adjoint equation throughout the entire fluid domain. As a result, the derived sensitivity vector indicates a remarkable reduction of approximately 31% in the applied loads on the tower. This notable improvement has significant implications for the construction of tall buildings, as it effectively mitigates aerodynamic forces, ultimately enhancing the overall comfort and structural stability of these architectural marvels.

Wind tunnel tests of tall buildings are capable of accurately determining the wind loads on a building in its current surroundings, since the surroundings are included in the wind tunnel modelling. The tests may also include some future developments if they are known to be imminent. However, the question of the effects of possible longer term changes in surroundings needs to be considered. In some cases the development of the city may be mature resulting in little likelihood of future changes, but in rapidly developing cities the possible changes may be significant. It is known that buildings very close to the building under test can have significant sheltering effects in some cases and may amplify wind loads in other cases. Cases have been seen where the removal of an important adjacent building more than doubled the wind loads. Wind tunnel testing can readily determine loads in the different scenarios but the question of how to treat the data requires some thought. This paper pres...

CFD calculations of NREL Phase VI rotor under wide range of operation conditions were conducted using FlowVision software. Computations were performed for various wind speeds with axial inflow, constant RPM and constant blade pitch. The rotation of the blades was modeled via different approaches; steady-state with frozen rotor using rotating reference frame and transient with moving boundaries or sliding surfaces. In addition to this, an 'Overlapping Boundary Layer (OBL)' was implemented to resolve the boundary layer for a selected case. Turbulence models 'k-ε-AKN and k-ω Shear Stress Transport (SST) were used and compared. Except the OBL case, FlowVision wall function approximation was employed for all calculations with y+ values between 30 and 100. Overall results were compared for all of the above-mentioned numerical approaches and showed good agreement with the experimental data. k-ω SST turbulence model is found to perform better to predict stall onset. The stall occurrence and general torque trend as a function of wind speed is fairly well captured. Comparisons of the static pressure distribution around blades with experimental data at different span-wise sections for different wind speeds are presented and good agreement is observed.

The forecast of wind ramps is of critical importance for wind power integration and wind plant management. The wind power plants in the Gaspe region of Quebec (Canada) often experience rapid changes in wind speed mainly due to mountain waves and down-slope winds. A Canadian mesoscale model, GEM-LAM, was set-up in Gaspe region at a horizontal resolution of 2.5 km for wind power prediction. Comparison with observations at wind plants revealed that most of the ramps due to mountain waves are correctly predicted in terms of amplitude and timing of the events by the mesoscale model. Forecasts from the Canadian Meteorological Center's operational weather prediction model at lower horizontal resolution (15 km) largely under-predicted the amplitude of wind ramps. A forecast index based on the Froude Number was developed to diagnose the onset of mountain waves. It was found that the forecast index is very useful for detecting the wind ramps due to mountain waves, particularly for those w...

This paper explores the pedagogical context for the inclusion of daylight and wind simulation as part of architectural design-studio teaching. The author describes both challenges as well as opportunities encountered by architecture students who applied high-end technology for optimizing environmental conditions during the conceptual design of a residential project within a thirteen week studio. Students located their projects in an inner urban context in a 'Temperate' climate zone, meaning that they had to account for hot conditions in summer while considering wind-chill factors in winter. Based on the studio experience, the paper scrutinizes how students tackled Computational Fluid Dynamics (CFD) and daylight analysis on different scales of their project. The paper explores how the engagement with latest tools available to architecture students changes their ability to discuss building physics with engineers and question precedence typology. The author describes the pedagogical challenges when helping architecture students to overcome obstacles in communicating engineering aspects inherent to the design process.

Most of the current design methodologies for ducted wind-turbines rely on an uncoupled design-procedure of the duct and the rotor. The aim of this work is to assess, for the first time, the reliability of this strategy by quantifying the differences with an advanced fully-coupled approach. Therefore, two different aero-designs are performed using these strategies. In the uncoupled approach the duct geometry is optimized to maximize the ingested mass flow rate disregarding the rotor presence. Then, a free-vortex disk is introduced, and its load is varied to maximize the power coefficient based on the device frontal-area (𝐶 𝑃 ,𝑒𝑥). In the coupled design, the duct geometry and the rotor load are simultaneously optimized. In both cases, the CFD-actuator-disk is used as analysis method along with a gradient-based optimizer. The coupled strategy yields a higher 𝐶 𝑃 ,𝑒𝑥 (0.68) adopting a compact diffuser and high stagger-angle. Contrarily, the uncoupled procedure leads to a lower 𝐶 𝑃 ,𝑒𝑥 (0.59) using a large chord and a moderate stagger. A physical explanation of these differences is offered. Finally, while the presented cases refer to a given shape of the duct, the conceptual generality of the study in terms of the effective reliability of the uncoupled design remains valid in general.

According to the Betz-Joukowsky limit, the maximum power coefficient of a wind turbine is 16∕27. This limit is obtained assuming a priori that the disk is radially uniformly-loaded. In other words, the proof of the limit does not evaluate the optimum type of the load distribution, but it directly speculates that radially uniform load is the optimal one. Therefore, it should be questioned if a radially varying load with a power coefficient higher than 16∕27 exists, which overrules the Betz-Joukowsky limit. For this reason, the paper presents, for the first time, an original numerical optimisation strategy aimed at proving, with a prescribed accuracy level, the validity of the Betz-Joukowsky limit, i.e., at verifying whether or not the optimal load distribution is uniform. The proposed strategy combines a Computational-Fluid-Dynamic-Actuator-Disk model with a classical gradient-based optimisation algorithm. The former aims at computing the objective function (i.e., the power coefficient), whereas the latter is devoted to the detection of the optimum. The procedure assumes that the load distribution is a real analytic function, while the optimisation variables are the coefficients of its Taylor polynomial. The proposed methodology is thoroughly verified, and its overall accuracy level is quantified. Up to an 8th-degree Taylor polynomial, the outcome of the numerical optimisation procedure differs from the Betz-Joukowsky solution by a quantity equal to the uncertainty of the adopted computational strategy. In other words, within the given accuracy range, the analysis confirms the validity of the Betz-Joukowsky limit based on the radially uniform load. Finally, it should be stressed that if the actual optimum differed from the Betz-Joukowsky limit by an amount less than the accuracy of the adopted numerical method, then that optimum could not be detected by the proposed procedure.

Due to their potential to enhance power output, potentially even exceeding the Betz-Joukowsky limit, diffuseraugmented wind turbines are gaining interest, especially for small-scale applications. However, the lack of fast and reliable analysis methods tailored to these devices still hinders their widespread adoption. This paper applies, for the first time, a coupled actuator-disk/Blade-Element-Theory model, embedded in a Computational Fluid Dynamics code, to the analysis of diffuser-augmented wind turbines, and includes a thorough validation of the proposed approach. The flow field is obtained through a Reynolds-Averaged Navier-Stokes solver, while turbine effects are modelled via body forces iteratively evaluated using a Blade-Element scheme. An additional original aspect is that porting this methodology from open to ducted rotors requires a tip-correction-factor model specifically adapted to account for rotor-duct interactions near the blade tips. The results are validated in terms of global performance coefficients using available experimental data. For two turbines, local flow quantities, including wake velocities, are successfully compared with data from a more advanced blade-resolved Reynolds-Averaged Navier-Stokes solver. A relevant new finding is that, contrary to expectations, the actuator disk approach accurately predicts the pressure recovery in the duct divergent part, where strong interactions between the duct boundary layer and tip vortices take place. A further new result is that, for small tip gaps, the blade-forces near the tip exhibit a decreasing-increasing-decreasing trend, associated with tip-vortex/duct interaction. This behaviour cannot be reproduced by simply adapting conventional models for open rotors, thus highlighting the need for a dedicated correction strategy.

This paper presents evaluation of a 67.12m high telecommunication tower with the objectives of applying the Finite Element Method (FEM) in modelling it, analysing it under Nigerian wind loads from five different wind zones (Zone 1, Zone 2, Zone 3 Zone 4 and Zone 5 with basic wind speeds as 42m/s, 45.8m/s, 50m/s, 55m/s and 56m/s respectively). The collapse mechanism of the tower was predicted using the Mechanism Method. The tower was modelled and wind load was calculated on it and analysis shows that there is  mechanism for the tower to collapse under dynamic wind loads as plastic hinges are developed at the joints and along bracing  members. The most severe wind load was used in the plastic analysis conducted and it shows that when the plastic hinges developed at the lower section of the tower, the three mechanisms are more critical compared to when it develops at other sections of the tower. Also, using such load as the collapse load, when the plastic hinges developed at any sectio...

The increasing relevance of offshore wind in the energy mix motivates continual research efforts for the optimisation of foundation systems. Currently, monopiles are still the most common foundations for offshore wind turbines (OWTs), due to their simplicity and the low costs for production/assembly. However, the modern trends towards larger OWTs and water depths pose new geotechnical challenges in the design of more cumbersome and expensive monopiles. In this work, the potential of 3D finite element (FE) modelling for OWT applications is illustrated. The dynamic response of a soil-monopile-OWT system is numerically simulated by accounting for (i) dynamic hydro-mechanical (HM) coupling in the soil and (ii) cyclic plasticity modelling. In particular, the UCSD08 sand model developed by Yang and Elgamal (2008) has been adopted and calibrated against laboratory test results on medium dense sand. FE results are presented to highlight the combined influence of wind/wave loading and soil n...

Basically, cooling tower is a devise which extract waste heat from industry or plant building to the atmospherethrough cooling of water stream at a lower temperature. As these are very huge thin shell structures, they basically subjected toits selfweight and the dynamic loads as an earthquake load and wind load. Recent devastative occurred earthquakes havevulnerable effects on cooling towers and played vital role of them in safety and performance of power plants during and after astrong ground motion. The cooling tower has been analyzed for the wind load as well as the seismic load by using the finiteelement analysis of ANSYS version by assuming its bottom end fixed and top end free to displace. As a part of analysis, coolingtower of height 143.50 mt is taken of having different column supporting systems i.e. H-frame, V-frame, I-frame, A-frame. Theeffect of wind load on the cooling tower is considered by defining design wind pressure coefficients given in IS: 11504-1985 alongwith the pressure distribution at various height as per given in IS: 875-PartIII-1987. Seismic load is carried out by applying 0.5gin accordance with the IS: 1893-2016. For the purpose of comparison, maximum principle stresses, shear stresses anddeformation of tower are derived from the analysis.

ABSTRACT: Wind environment in low zone above two types of cross sections, of a long trans-oceanic bridge, with different types of guardrails and wind barriers is investigated, by numerical simulation based on Random Vortex Method (RVM). It is found that when the ...

Ventilation in an enclosed space can significantly influence people’s comfort, health, and safety. Poor ventilation can generate temperatures dangerous to health or obstruct the dispersion of environmental pollutants, such as toxic gases or pollution. Measuring indoor environmental conditions can thus help improve the quality of the environment and protect people’s health and comfort. This work proposes the design of an open-source anemometer to measure wind speed and direction in three dimensions. The purpose of this anemometer is to monitor wind conditions in enclosed spaces and environmental conditions related to air quality and temperature. The prototype uses an array of six unidirectional flow sensors, each pointing towards a different axis. Carbon dioxide (CO
), volatile organic compounds (VOC), temperature, humidity, pressure, and gas presence sensors are integrated to monitor indoor environmental conditions accurately. Measuring the vertical component of the wind provides more detailed information on wind conditions. Test results show that the device can detect variations in wind speed with a deviation of 0.25 m/s, detect changes in horizontal wind direction with a deviation of 3.7°, and detect vertical wind direction variations with a deviation of 3.02°. These measurements demonstrate that the proposed device is capable of detecting wind changes in three dimensions, validating its potential for detailed indoor airflow monitoring.

In this study, flutter frequency of two joined cantilever beams used for energy harvesting has been investigated and optimized. Since there is a strong connection between the output power of the harvester and the system flutter frequency, maximizing flutter frequency increases the output energy significantly. The governing equations are developed using Euler-Bernoulli beam theory, and series method as an analytical approach is used for the solution. The obtained results were compared with the previous investigations, and effects of change in geometrical parameters are studied. The maximum flutter frequency is obtained using shape optimization for the tail beam. It is concluded that the optimized shape of the tail beam with constant length and volume causes significant increase in the flutter frequency, which improves the output power.

This paper aims to show a refurbishment project of an off-shore wind turbine, combining its natural purpose of exploiting the wind resources in the windiest sea areas along the coasts of Italy (Sardinia, Sicily, Abruzzo, Apulia) together with the possibility of using its structure as a tourist accommodation. Therefore, the main purpose of the paper is not to evaluate the wind turbine fluid dynamic response, but to study the interaction between civil architecture and mechanical structure. In this way, an economical contribution to the sustainability of the wind farm is possible. On this basis, a floating wind turbine called ARYA, has been designed as case-study. First of all, the 2 tourist-receptive structures (Hotel and bar-restaurant) around the wind tower have been designed and checked. Later, in order to study the effects on vertical cables fixed to the sea bottom, a detailed analysis of the floating anchorage TLP (Tension Leg Platform) was carried out. TLP consists of a nearly fully submerged cylindrical platform, which supports a 5 MW wind turbine and is linked to the sea bottom by 3 ties which assure stability and limited tilting, even under the worst loads induced by wind and sea. Morison's equation is used to compute the hydrodynamic loading on the TLPs. A numerical model has been implemented and nonlinear dynamic analysis have been performed, investigating both the wind-structure and the wave-structure interaction. The analysis was based on the extreme environmental conditions of the site where it has been suggested to install the system.

The partners in the ENDOW (Efficient Development of Offshore Windfarms) project are validating, testing, designing and improving wind farm design tools for the efficient design of offshore wind farms. The different meteorological conditions offshore constitute a challenge for the current design tools and models because they have been developed and tested primarily for the design of land based wind farms. Measured downwind of turbines, wake-affected wind speed profiles at Vindeby offshore wind farm have been compared with the model predictions for single, double and quintuple wake cases. The modelling groups have based on these results adjusted their wake models for offshore wind farm design. This paper presents the data, model comparisons and the improvements to the models.