Finite element methods in wind engineering

One of the fundamental problems in simulating the motion of sharp interfaces between immiscible fluids is a description of the transition that occurs when the interfaces merge and reconnect. It is well known that classical methods involving sharp interfaces fail to describe this type of phenomena. Following some previous work in this area, we suggest a physically motivated regularization of the Euler equations which allows topological transitions to occur smoothly. In this model, the sharp interface is replaced by a narrow transition layer across which the fluids may mix. The model describes a flow of a binary mixture, and the internal structure of the interface is determined by both diffusion and motion. An advantage of our regularization is that it automatically yields a continuous description of surface tension, which can play an important role in topological transitions. An additional scalar field is introduced to describe the concentration of one of the fluid components and the resulting system of equations couples the Euler (or Navier–Stokes) and the Cahn–Hilliard equations. The model takes into account weak non–locality (dispersion) associated with an internal length scale and localized dissipation due to mixing. The non–locality introduces a dimensional surface energy; dissipation is added to handle the loss of regularity of solutions to the sharp interface equations and to provide a mechanism for topological changes. In particular, we study a non–trivial limit when both components are incompressible, the pressure is kinematic but the velocity field is non–solenoidal (quasi–incompressibility). To demonstrate the effects of quasi–incompressibility, we analyse the linear stage of spinodal decomposition in one dimension. We show that when the densities of the fluids are not perfectly matched, the evolution of the concentration field causes fluid motion even if the fluids are inviscid. In the limit of infinitely thin and well–separated interfacial layers, an appropriately scaled quasi–incompressible Euler–Cahn–Hilliard system converges to the classical sharp interface model. In order to investigate the behaviour of the model outside the range of parameters where the sharp interface approximation is sufficient, we consider a simple example of a change of topology and show that the model permits the transition to occur without an associated singularity.

In general, the study of a high-rise building’s behaviour when subjected to a horizontal load (wind or earthquake) is carried out through numerical modelling with finite elements method. This paper proposes a new, original approach based on the use of a multi-beams model. By redistributing bending and axial stiffness of horizontal elements (beams and slabs) along vertical elements, it becomes possible to produce a system of differential equations able to represent the structural behaviour of the whole building. In this paper this approach is applied to the study of bending behaviour in a 37-storey building (Torre Pontina, Latina, Italy) with a regular reinforced concrete structure. The load considered is the wind, estimated in accordance with Italian national technical rules and regulations. To simplify the explanation of the approach, the wind load was considered uniform on the height of building with a value equal to the average value of the wind load distribution. The system of differential equations’ is assessed numerically, using Matlab, and compared with the obtainable solution from a finite elements model along with the obtainable solutions via classical Euler-Bernoulli beam theory. The comparison carried out demonstrates, in the case study examined, an excellent approximation of structural behaviour.

The article is devoted to calculation of three-dimensional magnetostatic fields of electrical engineering devices of fixed or with linear motion trajectory of various functional purposes by the finite element method using a regular finite element network. The aim of the research is to create an algorithm for forming coefficients of global SLAE of the finite element method on the basis of three-dimensional finite element hyper-cube when solving magnetostatic problems for obtaining engineering methods. The study subject is magnetostatic three-dimensional vector models of electromagnetic processes of electrical engineering devices, electrical engineering and electromechanical systems and methods of their calculation. The tasks are: to develop three-dimensional elements such as cube and hyper-cube, to obtain recurrent relations for global system of linear algebraic equations (SLAE) coefficients. Research methods are: numerical calculations based on projection-grid method of the Galerkin in combination with the finite element method. The results are: a three-dimensional element of cube and hyper-cub type for a three-dimensional regular network of the finite element method has been offered, and recurrence relations for global SLAE coefficients are developed when working out engineering methods for calculating magnetostatic fields and their power characteristics in electrical engineering devices with minimal costs of the computer dynamic memory.

The paper summarizes recent research and development of computer-aided and computational methods in wind engineering at the National Institute of Standards and Technology (NIST). Specific topics to be covered include: 1. Time-domain database-assisted design of tall, flexible structures excited by turbulent winds inducing dynamic structural responses. 2. Computational Fluid Dynamics (CFD) estimates of aerodynamic pressure on low-rise buildings with geometrical dimensions comparable to the across-wind integral turbulence length scale. 3. Development of synthetic directional wind speed databases covering on the order of 10,000 years, from measured wind speeds over periods of approximately 30 years. 4. Probability distributions of hurricane wind speeds, Gulf and Atlantic coasts. 5. Extreme wind speeds in non-hurricane prone conterminous United States. 6. Estimates of hurricane-borne missile speeds. 7. Disaster and Failure Events Repository - a new research tool for archival and analysis of post-disaster information and data.

The research paper focuses on internal forces determination in the elements of modular buildings under wind load. It provides a methodology for determining dynamic characteristics of a building and for calculating wind loads. This method is based on the following assumptions: coupling of the modules elements is rigid; coupling of block-modules with foundations is hinged-fixed; connection of blocks to each other is hinged in angular points; the floor disk in its plane is not deformed. On the basis of these assumptions the authors derived approximate and refined equations for determining forces in modules elements under static and pulsation components of wind load. The equation of bending moments determination in the pillar bearing cross-section is obtained by approximation of the graph of moments variation, calculated for the spectrum of the ratio of the pillar stiffness and the floor beam in the range from 1/64 to 64. The paper further introduces the calculation results of forces based on the proposed methodology and on the finite element method. The calculations were done while taking different values of wind load and different number of storeys in a building (from 1 to 4 floors). The obtained results are similar, the error does not exceed 5%.

Tall buildings are vulnerable to wind loads, which can cause significant displacements that can affect their stability, strength, and serviceability. Their structural configuration can significantly influence their behavior to wind loads. There are not enough comparative studies in the literature examining the effects of wind loads on different structural configurations. This study examines the response of tall buildings to wind loads by varying their structural forms. Twelve models of tall buildings of different heights and structural configurations were analyzed using the finite element method. Wind loads were applied to the models as equivalent static forces, according to existing codes. The maximum displacements were calculated for each model, and the results were compared. It was found that a considerable reduction in the response was achieved by including shear walls at specific locations in the building’s layout, thereby identifying the optimal location. However, the effectiveness of the different configurations converges at building heights greater than 120 m. In addition, the maximum displacement on the same floor in buildings with the same structural form may vary depending on the building’s total height. An increase in wind velocity results in an almost linear increase in the maximum displacements of the buildings. The findings of this study can assist designers in optimizing shear wall placement in tall building designs.

This paper provides a simple numerical method to determine the optimal parameters of tuned mass damper (TMD) and viscoelastic dampers (VEDs) in frame structure for wind vibration control considering the soil-structure interation (SSI) effect in frequency domain. Firstly, the numerical model of frame structure equipped with TMD and VEDs considering SSI effect is established in frequency domain. Then, the genetic algorithm (GA) is applied to obtain the optimal parameters of VEDs and TMD. The optimization process is demonstrated by a 20-storey frame structure supported by pile group for different soil conditions. Two wind resistant systems are considered in the analysis, the Structure-TMD system and the Structure-TMD-VEDs system. The example proves that this method can quickly determine the optimal parameters of energy dissipation devices compared with the traditional finite element method, thus is practically valuable.

The mathematical modelling of deformable, permeable screen doors was explored to assess their behaviour under wind loading. A load-response model was proposed whereby the wind load was modelled using a simplified approach that allowed it to be approximated as a uniformly distributed pressure load with empirical modification factors applied to relate it to the real case of a door on a building. Several approaches were adopted to model the mechanical behaviour of the door system in response to load, including discrete models based on mass-spring systems, continuum models based on the membrane equations (including tension modulation in some cases), and computational models using finite element packages. The primary aim of the work was to determine the distribution of wind load to the door's supporting `tabs' and estimate a failure wind speed. The mass-spring model and the membrane models without tension modulation both generated unrealistic deflection magnitudes in response to wind load, but could be calibrated in future work, and then used to obtain an estimate of the total force on the tabs. A tension-modulated version of the membrane model performed better with regards to deflected shape and magnitude, but time constraints meant that the load on the tabs was not calculated. Preliminary validation experiments were undertaken and deflected shape and magnitude were successfully measured in response to given wind speeds. References Standards Australia. AS/NZS1170.2–-Structural design actions part 2: Wind actions , 2011. F. Avanzini and R. Maronga. A modular physically based approach to the sound synthesis of membrane percussion instruments. IEEE Transactions on Audio, Speech, and Language Processing , 18(4):891–902, 2010. doi:10.1109/TASL.2009.2036903 B. Bank. Energy-based synthesis of tension modulation in strings. In Proceedings of the 12th International Conference on Digital Audio Effects (DAFx-09) , 2009. http://dafx09.como.polimi.it/proceedings/papers/paper_76.pdf Bert Blocken. 50 years of computational wind engineering: Past, present and future. Journal of Wind Engineering and Industrial Aerodynamics , 129(0):69–102, 2014. doi:10.1016/j.jweia.2014.03.008 Demetres Briassoulis, Antonis Mistriotis, and Anastasios Giannoulis. Wind forces on porous elevated panels. Journal of Wind Engineering and Industrial Aerodynamics , 98(12):919–928, 2010. doi:10.1016/j.jweia.2010.09.006 John Cheung and William Melbourne. Wind loading on porous cladding. In 9th Australasian fluid mechanics conference , 1986. http://people.eng.unimelb.edu.au/imarusic/proceedings/9/CheungMelbourne.pdf John Holmes. Wind Loading of Structures . Spon Press, 2001. P. D. Howell, G. Kozyreff, and J. R. Ockendon. Applied Solid Mechanics . Cambridge University Press, 2009. C.W Letchford. Wind loads on rectangular signboards and hoardings. Journal of Wind Engineering and Industrial Aerodynamics , 89(2):135–151, 2001. doi:10.1016/S0167-6105(00)00068-4 Wojciech Okrasinski and \T1\L ukasz Plociniczak. A nonlinear mathematical model of the corneal shape. Nonlinear Analysis: Real World Applications , 13(3):1498–1505, 2012. doi:10.1016/j.nonrwa.2011.11.014 D. W. Oplinger. Frequency response of a nonlienar stretched string. Journal of the Acoustical Society of America , 32(12):1529–1538, 1960. doi:10.1121/1.1907948 Xavier Provot. Deformation constraints in a mass-spring model to describe rigid cloth behaviour. In Graphics interface , pages 147–147. Canadian Information Processing Society, 1995. http://kucg.korea.ac.kr/education/2005/CSCE352/paper/provot95.pdf P.J Richards and M Robinson. Wind loads on porous structures. Journal of Wind Engineering and Industrial Aerodynamics , 83(13):455–465, 1999. doi:10.1016/S0167-6105(99)00093-8 A.P. Robertson, Ph. Roux, J. Gratraud, G. Scarascia, S. Castellano, M. Dufresne de Virel, and P. Palier. Wind pressures on permeably and impermeably-clad structures. Journal of Wind Engineering and Industrial Aerodynamics , 90(45):461–474, 2002. Bluff Body Aerodynamics and Applications. doi:10.1016/S0167-6105(01)00210-0 T. Tolonen, V. Valimaki, and M. Karjalainen. Modeling of tension modulation nonlinearity in plucked strings. IEEE Transactions on Speech and Audio Processing , 8(3):300–310, 2000. doi:10.1109/89.841212

An analytical approach and numerical solution to determine coupled aeroelastic and hydroelastic response of floating offshore wind turbines of arbitrary shape to combined wind and wave loads is presented. The model considers simultaneously the aerodynamic and hydrodynamic loads on an FOWT and integrates these with finite element method for structural analysis due to the combined loads. The hydrodynamic and aerodynamic loads are determined based on the linear wave diffraction theory and steady blade element momentum method, respectively, and the solution is obtained in frequency domain. The structure may be fixed or floating, located in arbitrary water depth, and may host single or multiple wind towers. The model captures the complete translational and rotational motions of the body in three dimensions, and the elasticity of the blades, tower and the floating platform. To assess the performance of the model, rigid and elastic responses of a FOWT to combined wave and wind loads are computed and compared with available laboratory measurements and other theoretical approaches where possible, and overall very good agreement is observed. The model developed in this study addresses directly three shortcomings of existing approaches used for the analysis of FOWTs, namely (i) determination of the elastic responses of the entire structure including the floating platform, (ii) analysis of the motion and elastic response of FOWTs in frequency domain, and (iii) assessment of responses of FOWTs with single or multiple wind towers.

Dynamic reliability analysis of Aerial Building Machine under extreme wind loads using improved QBDC-based active learning

Greenhouses had to be designed to sustain permanent maintenance and crop loads as well as the site-specific climatic conditions, with wind being the most damaging. However, both the structure and foundation are regularly empirically calculated, which could lead to structural inadequacies or cost ineffectiveness. Thus, in this paper, the structural assessment of a multi-tunnel greenhouse was carried out. Firstly, wind loads were assessed through computational fluid dynamics (CFD). Then, the buckling failure mode when either the European Standard (EN) or the CFD wind loads were contemplated was assessed by a finite element method (FEM). Conversely to the EN 13031-1, CFD wind loads generated a suction in the 0–55° region of the first tunnel and a 60% reduction of the external pressure coefficients in the third tunnel was not detected. Moreover, the first-order buckling eigenvalues were reduced (32–57%), which resulted in the need for a different calculation method (i.e., elastoplastic analysis), and global buckling modes similar to local buckling shape were detected. Finally, the foundation was studied by the FEM and a matrix method based on the Wrinkler model. The stresses and deformations arising from the proposed matrix method were conservative compared to those obtained by the FEM.

Tuned Mass Dampers (TMD) have been widely used in the passive vibration control of engineering structures, both under wind and seismic loads. Under wind loads, a proper frequency tuning ensures a significant response reduction of the primary structure. While under wind loads the structure is likely to remain in the elastic range of behaviour, when large earthquakes occur it can experience inelastic deformations and damage, with a consequent de-tuning effect. In this paper, nonconventional TMDs with large mass ratios, realized through Inter-story Isolation Systems (IIS), are considered and the influence of the inelastic behaviour of the primary system on the overall structure response is analysed. In detail, IIS is employed for retrofitting existing masonry buildings through a vertical extension, isolated at its base and built up on the roof of the existing structure. Pivot-type hysteretic models are used to grasp the mechanical behaviour of the masonry structure. Based on a case-study building, time history analyses on 3D Finite Element models are implemented. The results of nonlinear time history analyses show that in the building with the vertical extension both displacements and hysteretic energy dissipated by the masonry piers, are lower than in the as-is building, confirming that, although a de-tuning effect can occur, the inelastic engagement of the original structure is significantly reduced.KeywordsNonconventional TMDMasonry structureMasonry nonlinearitiesSteel vertical additionSeismic retrofit

To address the issues of insulation layer damage and conductor exposure in offshore floating photovoltaic systems occurring in shallow marine regions characterized by significant tidal ranges under multi-field coupling effects, an overhead cable laying scheme based on the hybrid pile–floater structure is proposed, while its mechanical response is investigated in this paper. The motion response model of the floating platform, considering wind load, wave load, current load, and mooring load, as well as the equivalent density and mathematical model of the overhead cable are established. The mechanical response characteristics of the overhead cable are analyzed through finite element analysis software. The results indicate that the overhead cable’s mechanical response is influenced by the span length and coupled wind–ice loads. Specifically, the tension exhibits a nonlinear increasing trend, while the deflection shows differential variations driven by the antagonistic interaction between wind and ice loads. The influence of ice loads on the configuration of overhead cables is significantly weaker than that of wind loads. This study provides crucial theoretical support for enhancing the lifespan of the overhead cable.

Large-span cable-stayed bridges are increasingly becoming a vital component of modern bridge infrastructure due to their efficiency in load distribution, aesthetic appeal, and ability to span significant distances. This study examines the structural and dynamic performance of Azerbaijan’s largest multi-span cable-stayed bridge, which is currently under construction along the MuganlyIsmayilli-Gabala road. With a total length of 1100 meters, the bridge is located in a region of high seismic activity, making stability and structural integrity paramount concerns in its design and construction. A detailed load analysis was conducted, considering both permanent and temporary loads. These include the self-weight of the bridge, vehicle loads, environmental forces such as wind, snow, and ice, as well as the influence of seismic effects. The bridge features multiple cable configurations - 31 6 , 37 6     and 48 6  —each with specific cross-sectional areas and tension forces that ensure structural stability. To mitigate seismic impact, the bridge is equipped with kinematic roller supports between the stiffening beam and its supporting structures, allowing controlled movement during seismic events. The study also focuses on the dynamic behavior of the bridge under various forces, particularly wind loads that induce oscillations in the cables and the stiffening beam. Through finite element analysis, the vertical and horizontal vibration frequencies were calculated, ensuring that resonance conditions are avoided. The results demonstrate that the bridge remains within safe limits for aerodynamic stability, with no risk of excessive oscillations due to wind or traffic loads. Furthermore, the analysis of cable strength and durability confirms that the maximum tension forces are within acceptable limits, with safety margins that comply with international engineering standards. The bridge’s stiffness conditions were verified using deformation calculations, showing that maximum deflections remain within allowable limits, ensuring long-term serviceability. This study provides crucial insights into the design and performance of large-span cable-stayed bridges in seismically active regions. The findings highlight the importance of advanced structural analysis and innovative engineering solutions to enhance stability, durability, and safety. The research contributes to the broader understanding of bridge engineering, offering valuable guidelines for the construction of future large-span cable-stayed structures in challenging environmental conditions.

In the shipbuilding and ship repair industry, the most common surface preparation technique used is abrasive blasting. The abrasive blasting and the other surface preparation techniques are the significant sources of shipyard waste and air pollution. The one of any kind techniques to reduce the hazardous air contaminant associated with the abrasive media is blasting room. The abrasive blasting operation is isolated by the blasting room to reduce the exposure to the shipyard environment. The portable blasting room design has been developed using the modular wall panel system. The research is focused on the strength analysis of portable modular blast room using glass reinforced plastics as the wall panels. The research method has two main steps during the strength analysis of the portable blast room. At first, the geometric form of the modular blast room was developed and defined to obtain the finite element model. Secondly, the load and boundary condition was defined, considering the wind load and the structure weight which are exerted to the blast room structure. The displacement method was adopted for the numerical analysis.