High Wind Loads Research Articles

Research on the Design and Application of Anti-wind devices for Seismically Isolated Buildings

Specialized anti-wind devices were designed and applied to seismically isolated buildings to solve the problem that seismic isolation buildings in areas with high wind loads could not simultaneously meet the requirements of the seismic damping objectives and the wind bearing capacity calculation. Taking an actual project as an example, anti-wind devices are added to the seismic isolation interface, a finite element analysis model of the structure is established and a time-distance analysis calculation is performed, and a synergistic design is carried out for the seismic damping effect and wind-resistant calculation. The results of the study show that the addition of anti-wind devices to reduce the number of lead rubber bearings can simultaneously satisfy the expected seismic damping effect and wind bearing capacity requirements; Numerical analysis of static loading verifies the effectiveness of anti-wind devices; This anti-wind device can be popularized for use in seismically isolated buildings in areas with high wind loads.

Экспериментальные исследования комбинированных анкеров и варианты их практического применения

In the article, the authors for the first time proposed combined anchor structures that can work effectively as wire anchors working on a pulling load, as well as pile anchors working on a pressing force. Such structures can be effectively used as anti-landslide structures, support and anchor foundations, which are also patented by the authors and their designs are given in the article. In practice, such structures are necessary as foundations, for poles of power lines, high towers exposed to high wind loads and other structures. The support can work both on a pressing load and on pulling out, depending on the specific conditions. The research methodology is described and the results of experimental studies are presented. During the research, the following factors were taken as the main factors: the diameter of the pile and the conical tip, the length of the pile part of the combined anchor, the distance from the end of the pile to the conical tip. The pulling force was adopted as an optimization parameter.

Experimental investigation and design consideration on pull-through capacity of a C-shaped purlin section

A small-scale experimental study was carried out to investigate the pull-through failure of the C-shaped Cold-Formed Steel (CFS) roof purlin sections subjected to wind uplift force. The parameters investigated to comprehend the pull-through behavior of roof purlin are thickness, web depth, flange width of the CFS purlin section, and size of the screw head diameter. The test specimens experienced two different modes of pull-through failure (rupture and bearing) along with the prying effect. It was observed that the pull-through failure mode transitions from rupture of the purlin section around the screw fastener in 1 mm thickness to bearing type in 2 mm and 3 mm thicknesses. The test results were compared with existing design limits and previous studies from the literature which concluded that the existing elastic design approach for the service limit state is unconservative. Hence, a suitable design limit to predict the critical pull-through capacity of C-shaped roof purlins under high wind load is proposed. Additionally, reliability studies were carried out to determine the resistance and safety factors for the proposed design equations. The suggested design specifications are applicable and conservative for the material strength in the range of 350 MPa.

Elevational variations in stem hydraulic efficiency and safety of Abies fabri

Abstract The structural and functional traits of coniferous trees can reflect their growth states and adaptive strategies to a harsh environment. However, it is still unclear if and how hydraulic traits of subalpine conifers change with altitude. Therefore, the changes in stem hydraulic characteristics of Abies fabri along an elevational gradient (2700–3700 m a.s.l.) were identified in a subalpine ecosystem in southwest China and linked to anatomical properties. Xylem hydraulic efficiency decreased with increasing elevation. Surprisingly, higher hydraulic dysfunction and vulnerability to embolism occurred at higher altitudes. The trade‐off between hydraulic efficiency and safety was weak in A. fabri at higher elevations. Low temperature and superfluous precipitation may be the main constraints for hydraulic function and mechanical strength ((t/b)2)) in plants at high elevations (p < 0.05). The strongly limited hydraulic transport system reflected the severe growth constraint of A. fabri at high elevations. Although series of anatomical traits varied with elevation (e.g. smaller mean diameter of tracheid, mean hydraulic conduit diameter and mean pit aperture diameter at higher altitude) and revealed the adaptive strategies to enhance embolism resistance, thickness‐to‐span ratio ((t/b)2) played a dominant role in the trade‐off between hydraulic efficiency and safety. Thickness‐to‐span ratio was positively correlated with stem hydraulic conductivity but negatively correlated with percent loss of conductivity and water potential at 50% loss of conductivity, (t/b)2 and specific leaf area. Therefore, plants with better hydraulic and growth states at low elevations could allocate more resources to building up solid mechanical supporting systems to cope with high wind load, while those at high elevations with impaired growth states and limited hydraulic functions had to invest more resources in leaves under the harsh environment. The weak trade‐off between hydraulic efficiency and safety (lower hydraulic efficiency and high risk of embolism) could limit the growth and distribution of A. fabri at timberlines; however, global warming trends may facilitate hydraulic transport and benefit plants' growth in the future. Read the free Plain Language Summary for this article on the Journal blog.

Computational Fluid Dynamics Analysis of the Influence of Openings on Wind Load and Structural Response in Triangular Buildings

Understanding the response of buildings to wind loads is critical, as these forces can generate significant pressure and suction, potentially leading to structural failure if overlooked. This research was focused on examining the effects of openings on triangular-shaped buildings when subjected to high wind load conditions. Utilizing CAD modeling and Computational Fluid Dynamics (CFD) simulations, the analysis was executed through the ANSYS simulation package. Subsequent Fluid-Structure Interaction (FSI) studies were conducted to ascertain shear stress and lateral deformation. The studies encompassed building models both with and without openings, with the evaluation of induced pressure and velocity. The resultant drag on buildings incorporating openings was discovered to be 6679N lower than those without openings. Furthermore, an analysis employing M25 concrete indicated a 33.13$3 \%$ reduction in lateral deformation in buildings with openings as compared to those without. For buildings constructed with M30 concrete, a 32.17$3 \%$ decrease in lateral deformation was observed. Despite the informative findings, it should be recognized that the investigation was confined to a particular range of wind load conditions and did not consider extreme scenarios. Dynamic wind effects and long-term structural behavior were not included in the current analysis. Therefore, while this study elucidates the importance of wind load analysis and structural reinforcement for maintaining building stability, further research is warranted. Such future investigations should consider broader simulation models, encompassing diverse building shapes and wind load conditions, and account for additional influential factors.

Seismic performance cold-Formed steel framed shear walls using in-Frame corrugated steel sheathing

To meet the increasing demand for high strength and non-combustible shear wall systems in mid-rise cold-formed steel (CFS) constructions, this paper investigates the seismic performance and design method of an innovative CFS shear wall system with in-frame corrugated steel sheathing based on previous studies. Shear wall and bearing wall specimens with in-frame corrugated steel sheathing are tested under combined lateral and gravity loading. Simplified numerical models of whole archetype buildings are established. The seismic performance evaluation is performed using methodology recommended in FEMA P695 and the seismic performance factors are examined. The test results show that the shear strength of the innovative shear wall is much higher than currently code certified wood-based shear walls in AISI S400. Also, the shear strength of bearing walls is approximately one-third of the shear strength of shear walls, which proves that bearing walls also contribute significant shear resistance in a structure. The seismic performance evaluation results verified that the existing seismic performance factors (R = Cd = 6.5 and [Formula: see text] = 3.0) for CFS shear walls with flat steel sheathings can also be used for the innovative shear wall system. The innovative CFS shear wall system with in-frame corrugated steel sheathing could be employed for mid-rise buildings in areas that are prone to high seismic and wind loads.

Gaidai-Xing reliability method validation for 10-MW floating wind turbines

In contrast to well-known bivariate statistical approach, which is known to properly forecast extreme response levels for two-dimensional systems, the research validates innovative structural reliability method, which is particularly appropriate for multi-dimensional structural responses. The disadvantage of dealing with large system dimensionality and cross-correlation across multiple dimensions is not a benefit of traditional dependability approaches that deal with time series. Since offshore constructions are built to handle extremely high wind and wave loads, understanding these severe stresses is essential, e.g. wind turbines should be built and operated with the least amount of inconvenience. In the first scenario, the blade root flapwise bending moment is examined, whereas in the second, the tower bottom fore-aft bending moment is examined. The FAST simulation program was utilized to generate the empirical bending moments for this investigation with the load instances activated at under-rated, rated, and above-rated speeds. The novel reliability approach, in contrast to conventional reliability methods, does not call for the study of a multi-dimensional reliability function in the case of numerical simulation. As demonstrated in this work, it is now possible to assess multi-degree-of-freedom nonlinear system failure probability, in the case when only limited system measurements are available.

Optimal configuration of tapered steel gable frames based on total installed costs using the Enhanced Crystal Structure Algorithm

Steel gable frames are the structural system of choice for industrial buildings and warehouses. As the frame span length and column height increase, prismatic members become economically infeasible, whereas tapered members can be optimized to provide the highest material usage efficiency and the least possible cost. The objective of this study is to compare the optimal design of four different practical configurations of tapered steel gable frames against the case of using prismatic members. Therefore, the optimal configuration for each span length, column height, and loading condition can be determined. Five distinct loading conditions are considered including high wind loads, high seismic loads, and low, medium, and high snow loads. The study results led to developing decision support charts to determine the optimal configuration based on the ratio of the material cost to the total installed costs, including material, fabrication, and erection costs. In addition, higher material savings can be achieved by using tapered members with a larger number of member divisions and design variables by about 14% up to 25.3% compared to using only prismatic members.

Improving the design of autonomous lighting complexes

The general world trends in the creation and operation of modern autonomous lighting complexes for various purposes are considered, for which the main features of structural and design solutions are determined. The article analyses the experience of construction and operation of autonomous lighting complexes in Ukraine and calculates the main indicators of their efficiency. According to the results of the analysis, the main problems of operation of the investigated autonomous lighting complexes are identified and requirements for the technical characteristics and design of such complexes are formulated, depending on the purpose and specific climatic conditions of the territory where they are located. Based on the results obtained, the necessity of improving their design with the use of modern equipment and advanced control systems is substantiated. An improved design of autonomous lighting complexes is proposed for their operation under conditions of high wind loads and significant probabilities of ice and frost deposits formation, which involves the use of renewable energy sources and supports with increased mechanical strength. A comparison of different energy sources is made to ensure optimal electricity generation depending on the operating conditions and to meet the requirements for the duration of power supply to the local load. For the purpose of reliable and high-quality operation of the studied lighting complexes, the use of energy storage systems of various types and determination of their optimal capacity are substantiated. The expediency of using the towers made of composite materials to ensure an increased safety margin when operating an autonomous lighting complex in difficult climatic conditions is substantiated. The research of technical and economic parameters of the developed autonomous lighting complex in different operating conditions is carried out. The effectiveness of implementation and operation of the developed autonomous lighting complex in comparison with analogues is proved.

Reliability of toe-nail connections in a gable roof houses under uplift wind loads

The latest devastating hurricanes have caused considerable damage to light frame wooden houses. The detachment of the roofs because of the high uplift wind loads is one of the typical damages. This detachment often occurs at the contact connections in between the roof trusses and the walls of the houses. For several decades, toe-nail connections, which are poor in uplift resistance, have been used in those contacts. The purpose of this paper is to develop an efficient numerical model for performing reliability assessment of wooden roofs under uplift wind loads taking into account the statistical variability in both the load–deflection curve of toe-nails and the uplift wind load. The model utilizes a three-dimensional semi-analytical solution previously developed to predict the behaviour and failure of wood roofs under spatially variable uplift loads. The random characteristics of the toe-nails were calculated based on experimental results found in the literature and were statistically simulated using a beta distribution. The randomness of the wind speed was evaluated using a normal distribution. A full-scale gable roof was considered as a case study to determine the probability of roof failure at different wind speeds, Monte Carlo simulations along with the semi-analytical model were used to obtain the fragility curve based on two different criteria. It was found that beyond a mean wind velocity of 32 m/s, the probability of roof failure increases rapidly.

Ultracompact Dual-Polarized Cross-Dipole Antenna for a 5G Base Station Array With a Low Wind Load

Very high wind loads represent one of the major problems for ultralarge-scale 5G base station arrays in the sub-6 GHz band, where dozens or even hundreds of antennas are used. An ultracompact dual-polarized cross-dipole antenna with an extremely small overall projected area is presented. The projected area is reduced by employing miniaturized cross dipoles and replacing the traditional ground plane with a defected ground structure (DGS) and metal mesh reflector. The DGS is utilized for size reduction and isolation enhancement. Therefore, an array with a low wind load is formed using antennas with an extremely small projected area, and each antenna in the array can be independently packaged using a streamlined radome that is conducive to airflow. The antenna prototype is designed, fabricated, and measured for the sub-1 GHz band. The results show that the impedance bandwidth is 680–970 MHz, the polarization isolation is higher than 20 dB, and the gain is approximately 6.5 dBi. Furthermore, the results verify that the proposed ultracompact antenna with excellent radiation performance is highly suitable for an ultralarge-scale 5G base station array with a low wind load.

Wind Forces on Medium-Span Bridges: A Comparison of Eurocode 1 Part 4 and Computational Fluid Dynamics

Bridges often have complicated geometries in complex terrain where they can be exposed to high wind loading. Current practice in designing for wind can be conservative. The drive for more lean construction motivates the study of computational modelling as an alternative to traditional methods of determining these wind loads. This paper compares wind forces determined using Eurocode 1 Part 4 with those determined by CFD modelling for a given bridge geometry, taking variations in altitude, location, wind speed and wind direction into account. Results indicate that the exposure factors used in Eurocode 1 Part 4 inflate the net wind force values. It was also found that the directional factor is conservative for wind forces on bridge decks but ineffective for wind forces on bridge piers in the x-direction. Furthermore, the Reynolds-Averaged Navier–Stokes equations (CFD) appear to produce smaller values of net wind force than Bernoulli’s equation (Eurocode). Bernoulli’s equation can only be applied to an ideal fluid, and Reynolds-Averaged Navier–Stokes equations can be applied to any viscous fluid—a further concern with the current practice.

Wpływ kształtu wzmacniających profili okiennych na wytrzymałość i sztywność skrętną okien

Leading European manufacturers of profiles intended for the production of construction joinery currently use mainly PVC profiles with various configurations of external and internal shapes, allowing the production of functional products due to their intended use, shape, possibility of building them, maintaining color and maintaining low thermal transmittance coefficients of profiles. It is important to obtain high cross-sectional strengths, especially for torsion and bending. It is related to high wind loads of structures. A profile is made of a PVC with a low Young’s modulus compared to other materials, and thus it has low stiffness and strength indicators. This leads to relatively easy deformation of the joinery profiles during assembly. To avoid this unfavorable effect, the PVC profiles are reinforced with steel sections. Currently, in the industry producing PVC profiles, open steel reinforcement profiles are almost exclusively used. This solution is very disadvantageous for reasons of stiffness. However, manufacturers use such profiles primarily for technological and price reasons. Closed profiles pose many technological problems in their production and are approx. 30% more expensive compared to the corresponding open profiles. This paper presents research on the use of closed steel stiffening sections in place of open profiles. The main advantage of stiffening closed profiles is many times greater bending and torsional stiffness compared to open profiles. The theoretical and experimental studies carried out for selected cross-sections have shown that the stresses in a closed profile are several times lower than in an identical open profile, and the torsional stiffness of a closed profile is even several dozen times higher than that of an identical open profile.

Renewable Electricity Generation in Small Island Developing States: The Effect of Importing Ammonia

Recently, we demonstrated for Curaçao that renewable electricity generation from wind combined with energy storage in the form of ammonia is competitive with imported fossil fuels, such as LNG, oil, and coal. In the current work, we have expanded the model by considering imported green ammonia as an alternative to local electricity generation and storage. Local production of ammonia as an energy storage medium was compared with imported ammonia to make up the electricity produced from onshore wind, for Curaçao and Fiji’s largest island Viti Levu. Curaçao and Viti Levu have been selected as two interesting extremes with favorable and non-favorable wind conditions, respectively. Assuming a market price of 500 USD/t NH3, it is found that importing ammonia is the most feasible solution for both islands, with a levelized cost of electricity (LCOE) of 0.11 USD/kWh for Curaçao and 0.37 USD/kWh for Viti Levu. This compares to 0.12 USD/kWh for Curaçao; however, for Viti Levu, this value increases to 1.10 USD/kWh for a completely islanded system based on onshore wind and imported ammonia. These islands represent two extreme cases in terms of wind load factor and load consistency, as Curaçao has a high and consistent wind load factor when compared to Viti Levu. Thus, the conclusions obtained for these locations are expected to be applicable for other small island developing states.

Opportunities and limitations of thinning to increase resistance and resilience of trees and forests to global change

AbstractWe reviewed recent literature to identify the positive and negative effects of thinning on both stand- and tree-level resistance and resilience to four stressors that are expected to increase in frequency and/or severity due to global change: (1) drought, (2) fire, (3) insects and pathogens, and (4) wind. There is strong evidence that thinning, particularly heavy thinning, reduces the impact of drought and also the risk and severity of fire when harvest slash is burned or removed. Thinning also increases the growth and vigor of residual trees, making them less susceptible to eruptive insects and pathogens, while targeted removal of host species, susceptible individuals and infected trees can slow the spread of outbreaks. However, the evidence that thinning has consistent positive effects is limited to a few insects and pathogens, and negative effects on root rot infection severity were also reported. At this point, our review reveals insufficient evidence from rigorous experiments to draw general conclusions. Although thinning initially increases the risk of windthrow, there is good evidence that thinning young stands reduces the long-term risk by promoting the development of structural roots and favouring the acclimation of trees to high wind loads. While our review suggests that thinning should not be promoted as a tool that will universally increase the resistance and resilience of forests, current evidence suggests that thinning could still be an effective tool to reduce forest vulnerability to several stressors, creating a window of opportunity to implement longer term adaptive management strategies such as assisted migration. We highlight knowledge gaps that should be targeted by future research to assess the potential contribution of thinning to adaptive forest management. One of these gaps is that studies from boreal and tropical regions are drastically underrepresented, with almost no studies conducted in Asia and the southern hemisphere. Empirical evidence from these regions is urgently needed to allow broader-scale conclusions.

Bonded Glass Tubes as Translucent Jacket of the Museum of Fine Arts in Houston – Design, Engineering and Testing

The “Nancy and Rich Kinder Building” is one of three new buildings being constructed as part of the redevelopment of the Museum of Fine Arts in Houston Campus. From the outside, the building is almost completely wrapped in translucent hot‐bent semicircular tubes made of laminated glass (“Cool Jacket”). The glass tubes not only serve as a design element, they also regulate the incidence of daylight and reduce the energy entry into the building. An almost invisible fixing was realized by the use of special structural glazing profiles on the inside of the glass tubes. Both the glass tubes, which are exposed to high thermal stresses, and the adhesive joints, which have to withstand high wind loads, required detailed finite element calculations as well as experimental investigations. The article describes and evaluates the calculations and experiments as well as the design and installation.

Seismic Response of Braced Heavy Timber Frames with Riveted Connections

AbstractBraced timber frames (BTFs) are one the most efficient lateral load–resisting systems to resist earthquake and high wind loads. Design guidelines for this system currently do not exist in C...

Quasi‐static response of a bottom‐fixed wind turbine subject to various incident wind fields

AbstractIn the design of offshore wind farms the simulated dynamic response of the wind turbine structure includes loading from turbulent wind. The International Electrotechnical Commission (IEC) standard for wind turbine design recommends both the Mann spectral tensor model and the Kaimal spectral model combined with an exponential coherence formulation. These models give deviating wind loads. This study compares these two models to a large eddy simulations model and a model based on offshore wind measurements. The comparisons are performed for three situations, covering unstable, neutral and stable atmospheric conditions. The impact of the differences in the wind fields on the quasi‐static response of a large bottom‐fixed wind turbine is investigated. The findings are supported by an assessment of the impact of individual wind characteristics on the turbine responses. The wind model based on measurements causes high tower bottom and blade root flapwise bending moments due to a high wind load at very low frequencies. Low and negative horizontal coherence is obtained using the Mann spectral tensor model. This causes relatively large yaw moments as compared to the results using the other wind models. The largest differences in response are seen in the stable situation. We furthermore show that the quasi‐static wind load has great impact on the total damage equivalent moments of the structure. From the results, we conclude that in the design of large offshore wind turbines one should carefully consider the structure of the turbulent wind. Further, longer simulations than recommended by the standards should be used to reduce uncertainty in estimated response.

Effects of Architectural Irregularities on the Seismic Behavior of Buildings

Cooperation between the architect and the civil engineer has nowadays become essential in any project for the client’s requests’ sake. This study was made to show this idea’s importance and beneficial consequences. For this purpose, a 40-story dual-system high-rise building has been designed to resist moderate seismic and high wind loads. Three main models were formed: Starting with the net model, which is the regular model, followed by the mass irregularity models that were generated for the luxury floor desires (this irregularity was placed in two different locations, namely at the top and middle position), ending with the soft story irregularity models that were cited in the building’s middle and bottom for the gym floor’s need. The positions for each irregularity were tested and compared to those of the regular model under the effect of seismic load on one hand and under the influence of three different wind loads on the other. The required wind loads studied in this article were assigned from the wind speeds of 80, 100 and 120 mph. For these models’ analysis, RSA using finite element method on ETABS was used.The results exhibited that the peak wind speed this building held was 110 mph for both irregularities. Furthermore, the seismically-designed high-rise buildings might not be safe enough to resist a wind load speed of 120 mph. In addition, the middle location is the most preferable locus for these irregularities to occur regarding wind and seismic loads because of its minor displacement, drift and base shear. Besides, it ensured the economic cost of the mass irregularity ($1,706,380), which is in turn less than that of the top position ($1,790,187). The same applies for the stiffness irregularity cost, requiring a budget of $1,632,310 in the middle position but an expense of $1,676,368 for the bottom locus. Although the irregularity’s perfect location seemed unfamiliar, it pursues the sake of the client, the architect and the civil engineer alike.

Parametric study of position of an outrigger-belt system through pushover analysis

This study revolves around the high-rise RCC buildings with lateral force resisting system (LFRS). While constructing a multi-storey building, it is necessary to survey various salient features such as lateral load resistance capacity and lateral stiffness. The LFRS is used to introduce the lateral force resistances in the building and the LFRS used for this study are core and outrigger-belt system. Since the core is applied to the whole building at once, thus application related to it are easier, but when another LFRS (outrigger belt system in this study) which is dedicated to a certain floor, is added in the building, then its position can affect the performance of the building. There has been a lot of theories regarding the optimum positions which show how the position of these storey dependent LFRS can affect the overall performance of the buildings. When a multi-storey building is prone to high intensity earthquake load or heavy wind load, the outrigger-belt and core system would resist the rotation and prevent excessive sway caused by lateral loads. Thus, if proper analysis is performed on the building for optimum position of these systems, then the overall performance can be increased significantly. For this purpose, the buildings of 20-, 25-, and 30-storeys are analysed by Pushover Analysis with two load patterns using Midas GEN. The study is also performed in buildings with different stiffness conditions to understand the overall behaviour of the building for optimum positions. A total of 285 building models are tested using two different load patterns. These buildings differ from each other in terms of position of outrigger, stiffness and number of storeys.