Wind-resistant Design Research Articles

Current Status and Issues of the Wind Resistant Design for the Floating PV Systems

Current Status and Issues of the Wind Resistant Design for the Floating PV Systems

Current Status and Issues of the Wind Resistant Design for the PV Systems Installed on Slopes

Current Status and Issues of the Wind Resistant Design for the PV Systems Installed on Slopes

The Wind Loading Characteristics of MAN Type Dry Gas Storage Tank

The effects of Reynolds number (Re) and surface roughness on the wind pressure coefficient on a MAN type dry gas tank were analyzed in detail by wind tunnel tests. A wind load calculation model was then established, which is suitable for the wind resistant design of the gas tanks. The test results revealed that in the range of 7 × 105 < Re < 1.0 × 106 (supercritical regimes), the drag coefficient (Cd) and wind pressure coefficient remained constant, consistent with 2D cylinders in a uniform flow. However, in common with 2D cylinder flows, the surface roughness with the spacing ratio (λ) greater than 0.9 had a significant effect on the wind pressures coefficient. The minimum pressure coefficient (Cpmin) sharply increased from −2.3 to −0.65 with increasing surface roughness. The corresponding angle for the minimum pressure coefficient θmin was in between 140°and 90°, which was in a gradual decreasing trend with the increase in surface roughness of the model. The calculation method of the wind pressure coefficient with vary surface roughness was proposed, based on which, the calculation results were in good agreement with the test data.

Assessment of TC-Dominated Extreme Wind in the Scenario of Climate Change for Wind-Resistant Design of Super-Tall Buildings

Assessment of TC-Dominated Extreme Wind in the Scenario of Climate Change for Wind-Resistant Design of Super-Tall Buildings

CFD validation of wind pressure distribution on a tall building under the influence of upstream terrain

It is essential to investigate the pressure distribution, aerodynamic coefficients and wind flow fields in-order to predict the wind loads and wind behaviour in building environments. Most of the investigations and international wind load standards haven't highlighted the wind load and wind environment on-and-around buildings under different terrains. The main objective of this investigation is to explore a practical numerical approach for the accurate estimation of wind loads and their impact on buildings under different upstream conditions. In this investigation, simulations are done in IDDES turbulence model along with the formulation of k-ω SST using CFD. Results indicated the influence of ground roughness in pressure distribution on building faces. Furthermore, CFD results over-predicted the experimental values near the edges due to strong shear-flow and expanding wake-vortices. The cross-validation of the mean drag coefficients showed good-agreement. Hence this investigation promotes the practice of IDDES in wind-resistant designs for tall buildings.

Field monitoring and wind tunnel study of wind effects on roof overhang of a low‐rise building

Roof overhang is one of the most easily damaged parts of low-rise buildings during windstorms. To investigate the wind-induced pressure distributions and forces on the roof overhang of a typical low-rise building, field monitoring during two typhoons and detailed wind tunnel test are conducted in this paper. Correlation analysis is performed to analyze the wind pressures on the upper and lower surfaces of the roof overhang. Moreover, cross-comparisons among the wind tunnel testing results, full-scale measurements, and design provisions are made for validation purposes. The comparative study illustrates that the model-scale experimental results of wind pressure coefficients, lift, and bending moment coefficients on the roof overhang are generally in reasonable agreement with the full-scale measurements, except for the peak negative pressure coefficients and lift coefficients for several wind directions. In addition, it is observed that the suctions on the roof overhang determined from the wind tunnel test and the full-scale measurements are lower than those stipulated in ASCE 7-16. The combined field measurement and model testing study aims to further understand the wind effects on roof overhang during windstorms and improve the wind-resistant design of low-rise buildings in tropic cyclone-prone regions.

An Analytical Framework for the Investigation of Tropical Cyclone Wind Characteristics over Different Measurement Conditions

Wind characteristics (e.g., mean wind speed, gust factor, turbulence intensity and integral scale, etc.) are quite scattered in different measurement conditions, especially during typhoon and/or hurricane processes, which results in the structural engineer ambiguously determining the wind parameters in wind-resistant design of buildings and structures in cyclone-prone regions. In tropical cyclones (including typhoons and hurricanes), the inconsistent wind characteristics may be in part ascribed to the complex flow structure with the coexistence of both mechanical and convective turbulence in the boundary layer of tropical cyclones. Another significant contribution to the scattered wind characteristics is due to various measurement conditions (e.g., terrain exposure and height) and data processing schemes (e.g., averaging time). The removal of the inconsistency in the field-measurement system may offer a more rational comparison of measured wind data from various observation platforms, and hence facilitates a better identification scheme of the wind characteristics to guide the urban planning design and wind-resistant design of buildings and structures. In this study, an analytical framework was firstly proposed to eliminate the potential observation-related effects in wind characteristics and then the wind characteristics of seven field measured tropical cyclones (four typhoons and three hurricanes) were comparatively investigated. Specifically, field measurements of wind characteristics were converted to a standard reference station with a roughness length of 0.03 m, observation duration of 10 min for mean wind and averaging time of 3 s for gusty wind at a 10 m height. The differences of the measured wind characteristics between the typhoons and hurricanes were highlighted. The standardized turbulent wind characteristics under the analytical framework for typhoons and hurricanes were compared with the corresponding recommendations in standard of American Society of Civil Engineers (ASCE 7-10) and Architectural Institute of Japan Recommendations for Loads on Buildings (AIJ-RLB-2004).

Exploratory study on wind-adaptable design for super-tall buildings

Wind-adaptable design (WAD) provides a new method for super-tall buildings to lessen design conflicts between architectural prerequisites and aerodynamic requirements, and to increase the efficiency of structural system. Compared to conventional wind-resistant design approach, the proposed new method is to design a building in two consecutive stages: a stage in normal winds and a stage during extreme winds. In majority of time, the required structural capacity is primarily for normal wind effects. During extreme wind storms, the building\'s capacity to wind loads is reinforced by on-demand operable flow control measures/devices to effectively reduce the loads. A general procedure for using WAD is provided, followed by an exploratory case study to demonstrate the application of WAD.

Estimation Algorithm for Topographic Factor of Wind Load Based on Spatial Information

This study proposes an algorithm to calculate the wind speed factor to determine the impact of wind on topography. To reflect the relevant topographic factors, such as peak and index point location information, distance, and range, a three-part estimation algorithm was developed to search for a peak, calibrate the determined peak, and calculate the topographic factor within the research area. Terrain analysis was performed after applying the algorithm to terrains with varying characteristics. The new algorithm applies spatial information along with the architectural information and makes it possible to estimate the topographic factors more quantitatively and objectively than current methods can, and it is also able to include geographic features. This method is expected to eliminate inaccuracies that occur when building designers calculate topographic factors subjectively, and contributes to the wind resistance design of buildings in a more logical manner. Keywords: Wind Load, Wind Velocity, Topographic Factors, GIS

Numerical evaluation of vortex-induced vibration amplitude of a box girder bridge using forced oscillation method

The evaluation of the amplitude of the vortex-induced vibration (VIV) of a long-span bridge is necessary to implement a wind-resistant design. The development of high-performance computing has led to the use of computational fluid dynamics (CFD) in this domain, but the evaluation of VIV amplitude using the free vibration method in CFD incurs a high computational cost because of the small negative aerodynamic damping in the wind speed region of VIV. In this study, the use of flutter derivatives based on the forced oscillation method with a large eddy simulation is proposed for evaluating the VIV amplitude to reduce computational cost. The heaving VIV amplitude of a box girder was evaluated using simulated flutter derivatives and the results were validated by corresponding free vibration wind tunnel tests. Because the aerodynamic damping obtained by the flutter derivatives showed a clear dependence on the oscillation amplitude, the VIV amplitude can be evaluated using the proposed method. The effects of the spanwise domain size and Reynolds number were also significant.

Stochastic harmonic function based wind field simulation and wind-induced reliability of super high-rise buildings

Wind field simulation and wind-induced reliability assessment are two critical steps in wind-induced vibration analysis and design of super high-rise buildings. Owing to its simple algorithm and rigorous theoretical basis, the spectral representation method (SRM) is widely used in practice. However, the SRM still encounters the computational challenge due to the Cholesky decomposition with respect to the crossing-power spectral density (PSD) matrix, particularly in the simulation of multi-variate random processes of large-size wind fluctuation fields. To circumvent this challenge, the stochastic harmonic function based spectral representation method (SHF-SRM) proposed in recent years is extended to the simulation of multi-variate random processes. In conjunction with the probability density evolution method (PDEM), the stochastic response analysis and reliability assessment of wind-induced random vibration of structures is addressed. For illustrative purposes, the wind field simulation and wind-induced vibration and reliability assessment of a 417.7 m high building are carried out. The numerical example proves the effectiveness of the SHF-SRM in simulating multi-variate random processes, and reveals the value of reliability assessment in terms of the global reliability and the time-variant reliability for the enhancement of wind-resistant design of high-rise buildings.

Performance-Based Wind-Resistant Optimization Design for Tall Building Structures

This paper presents a novel framework for the performance-based wind-resistant design of tall buildings accounting for the joint probability distribution of wind speed and direction obtained from long-term wind measurements of local meteorological stations. The joint probability distribution of the wind speed and direction, as well as the uncertainties and probability distributions of natural frequencies and damping ratios, are integrated to investigate the realistic structural performance of optimized target buildings under the wind action. A procedure on the performance-based wind-resistant optimization design of tall buildings is then proposed by adopting the optimality criteria algorithm. The proposed framework is applied to the Commonwealth Advisory Aeronautical Research Council building; the total weight and sizes of structural members are selected as the objective function and design variables in the optimization process, respectively. Compared with the deterministic constraints adopted in the conventional optimization procedure, the optimization constraint conditions in this paper are expressed by the failure probabilities in terms of the maximum displacement, interstory drift, and wind-induced acceleration responses at different design levels, which are associated with different return periods required by the strength and serviceability criteria in the performance-based wind engineering design. The mapping transformation method and checking point algorithm in structural reliability theory are adopted to conduct reliability analysis on the probability constraints in the optimization procedure. The optimized results are analyzed and discussed in the numerical example to verify the effectiveness of the proposed performance-based wind-resistant optimization design of tall buildings.

Numerical Investigation of Wind Pressure Coefficients for Photovoltaic Arrays Mounted on Building Roofs

The wind pressure distribution on the photovoltaic (PV) array is of great importance to the wind resistance design. The flow field related to the pressure can be influenced significantly by the turbulence induced by the building roof edge (Kopp et al., 2012) and it is essential to consider the building effect during the investigation. However, most CFD (computational fluid dynamics) investigations of wind pressure distribution on the PV array are limited to ground mounted PV array without the building. There is a necessity to extend the application of CFD method to flows around roof-mounted PV array. This study investigated the wind pressure distributions on PV arrays mounted on building roofs by means of Reynolds-averaged Navier-Stokes (RANS) approach using the FLUENT software. Since RANS models are sensitive to the fiow condition, several RANS models are adopted and the most accurate RANS model for predicting this type of flow is identified based on a comparison with the wind tunnel experimental results. The SST Κ-ω model can predict the highest net mean wind uplift located at panels upstream accurately and is further applied for the parameter analysis to facilitate the installation of roof-mounted PV array. Numerical simulations of the wind flow field for wind angles between 0° to 180° were carried out at intervals of 20°, and the resulted net pressure distributions were presented. The influences of tilt angles of the PV array were investigated and the pressure distributions of PV panels were related to the flow field. Moreover, the effects of clearance between the PV array and building roof on the flow fields and pressure distributions of the PV array related to PV array tilt angle are studied.

Experimental investigation of wind-induced internal pressures in nominally sealed building structures

The action of internal pressure cannot be neglected in wind-resistant design of large-span structures, high-rise buildings, and low-rise residential buildings. In this study, the internal pressure characteristics were first measured in still air in a completely closed building structure without any leakage. Then a series of wind tunnel tests were conducted to study the probability density distribution characteristics of the internal pressure responses in a nominally sealed building with background leakage. The mean and peak internal pressure responses associated with different background leakage distributions and wind directions were further investigated, and the experimental results were compared with those suggested by the Chinese wind load code GB50009-2012. The results indicated that the internal pressure in the completely closed building was non-stationary, and varied significantly when collected at different time points. Furthermore, a period of about 24 h was observed from the measured time history of internal pressure over 9 d. The internal pressure in a nominally sealed building structure nearly fitted a normal Gaussian distribution. When background leakage was uniformly arranged on the surface of the building, the mean internal pressure coefficient remained unchanged with increasing background leakage, varying within the range from −0.15 to −0.14, indicating lower magnitudes than the value of −0.2 suggested by the Chinese wind load code. The minimum negative peak internal pressure coefficient was −0.255 when the peak factor was 3.5, indicating a lower magnitude than the value of −0.326 calculated in the Chinese wind load code.

Extreme Events design and Mitigation Methods: A Review

Recently, extreme events have highlighted their potentially tragic effects on structural and infrastructure systems. Resilience of the Community to these extreme vents is an important issue of increasing more concern for developing design methods. Such extreme events scenarios involve many uncertainties, such as the intensity, location, and period. The extreme events may include those caused by various natural or manmade hazards, such as earthquake, strong winds, fire, blast, etc. Compared to other events, earthquake and wind are particularly critical due to their significant threats to the global structure performance and more challenges for design. Researchers have recognized that proper evaluation, modeling, and assessment of the effects of extreme events are fundamental to ensure the desired performance of structures. Therefore, the concern for developing appropriate methodologies to evaluate and design structures that can withstand the effects of extreme events has become a very active field of research in recent years. Improvement of building codes and development of new strategies are needed to mitigate the disastrous effects of extreme events. This paper presents a comprehensive review of literature surrounding designing building structures for extreme events. First, a general overview of the extreme events design and different objectives of approaches is conducted. Furthermore, a review related literature surrounding designing for earthquake resistance guidelines is presented, also highlights Performance-Based Seismic Design objectives. The available literature includes many studies for the provisions included in different design codes (China, United States and Europe). A review of literature related to wind resistance design with an overview of Performance Based Wind Design of building design method for the control of winds impacting on building structures is also presented.

ALE-VMS methods for wind-resistant design of long-span bridges

For unsteady aerodynamics, the Arbitrary Lagrangian-Eulerian Variational Multi-Scale (ALE-VMS) formulation for incompressible flows has proven an accurate and powerful method. In this paper we present an overview of some of its applications to wind engineering of long-span bridges, including flutter and buffeting analysis and vortex-induced vibrations. In general the numerical results compare well with the companion wind-tunnel experiments. Further, we use the method to address more special topics of bluff-body aerodynamic; the impact of inlet turbulence on the self-excited forces and the nonconforming span-wise coherence structures of turbulence and buffeting forces. The present work demonstrates the completeness and accuracy of ALE-VMS, and proves it to be a viable engineering tool for bridge aerodynamics.

Field Research on the Wind-Induced Response of a Super High-Rise Building under Typhoon

This paper simultaneously measures the characteristics of wind on the roof and the acceleration responses of the 10th, 18th, 25th, 32nd and 41st floors of a high-rise building in Wenzhou during the passing of typhoons between 2014 and 2016. This paper also analyses the dynamic characteristics and wind-induced response of buildings by using Welch and improved Natural Excitation Technique–Eigensystem Realisation Algorithm methods. The results show that the typhoons that affected Wenzhou are dominated by wind from the east, northeast and northwest. The acceleration response probability densities of different floors during Typhoons Chan-hom and Dujuan are similar to the Gaussian distribution. The first-order natural frequencies of the two wind directions of the test building are 0.390 and 0.409, which are in good agreement with Tamura’s prediction results. The relevant amplitude and frequency characteristics of the first three modes are investigated in detail according to the nonlinear characteristics of the measured building. The first-, second- and third-order damping ratios of the structure during Typhoons Chan-hom and Dujuan increased with the peak acceleration, whereas the damping during Typhoon Fung-wong remained almost unchanged. The root mean square of the acceleration response of the building structure during Typhoons Chan-hom and Dujuan increased with the wind speed. However, the increase rate of Typhoon Chan-hom was small, possibly because the angle between the incoming flow and the building is 45°, and the acceleration response in the downwind and crosswind directions is not apparent. The measured results show that the working environment of the staff at the top of the building under the influence of the typhoon also meets comfort requirements. The measured data and statistical parameters provide a valuable reference for the wind-resistant design of high-rise buildings in typhoon-prone areas.

Wind-resistant design and safety evaluation of cooling towers by reinforcement area criterion

Wind loads are the predominant loads of all the various loading combinations in structural design of cooling towers. Existing wind loading codes have a basic single interference factor and a simplified two-dimensional static wind pressure distribution formula, and do not enable accurate structural safety/reliability evaluation under dynamic wind loads. Among the various Equivalent Static Wind Loadings (ESWLs), the reinforcement-area-based ESWL is selected in this study, and the extreme reinforcement area considering wind directionality effect and nonuniform circumferential wind pressure is expressed as the equivalent criterion of reinforcement area envelope.A structural safety evaluation method, based on this innovative cooling tower design criterion, is derived as the dynamic reinforcement area envelope concept. The effects of time-variant weighted internal forces and non-Gaussian peak factor for the reinforcement area envelope are considered. The reinforcement area envelopes are compared with those from three different codes based on traditional simplified ESWLs. Finally, the results show that the existing loading codes do not cover the effects of interference amplification for structural safety. An alternative framework based on the reinforcement area criterion of weighted dynamic interval forces and its extreme value envelope are proposed, which can optimize both the economy and the structural safety design of cooling towers.

Wind-induced tower crane vibration and safety evaluation

The maximum wind load direction of tower crane is considered to be perpendicular to its jib. The interference effects of its different segments and across-wind loads are ignored in traditional crane safety evaluation. This study proposes a general scheme for the safety evaluation of tower cranes under fluctuating wind loads. The wind coefficients of a full-scale model of a tower crane were calculated by computational fluid dynamics, and then the time history of wind loads, simulated through the autoregressive method, were applied to the finite element model of a tower crane. The results reveal that the maximum along-wind load direction deflected 30°–60°, and the mean ratio of the absolute value of the across-wind coefficient to the along-wind coefficient of the tower crane was 8.56%, which indicated that the across-wind loads should be taken into account in wind-resistant design. Comparing the wind-induced responses of four typical wind directions, the maximum displacement, the bending stress and the axial stress of the tower crane occurred in the positive direction. Furthermore, the maximum acceleration of the cat-head was 0.028 m/s2, which met the comfort requirements of the operator. Although the tower crane met the strength and static stiffness requirements of design rules, the maximum bending stress at the junctions between the jib and the slewing platform, the counterweight and the counter-jib, exceeded the allowable stress, and the first modal of the tower crane was excited. These results warrant considering the effect of fluctuating wind loads in the safety evaluation of a tower crane.

Modeling and simulation of bridge-section buffeting response in turbulent flow

Buffeting analysis plays an important role in the wind-resistant design of long-span bridges. While computational methods have been widely used in the study of self-excited forces on bridge sections, there is very little work on applying advanced simulation to buffeting analysis. In an effort to address this shortcoming, we developed a framework for the buffeting simulation of bridge sections subjected to turbulent flows. We carry out simulations of a rectangular bridge section with aspect ratio 10 and compute its aerodynamic admittance functions. The simulations show good agreement with airfoil theory and experimental observations. It was found that inflow turbulence plays an important role in obtaining accurate wind loads on the bridge sections. The proposed methodology is envisioned to have practical impact in wind engineering of structures in the future.