Wind Loading Codes Research Articles

Experimental study of wind loads on gable roofs of low-rise buildings with overhangs

Gable roofs with overhangs (eaves) are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gable roofs of low-rise buildings are investigated by a series of wind tunnel tests which consist of 99 test cases with various roof pitches, height-depth ratios and width-depth ratios. The block pressure coefficients and worst negative (block) pressure coefficients on different roof regions of low-rise buildings are proposed for the main structure and building envelope, respectively. The effects of roof pitch, height-depth ratio, and width-depth ratio on the pressure coefficients of each region are analyzed in detail. In addition, the pressure coefficients on the roofs for the main structure and building envelope are fitted according to roof pitch, height-depth ratio and width-depth ratio of the low-rise building. Meanwhile, the rationality of the fitting formulas is verified by comparing the fitting results with the codes of different countries. Lastly, the block pressure coefficients and worst negative pressure coefficients are recommended to guide the design of low-rise buildings in typhoon area and act as references for the future’s modification of wind load codes.

Numerical and experimental study of steel wire mesh and basalt fibre mesh strengthened structural insulated panel against projectile impact

Extreme wind events caused damages and losses around the world every year. Windborne debris impact might create opening on building envelop, which would lead to the increase in internal pressure and result in roof being lift up and wall collapse. Some standards including Australia Wind Loading Code (AS/NZS 1170:2:2011, 2011) put forward design criteria to protect structures against windborne debris impacts. Structural insulated panel with Oriented Strand Board skin and expanded polystyrene core has been increasingly used in the building industry. Its capacity was found insufficient to resist the windborne debris impact in cyclonic areas defined in the Australian Wind Loading Code. Therefore, such panels need be strengthened for their applications in construction in cyclonic areas. In this study, impact resistance capacities of seven structural insulated panels strengthened with steel wire mesh and basalt fibre mesh were experimentally and numerically investigated. The impact resistance capacities were identified by comparing the damage mode, residual velocity and unpenetrated length of projectile after impact. Experimental results clearly demonstrated the enhancement of the impact resistance capacities of panels strengthened with steel wire mesh and basalt fibre mesh. Finite element model was developed in LS-DYNA to simulate the dynamic response of the structural insulated panels under windborne debris impact. The accuracy of the numerical model was validated with the testing data.

Consistent inflow boundary conditions for modelling the neutral equilibrium atmospheric boundary layer for the SST k-ω model

Modelling an equilibrium atmospheric boundary layer (ABL) in computational wind engineering (CWE) and relevant areas requires the boundary conditions, the turbulence model and associated constants to be consistent with each other. Among them, the inflow boundary conditions play an important role and determine whether the equations of the turbulence model are satisfied in the whole domain. In this paper, the idea of modeling an equilibrium ABL through specifying proper inflow boundary conditions is extended to the SST k-w model, which is regarded as a better RANS model for simulating the blunt body flow than the standard k-w model. Two new sets of inflow boundary conditions corresponding to different descriptions of the inflow velocity profiles, the logarithmic law and the power law respectively, are then theoretically proposed and numerically verified. A method of determining the undetermined constants and a set of parameter system are then given, which are suitable for the standard wind terrains defined in the wind load code. Finally, the full inflow boundary condition equations considering the scale effect are presented for the purpose of general use.

Experimental and numerical study of basalt fibre cloth strengthened structural insulated panel under windborne debris impact

Strong wind causes damages and losses around the world. The windborne debris carried by strong wind might impact on building and create openings on the building envelop, which might threaten the occupants and cause further damages to the building. To address this issue, some wind loading codes including the Australian Wind Loading Code (AS/NZS 1170:2:2011) give design requirements. The resistance capacity of oriented strand board skins structural insulated panel was investigated and proved having low resistance to the projectile impact, and could not meet the impact resistance requirement for application in cyclonic region C and D defined in Australian Wind Loading Code. In this study, basalt fibre cloth is used to strengthen oriented strand board structural insulated panel to increase its capacity to resist windborne debris impact. This paper presents experimental and numerical study of structural insulated panel with or without basalt fibre cloth strengthening under windborne debris impact. Five specimens with different configurations were tested. The dynamic responses were quantitatively compared in terms of residual speed of debris after impact. The results indicate that basalt fibre cloth enhanced the resistance capacity of oriented strand board structural insulated panel. A numerical model is developed in LS-DYNA to simulate the debris impact. The testing results are used to verify the accuracy of the numerical model, which can be used in subsequent parametric studies.

Comparison of Static Wind Load on High Rise Building According to Different Wind Loading Codes and Standards

Comparison of Static Wind Load on High Rise Building According to Different Wind Loading Codes and Standards

Laboratory test and numerical study of structural insulated panel strengthened with glass fibre laminate against windborne debris impact

Cyclone and tornado as common nature disasters have caused devastating damages and losses around the world. In such events loose objects might be lifted and propelled by strong wind as the windborne debris, which is a potential hazard to the building facade because windborne debris impact may create openings on the building envelop, threaten the safety of occupants inside the building and cause further damages to the structure. Some wind loading codes e.g., the Australian Wind Loading Code (AS/NZS 1170:2:2011) specifies the design requirements to address this issue. On the other hand, structural insulated panel (SIP) has been increasingly used in building constructions owing to the advantages of thermal insulation and easy to build, but it is vulnerable to windborne debris impact owing to its insufficient impact resistance capacity. This disadvantage prevents the wide applications of SIP in regions with strong winds, such as the Cyclone region C and D defined in Australian Wind Loading Code. In this study, glass fibre laminate was used to strengthen SIP with OSB (Oriented Strand Board) skins to improve its capacity to resist windborne debris impact. One unstrengthened and six strengthened SIP panels were manufactured and tested by using a pneumatic cannon system. Two high speed cameras were used to capture failure modes and dynamic responses. The effectiveness of glass fibre laminate strengthening was examined and compared in terms of the residual velocity of the projectile. A numerical model was also developed to simulate the laboratory tests. The accuracy of the model was calibrated by the test results. The validated numerical model was then used to conduct more numerical simulations to obtain vulnerability curves of OSB skin SIP panels against windborne debris impact.

Experimental investigations of fabric material against projectile impacts

Air supported structures made of PVC coated polyester fabric materials have been used in industrial and commercial building constructions. If they are used in cyclonic regions, the structure envelop might be impacted by windborne debris. The windborne debris might perforate the fabric material, which not only results in total collapse of the structure, flying debris at high speed also imposes threats to people and facilities inside the structure. In this study, the penetration resistant capability of PVC coated polyester fabric material commonly used in air supported structures construction was tested by using a pneumatic cannon system. The impact loading from windborne debris equivalent to a timber projectile of 4kg mass as specified in the Australian Wind Loading Code (AS/NZS 1170.2:2011) was applied in the test. The failure and damage modes under various projectile impact scenarios were observed and compared. Its capability of resisting projectile impact was assessed. The performances of PVC coated polyester fabric material were examined quantitatively in terms of projectile residual velocity and energy absorption. The effects of various projectile velocity, impact location, fabric pretension and boundary condition on their penetration resistance performance were studied. The testing results will benefit construction designers involved in the fabric material applications in high wind speed area.

Comparative Analysis of Sino-Foreign Wind Load Standard

It has great significanceto conduct comparative analysis on wind load criteria at home and abroad forimproving anti-wind load capacity of the structure. A brief overview of Chinese,American, European and Australia wind load design codes of structure ispresented in this paper. The difference among these wind load codes, theadvantages and disadvantages of Chinese related standards are pointed out.Through comparison of wind load standard between Chinese code and otherstandards, through learning from foreign experience about the determination ofwind load criteria, improvement of wind load of electrical equipment andstandard revised recommendations are provided.

Wind-excited stochastic vibration of long-span bridge considering wind field parameters during typhoon landfall

With the assistance of typhoon field data at aerial elevation level observed by meteorological satellites and wind velocity and direction records nearby the ground gathered in Guangzhou Weather Station between 1985 and 2001, some key wind field parameters under typhoon climate in Guangzhou region were calibrated based on Monte-Carlo stochastic algorithm and Meng\'s typhoon numerical model. By using Peak Over Threshold method (POT) and Generalized Pareto Distribution (GPD), Wind field characteristics during typhoons for various return periods in several typical engineering fields were predicted, showing that some distribution rules in relation to gradient height of atmosphere boundary layer, power-law component of wind profile, gust factor and extreme wind velocity at 1-3s time interval are obviously different from corresponding items in Chinese wind load Codes. In order to evaluate the influence of typhoon field parameters on long-span flexible bridges, 1:100 reduced-scale wind field of type B terrain was re-illustrated under typhoon and normal conditions utilizing passive turbulence generators in TJ-3 wind tunnel, and wind-induced performance tests of aero-elastic model of long-span Guangzhou Xinguang arch bridge were carried out as well. Furthermore, aerodynamic admittance function about lattice cross section in mid-span arch lib under the condition of higher turbulence intensity of typhoon field was identified via using high-frequency force-measured balance. Based on identified aerodynamic admittance expressions, Wind-induced stochastic vibration of Xinguang arch bridge under typhoon and normal climates was calculated and compared, considering structural geometrical non-linearity, stochastic wind attack angle effects, etc. Thus, the aerodynamic response characteristics under typhoon and normal conditions can be illustrated and checked, which are of satisfactory response results for different oncoming wind velocities with resemblance to those wind tunnel testing data under the two types of climate modes.

Gust durations, gust factors and gust response factors in wind codes and standards

This paper discusses the appropriate duration for basic gust wind speeds in wind loading codes and standards, and in wind engineering generally. Although various proposed definitions are discussed, the 'moving average' gust duration has been widely accepted internationally. The commonly-specified gust duration of 3-seconds, however, is shown to have a significant effect on the high-frequency end of the spectrum of turbulence, and may not be ideally suited for wind engineering purposes. The effective gust durations measured by commonly-used anemometer types are discussed; these are typically considerably shorter than the 'standard' duration of 3 seconds. Using stationary random process theory, the paper gives expected peak factors, g w, as a function of the non-dimensional parameter (T/τ), where T is the sample, or reference, time, and τ is the gust duration, and a non-dimensional mean wind speed, U. T/L w, where U is a mean wind speed, and L w is the integral length scale of turbulence. The commonly-used Durst relationship, relating gusts of various durations, is shown to correspond to a particular value of turbulence intensity I u, of 16.5%, and is therefore applicable to particular terrain and height situations, and hence should not be applied universally. The effective frontal areas associated with peak gusts of various durations are discussed; this indicates that a gust of 3 seconds has an equivalent frontal area equal to that of a tall building. Finally a generalized gust response factor format, accounting for fluctuating and resonant along-wind loading of structures, applicable to any code is presented.

Aerodynamic and peak response interference factors for an upstream square building of identical height

The wind loading of tall buildings in an urban environment is often greatly affected by aerodynamic interference resulting from the interaction of approaching wind with upstream and adjacent structures. Interference effects are not currently considered in wind loading codes, primarily due to the complexity of involved variables. Advice on building configurations which have the potential to generate problematic interference effects would be useful for structural engineers and urban planners. Wind tunnel tests were carried out to assess the interference effects associated with a single upstream building having identical height and geometry to the building of interest. The data are presented as interference factors (IFs) relating the loading and response under interference to that of an isolated building, and the underlying aerodynamic mechanisms are discussed. Contour plots are presented and discussed for IFs corresponding to: (i) the aerodynamic wind loading and; (ii) the peak response. The interference factors associated with the peak responses are useful for the identification of potential interference issues in the preliminary design or siting phase of a project. The results indicate that, depending on combinations of exposure and dynamic properties, the peak response IF may approach the same order as the partial wind load factor in some codes.

Effects of vortex shedding in arrays of long inclined flat plates and ramifications for ground-mounted photovoltaic arrays

Many wind loading codes and standards define flexible structures as slender structures that have a fundamental natural frequency less than 1Hz. This paper demonstrates that this is not a suitable threshold for small structures like ground-mounted arrays of photovoltaic panels because structures this small can experience both self-excitation and buffeting from upwind panels at frequencies well above this value during both serviceability and design wind events.

A Study of Corrolink Structural Insulated Panel (SIP) to Windborne Debris Impacts

Structural insulated panel (SIP) is considered as a green panel in construction industry because of the low thermal conductivity of the sandwiched EPS core (i.e extended polystyrene). It is a lightweight composite structure and is widely used in commercial, industrial and residential buildings to construct the building envelop including roof and wall. The windborne debris driven by cyclone or hurricane usually imposes intensive localized impact on the structural panel, which might create opening to the structure. The opening on the building envelope might cause internal pressures increase and result in substantial damage to the building structures, such as roof lifting up and wall collapse. The Australian Wind Loading Code (version 2011) [1] requires structural panels to resist projectile debris impact at a velocity equal to 40% of the wind speed, which could be more than 40 m/s in the tropical area with the wind speed more than 100m/s. In this study, two kinds of SIP under projectile debris impact were investigated, i.e. “Corrolink” and “Double-corrolink” composite panels shown in Fig. 1. Laboratory tests were carried out by using pneumatic cannon testing system to investigate the dynamic response of composite panels subjected to wooden projectile impacts. The failure modes were observed. The structural dynamic responses were also examined quantitatively based on the deformation and strain time histories measured in the tests. The penetration resistance capacity of panels subjected to windborne debris impact was assessed.Fig. 1 Schematic diagrams (L) Corrolink panel; (R) Double-corrolink panel [2]

Numerical Study of Corrugated Metal Panels Subjected to Windborne Debris Impacts

Hurricane, typhoon and cyclone take place more and more often around the world with changing climate. Such nature disasters cause tremendous economic loss and casualty. Various kinds of windborne debris such as compact-like, plate-like and rod-like objects driven by hurricane usually imposes localized impact loading on the structure envelopes such as cladding, wall or roof, etc. The dominant opening in the envelope might cause serious damage to the structures, even collapse. To withstand the impact of such extreme event, the requirements on panel capacity to resist windborne debris impact has been presented in the Australian Wind Loading Code (2011) [1]. Corrugated metal panels are widely used as building envelop. In a previous study, laboratory tests have been carried out to investigate the performance of corrugated metal panels subjected to a 4kg wooden projectile by considering various impact locations, impact velocities and boundary conditions. In this study, numerical models were developed to simulate the responses of the corrugated metal panels subjected to wooden debris impacts by using commercial software LS-DYNA. The predicted data from the numerical simulations were compared with the experimental results. The validated numerical model can be used to conduct intensive numerical simulation to study the failure probabilities of corrugated structural panels subjected to windborne debris impacts.

Failure analysis of corrugated panel subjected to windborne debris impacts

With the changing climate, more and more natural disasters such as cyclone, hurricane and typhoon take place around the world, which cause tremendous loss and damage. Damages of building structures by windborne debris impacts have been reported in almost all the previous major wind events. The windborne debris usually imposes localized impact loading and creates an opening on the building envelope, which might trigger serious damages to the building structures such as roof lift-up and collapse because strong wind pressures propagating into the structure. To withstand the impact of such extreme event, climate adaptation engineering solutions and technique need to be provided or improved for the building protection. The capacity requirement of panels to resist windborne debris impact is given in the Australian Wind Loading Code (AS/NZS 1170.2:2011) [1]. Corrugated metal panel, widely used as building envelope such as roof and wall cladding, might subject to the windborne debris impact. This study evaluates the capacity of corrugated panels to resist wind borne debris impact. Laboratory tests were carried out on corrugated metal panels of dimension 0.76m by 1.2m subjected to 4kg wooden projectile impacts. The effect of various impact locations, impact velocities and boundary conditions on their performance has been studied. The failure and deformation modes under various impact scenarios were observed and compared. The dynamic responses were examined based on the deformations and the strains on the panel back face. The perforation resistance capacity of panels subjected to windborne debris impact were assessed and analyzed. In addition, a numerical model was developed in LS-DYNA to simulate the response and failure of the corrugated panel under windborne debris impact. The accuracy of the numerical model was calibrated with the test data. The validated numerical model was then used to obtain the results such as impact force, boundary reaction force and energy absorption. The vulnerability curve of the corrugated panel against windborne debris impact was also derived.

Experimental and numerical study of composite lightweight structural insulated panel with expanded polystyrene core against windborne debris impacts

Natural disasters such as cyclone, hurricane, tornado and typhoon cause tremendous loss around the world. The windborne debris usually imposes high speed localized impact on the building envelope, which may harm people inside the building and create dominant openings. A dominant opening in the building envelope might cause internal pressure increasing and result in substantial damage to the building structures, such as roof lifting up or even collapse. To withstand the impact of such extreme event, the penetration resistant capacity of wall or roof panels to windborne debris impact should meet the requirements specified in the wind loading codes, e.g., the Australian Wind Loading Code (AS/NZS 1170.2:2011). In this study, a composite Structural Insulated Panel (SIP) with Extended Polystyrene (EPS) core sandwiched by flat metal skins that is commonly used in building industry was investigated. To study the structural response and penetration resistant capacity of the composite panel against windborne debris impacts, a series of laboratory tests were carried out by using a pneumatic cannon testing system. The effects of various specimen configurations, impact locations and debris impact velocities on their performance were investigated. The failure modes under various projectile impact scenarios were observed and compared by using two high-speed cameras. The dynamic responses were examined quantitatively in terms of the opening size, residual velocity of projectile, deformation and strain time histories on the back skin measured in the tests. The penetration resistance capacity of the panels subjected to windborne debris impact were examined and analyzed. In addition, numerical models were developed in LS-DYNA to simulate the response and damage of the composite SIP under windborne debris impact. Laboratory tested panels were first modeled. The test data was used to calibrate the accuracy of the numerical model. The validated numerical model was then used to conduct more numerical simulations to obtain more results such as energy absorption, impact force and vulnerability curve of the SIP against windborne debris impact.

Comparison and harmonization of building wind loading codes among the Asia-Pacific Economies

This paper reviews wind loading codes and standards in the Asia-Pacific Region, in particular in the 15 countries and areas. A general description of wind loading model is given as a famous wind loading chain described by four variables including velocity pressure, exposure factor, pressure coefficient, and gust response factor. Through the APEC-WW Workshops and the extensive calculations for three examples of low, medium and high rise buildings, these four important variables of wind loads are evaluated and compared with statistical parameters, mean values and coefficients of variation. The main results of the comparison show some differences among the 15 economies, and the reasons and further incorporation are discussed and suggested.

Numerical simulation of wind loading on roadside noise mitigation structures

Numerical research on four typical configurations of noise mitigation structures and their characteristics of wind loads are reported in this paper. The turbulence model as well the model parameters, the modeling of the equilibrium atmospheric boundary layer, the mesh discretization etc., were carefully considered in the numerical model to improve the numerical accuracy. Also a numerical validation of one configuration with the wind tunnel test data was made. Through detailed analyses of the wind load characteristics with the inclined part and the wind incidence angle, it was found that the addition of an inclined part to a noise mitigation structure at-grade would affect the mean nett pressure coefficients on the vertical part, and that the extent of this effect depends on the length of the inclined part itself. The magnitudes of the mean nett pressure coefficients for both the vertical part and the inclined part of noise mitigation structure at-grade tended to increase with length of inclined part. Finally, a comparison with the wind load code British/European Standard BS EN 1991-1-4:2005 was made and the envelope of the mean nett pressure coefficients of the noise mitigation structures was given for design purposes. The current research should be helpful to improve current wind codes by providing more reasonable wind pressure coefficients for different configurations of noise mitigation structures.

Introduction and Comparison of Wind Load Codes for Advanced Structure between Chinese, American and British

China is developing overseas construction projects, it is necessary for the designers to grasp codes. This paper compares and analyzes Chinese code GB50009-2001, American standard ASCE/SEI7-05 and British standard BS6399-2 about advanced structure. And the writer calculates the empirical projects' wind-loads by Chinese code, American standard and British standard, compares the difference and points out the deficiency of domestic code. So as to improve the designers to master different wind load standards and promote the improvement of inland standard.

Contributions of wind-induced overall and local behaviors for internal forces in cladding support components of large-span roof structure

Internal forces in cladding support components of large-span roof structures under wind loads were usually estimated only based on the local wind loads imposed on tributary areas. However, internal forces on such members depend not only on local behaviors caused by local wind loads but also on wind-induced overall behaviors of main structural frames. By ignoring the contribution of overall behaviors of main structural frames, internal forces in cladding support components may be underestimated following current wind load codes or recommendations. It is necessary to investigate the contributions of local and overall behaviors to improve the wind-resistant design of the cladding support component members on large-span roof systems. In this paper, a method was proposed to separate the internal forces of cladding support components due to wind-induced local and overall behaviors and investigate the corresponding contributions for the largest internal forces. Wind loads used for loading effects estimation were obtained based on wind pressures measured from a 1:400 scaled roof model under a boundary layer wind flow configuration. Wind loading effects considering wind-induced total behaviors (overall behaviors and local behaviors together) for axial force, bending moment and shear force were calculated by time-history analysis using finite element (FE) models of the prototype structure. Meanwhile, internal forces in cladding support components only considering local behaviors were extracted by using local wind loads based on quasi-static assumption. Finally, based on the contributions to the largest wind-induced internal forces resulting from the proposed method, a procedure for remedying the current wind load codes for such members were discussed.