Design Wind Speed Research Articles

Multivariate Distributions with Specified Marginals: Applications to Wind Engineering

Bounds on and approximations of the distribution of a non-Gaussian vector X specified partially by the marginal distributions Fi of its coordinates Xi or the marginal distributions Fi and some information on the correlation structure of X are developed. These results are used to: (1) bound and approximate the distribution of the largest coordinate of X, that is, the random variable Y=maxi{Xi}; and (2) evaluate current practice in wind engineering based on models for directional and directionless wind speeds (that is, yearly maximum wind speeds recorded in several directions and irrespective of direction) that are postulated independently of each other. It is shown that, although current directional and directionless wind speed models are inconsistent with probability theory, they can deliver similar design wind speeds if calibrated to very long wind speed records but their predictions can differ significantly if based on typically available records.

Tropical Cyclone Larry: Estimation of Wind Field and Assessment of Building Damage

SummaryTropical Cyclone Larry made landfall on 20 March 2006 near Innisfail, causing significant damage to buildings in the surrounding areas. This paper is based on the field survey and assessment of the performance of buildings, which experienced severe winds in the Innisfail region during Tropical Cyclone Larry. The peak gust wind speeds in the study area are estimated at 50 to 65 m/s, which is less than the region’s current design wind speed. Damage to the housing stock was estimated at about 20% (not including water ingress). Contemporary housing fared considerably better than older housing, reflecting marked improvement of construction detailing and better structural condition, and satisfactory performance of relevant standards. Failure of roller doors, loss of roof battens when fastened to rafters with one or two nails, and loss of rafters or trusses when anchored to top plates with skew nails only, were common. Structural component failures of under-designed cold-formed steel sheds and garages were also widespread. Construction details used in houses on or near hill-tops need to reflect the higher wind speed caused by topographic effects.

A Study on the Wedge Angle of the Rail Clamp according to the Design Wind Speed Criteria Change

In cargo-working, it unavoidably happens that the quay crane slip along the rail and the container move from side to side. Especially, they involve a lot of risk in bad weather. The rail clamp is a mooring device to prevent that the quay crane slips along the rail due to bad weather or the wind blast while the quay crane do the cargo-working And it will play a greater role in port container terminal integration and automation To design the wedge type rail clamp, it is very important to determine the wedge angle. In this study, we expect that the design wind speed of the quay crane will change over 16m/s. Assuming that the design wind speed is 40m/s, we determined the proper wedge angle of the wedge type rail clamp for the 50ton class quay crane.

Reliability and code level

The paper describes the work of the IAWE Working Group WBG - Reliability and Code Level, one of the International Codification Working Groups set up at ICWE10 in Copenhagen. The following topics are covered: sources of uncertainties in the design wind load, appropriate design target values for the exceedance probability of the design wind load for different structural classes with different consequences of a failure, yearly exceedance probability of the design wind speed and specification of the design aerodynamic coefficient for different design purposes. The recommendations from the working group are summarized at the end of the paper.

Lateral loading and response for a tall building in the non-seismic doldrums

The situation for building design against wind and earthquake effects in Singapore is apparently unique. There is no seismic design code as there is no local seismicity, yet the effects of significant regional earthquakes are frequently felt in many high rise buildings in Singapore. Whereas it has become clear that the strongest winds in Singapore originate from storms and squalls, design for wind by law requires use of an arbitrary design wind speed applied in a British loading code geared to cyclonic wind systems. A decade of monitoring of a 280 m office tower has shown that distant strong earthquakes generate dynamic response typically an order of magnitude greater than due to the strongest winds occurring during the same period. The effect is greater for high rise apartment blocks and it is becoming clear that for extreme events with similar return periods, earthquake effects should govern design for lateral load in terms of dynamic base shears under such conditions. For the present, building control authorities take code provisions for accidental eccentricity to be adequate in covering seismic loads. While there have been moves towards a more rational local code, there remains an open question about the relationship of static and dynamic effects due to wind for both cyclonic and (thunder)storm winds. In this paper, the evidence concerning the nature of the two forms of loading is presented, and the various existing and potential code provisions examined.

A comparison of methods of extreme wind speed estimation

The paper presents a comparative assessment of methods for extreme value analysis of the US wind speed data using four different methods, namely Standard Gumbel, Modified Gumbel, Peaks-Over-Threshold (POT) and Method of Independent Storms (MIS). The analysis highlights the influence of methodological assumptions on the estimates of design wind speed corresponding to 50-year and 500-year return period. The results demonstrate that the MIS method leads to more stable quantile estimates than the POT method.

Second Nanjing Cable-Stayed Bridge

The Second Nanjing cable-stayed bridge over the Yangtze river, China is 11 km downstream from the first Nanjing bridge and passes through Baguazhou, the third largest island in the Yangtze river. The main bridge in the southern section is a cable-stayed bridge with five continuous spans of steel box girder with an orthotropic deck and an epoxy asphalt concrete pavement. The main span is 628 m long. The technical specifications are listed: deck width, design speed, design load, design wind speed, ship collision force, navigational clearance, design flood frequency, deck slope and seismic scale. The design and construction of the deep water foundation of the tower, the reinforced concrete cable tower and main girder are described. The zinc-plated steel cables and their installation are described.

Reliable Design Loads for Natural Phenomena: Illustration with Wind Speeds

A primary purpose of structural codes is to provide designs that produce safe and economical structures for their entire intended lifetime. When considering forces due to natural phenomena, our historical records are often marginal in terms of reliable data. This is especially true for the case of wind loads, where topography effects prevent the use of historical data except in the local region. Therefore, one may need to select wind forces based on a 50- or 75-year design life when the total record length is of that magnitude. The field of extreme value statistics is a powerful methodology that has not had significant use by the engineering community. It is specifically intended to provide the most reliable estimates for return periods of the order of the total record length. In this study, automatically recorded wind data from several sites in the Pacific Northwest region of the United States are used to provide design wind speeds. These speeds are compared with the raw data to indicate the sensitivity of the procedures. Extreme sensitivity of the design wind speeds is found, dependent on which probabilistic method is used to compute them. Use of design data from observed extremes, fitted probabilistic models, and extreme value statistical theory give very different results between sites and even within sites. Great caution is needed for design values longer than the observed data record, and even for return periods on the order of the length of the data record. While the paper uses the recorded wind data as a pathfinder, the approach is discussed in terms of the determination of design loads for other natural phenomena.

Typhoon Simulation incorporating Effects of Sea-Surface Temperature

Large-scale and/or long-span structures, which must be sustained for long service life, are susceptible to strong winds. Their design wind speeds are mostly decided by typhoons in Japan. Global warming typically causing the increase of the sea-surface temperature would affect, probably intensify typhoons approaching Japan. In order to investigate the effects of the increase of the sea-surface temperature on typhoon frequency and intensity, a new typhoon simulation technique was developed incorporating the sea-surface temperature. The new simulation technique predicted future trends due to the increase of the sea-surface temperature that the number of typhoon approaching Japan increased and depression of the central pressure increased. It was also shown that 100-year recurrence wind speeds in 24 regions in Japan increased by 10 - 15% on the average due to future increase of the sea-surface temperature.

Determining Design Wind Loads for Work Zone Traffic-Control Devices

Proper traffic control and delineation are critical to achieving safety in work zones. In addition to being crashworthy, a barricade or temporary sign support should have the ability to withstand anticipated service loads. If a barricade or temporary sign support fails or overturns, it cannot perform its intended function and the safety of the work zone may be compromised. Currently, no guidance is provided on the service loads that should be used in the design of these work zone devices. Recommendations are provided for design wind loads for work zone traffic-control devices. The results from field trials indicate that truck-induced wind loading is not a critical design issue for barricades and barricades with signs. The recommendations are thus based on an analytical determination of design wind speeds associated with different recurrence intervals that correspond to the duration of work zone activities. Analytical case studies are presented for two common barricade designs, with consideration given to both structural capacity and overturn. Guidance on the amount of ballast required to prevent overturn is provided as a function of wind speed, barricade length, and sign mounting height.

Studies on Wind Resistant Design Using the Directional Basic Wind Speed

Transmission towers are considered to be designed with enough wind-resistant performance, however, it is necessary to re-examine the current estimation methods from both points of design wind speed and wind load to rationalize the tower design and to improve the structural integrity. Wind resistant rationalization committee (FY1999-FY2001), organized by Central Research Institute of Electric Power Industry (CRIEPI), promoted the studies on directional basic wind speed and equivalent static wind load estimation following the previous committee on wind resistant design method for local winds effected by topography (FY1992-FY1998). The purpose of this paper is to describe the summary of the investigation results of the wind resistant rationalization committee and to show the outline of "Recommendations for wind loads on transmission towers - a draft (2002)".

A STUDY ON DIRECTIONAL BASIC WIND SPEED FOR THE WIND RESISTANT DESIGN OF TRANSMISSION TOWERS

Since the wind load is critical for the design of transmission lines, it is important to assess the design wind speed reasonably at construction sites. Wind loads acting on the transmission tower usually vary greatly by direction because of the structural characteristics. However, in the current design method of transmission towers, non-directional basic wind speed is applied in Japan, and therefore in many cases this may result in overestimation. In this paper, a method to estimate directional basic wind speed for the transmission tower design is proposed. The return period of the directional wind speed is estimated keeping the same non-exceeding probability of occurring stresses as the current design method. Then directional basic wind speeds at meteorological stations are determined by comparing with the typhoon simulation results.

A 100 years of some wind loading provisions in Central and Eastern Europe

This paper deals with the main features of some wind loading provisions in Central and Eastern Europe from the end of the 19th century to present. They are design wind speeds, terrain categories and wind profiles, and gust response factors. Early assumptions and provisions as well as their changes throughout the last century are presented. In this context the influence of Davenport's ideas and works on those provisions are pointed out.

Wind speeds in tropical cyclones and associated insurance losses

This paper reviews the characteristics of wind speeds in tropical cyclones revealed by data from modern automatic weather stations, dropwindsondes, and Doppler radar in the United States. In general winds in tropical cyclones are found to possess the same relationships between surface and gradient speeds as extra-tropical cyclones and the same level of gustiness. Relationships between wind speeds and insurance losses are developed and used to refine the Beaufort Scale. It is shown that statements issued by the National Hurricane Center (NHC), the US government agency responsible for issuing warnings and statements of current and past conditions in tropical cyclones, do not reflect the surface data now available. It is also shown that the design wind speeds in tropical-cyclone-prone areas of the United States, which are based on computer simulations, appear to be unreasonably high in the light of wind speed characteristics presented in this paper and speeds measured in past storms. The findings reported are discussed in the context of information presented in 1963 by Shellard and Davenport in the first major wind engineering conference.

The Correlation Between Extreme Wind and Flood Events in Unregulated River Basins

The aim of this investigation is to improve the method for calculating design wind speed used for wave run up at water reservoirs. It is focused on the relation between extreme flood and wind events, and between wind speed and duration. Water flow data from fourteen Norwegian river basins and wind data from neighbouring airfields are correlated. Some positive correlation is found for areas situated at the coastal side of the mountains where a further analysis is carried out. Extreme value analysis of the wind and flood series provides estimates of T-year events for each of the two variables. The best-fitted equation linking the square of the maximum 10-minute wind speeds to the daily mean water flow is established. It is observed that the expected wind speed during the 1000-year daily flood event has approximately one year return period. The risk for higher wind speed is high, so the effect of adding 1 and 1.65 standard deviations of the maximum wind speed is assessed, increasing the expected return period to 5 and 20 years respectively. Continuous records of 10-minute wind speed are used to establish transfer coefficients from the extreme 10-minute value to durations of 20 minutes to 6 hours.

Bootstrap simulations for evaluating the uncertainty associated with peaks‐over‐threshold estimates of extreme wind velocity

AbstractIn the peaks‐over‐threshold (POT) method of extreme quantile estimation, the selection of a suitable threshold is critical to estimation accuracy. In practical applications, however, the threshold selection is not so obvious due to erratic variation of quantile estimates with minor changes in threshold. To address this issue, the article investigates the variation of quantile uncertainty (bias and variance) as a function of threshold using a semi‐parametric bootstrap algorithm. Furthermore, the article compares the performance of L‐moment and de Haan methods that are used for fitting the Pareto distribution to peak data.The analysis of simulated and actual U.S. wind speed data illustrates that the L‐moment method can lead to almost unbiased quantile estimates for certain thresholds. A threshold corresponding to minimum standard error appears to provide reasonable estimates of wind speed extremes. It is concluded that the quantification of uncertainty associated with a quantile estimate is necessary for selecting a suitable threshold and estimating the design wind speed. For this purpose, semi‐parametric bootstrap method has proved to be a simple, practical and effective tool. Copyright © 2003 John Wiley & Sons, Ltd.

Implications of Typhoon York on the design wind speeds in Hong Kong

There are significant differences between the design wind speeds recommended by the Hong Kong Code-1983 (Code of Practice on Wind Effects, Hong Kong, Building Development Department, Hong Kong, 1983) and those predicted by the Monte-Carlo simulation model (Design wind speeds in tropical cyclone-prone regions, Ph.D. Thesis, The University of Western Ontario, London, Ontario, 1985). The differences are due to the difficulty in determining the ratio of surface to upper-level wind speeds in typhoons, particularly for regions of complex topography. Typhoon York, which struck the Hong Kong area in September 1999 and was the strongest typhoon in that region since 1983, provides an opportunity to revisit the Hong Kong code design wind speeds and the wind field simulation models (e.g., Design wind speeds in tropical cyclone-prone regions, Ph.D. Thesis, The University of Western Ontario, London, Ontario, 1985). In this paper, Boundary Layer Wind Tunnel Laboratory's typhoon model is used to recreate Typhoon York and an alternative approach is developed to model the hurricane boundary layer. The wind speeds and wind direction recorded at different anemometer locations around the Hong Kong area during the passage of Typhoon York are compared with the simulated time histories at these stations. The results show good agreement between the observed and the simulated wind speeds which support lower ratios of upper-level to surface wind speeds than are used in the current Hong Kong code.

Study on evaluation time in typhoon simulation based on Monte Carlo method

A computer simulation based on the Monte Carlo Method has been developed for predicting extreme wind speeds in regions dominated by typhoons. These methods have become the most frequently used tools in estimating design wind speeds for structures and the long-term risk levels arising from these winds. This paper presents refinements of this method, focusing on improvements to the statistical distribution functions describing typhoon characteristics used in the simulation. Two important points are identified. First, the relation between the radius of the maximum wind speed and the central pressure depth can be approximated by index functions. Second, the mean wind speed predicted from the model tends to correspond with the 3 h moving average value of the mean wind speed.

Extreme wind studies in Singapore. An area with mixed weather system

This paper presents an extreme wind studies in Singapore, which is an area with mixed weather systems. The extreme winds in Singapore are generated by both monsoon and thunderstorms (or squalls). Thus, the design wind speed is expected to be influenced by these weather systems. Two methods, i.e. Gumbel's and Independent Storm methods, were used in this study. However, the co-existence of the weather systems suggested that the estimation of the design wind speed might not be done in a straightforward manner. Extreme wind data need to be sorted according to the different wind producing weather system before any analyses could be carried out. In this study, the wind extreme data were separated into two weather systems, namely the large- and small-scale systems. Although the area of Singapore is about 40 km×20 km, the result suggests that the wind characteristics at Tengah (west side of Singapore) were different from Seletar (central) and Changi (east of Singapore).

Reliability analysis of wind response of flexibly supported tall structures

AbstractStatistics and probabilistic analyses and risk assessments can be very useful decision‐making tools when dealing with structural–geotechnical problems. Wind loads, dynamic properties of soil underneath the structure and material characteristics of the structure are important factors that affect the wind action on the structure and consequently the structural wind‐induced response. Uncertainties in the estimation of these factors as a result of human error or inherent variability are at the forefront for the use of reliability approaches to evaluate the risk of failure during the service period. In the present study, probabilistic base force analyses for tall structures are performed. The substructure approach in which the soil supporting the foundation is modeled by the foundation compliances as functions of soil shear wave velocity is used to account for the soil–structure interaction efficiently. A three‐variable probabilistic approach is used to account for the uncertainties in shear wave velocity of the soil underneath the foundation, the concrete strength and the design wind speed on the calculated response and the base forces. The second moment approximation using Taylor series expansion is used to perform the probabilistic analyses of the base cross‐section design and resistant forces of a free‐standing tower. The first‐order reliability method is used to examine the failure probability and the contribution to the total uncertainty. The results show that the dynamic response of the tower increases as soil shear wave velocity decreases. For the range of soil shear wave velocity encountered in practice, the base forces of the structure may increase by up to 20% as a result of the foundation flexibility. For the limit state considered in this study, it was found that the reliability index decreases by up to 15% and the probability of failure increases by up to one order of magnitude as a result of the soil–structure interaction effect. Copyright © 2003 John Wiley & Sons, Ltd.