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CONTENTS
Volume 37, Number 2, August 2023 (Special Issue)
 

Abstract
This editorial summarizes the scope of a Special Issue aimed to examine the current stateof-the-art and practice associated with the wind engineering load and design standards. Contributions address the major wind design standards around the world. Specifically, the contributions deal with recent developments in the field of codification with emphasis on new technologies, experimental methods and advances in computer simulations that could serve as an additional resource for the designer. Several wind engineering design standards have been recently updated or are currently under major revision because of the recent developments in the wind engineering field. Some examples are: EuroCode 1 – Part 1-4, ASCE 7-22, Australian/New Zealand Standards AS/NZS1170.2, Japanese Building Codes (AIJ, BCJ, etc.) and the Chinese National Standard for Wind Loads. For instance, in ASCE-7 22 a new chapter describes, for the first time, the design against tornado wind hazards. In the revised Australian/New Zealand Standard AS/NZS 1170.2:2021 a profile and topographic multipliers are included for a special region, dominated by downburst winds from thunderstorms. The latest versions of codes and standards for windsensitive structures also include wind loads for special structures such as bridges, lattice towers, offshore platforms and wind-turbines support towers. This Special Issue contributes to the aims of the Journal of Wind and Structures and focuses on invited papers that either contribute to the advancement of the state-of-the-practice in wind load codification or provide a review of one or more standards. Papers selected for the Special Issue are examples of leading research and best practices in the field of wind load analysis and design. The selected studies include analysis of novel design formulas, extreme value analysis of wind speed and direction by collection of new data sets, experimental and computational methods specifically aiming at wind load codification. The selected contributions are selected from experts in each sub-field and discuss either a specific topic or a specific standard. Each selected paper was carefully and thoroughly reviewed by anonymous Reviewers, who are also experts in each field, prior to publication. Adhikari and Letchford (2023) studied wind speed data from Nepal and adjoining countries and examined extreme wind speed climatology for the region. Wind speed information for Nepal was adopted from the Indian National Standard and applied to two orographically different regions: above and below 3000 m elevation respectively. Comparisons of the results were based on relevant codes and standards. Bruno et al. (2023) investigated several design codes and standards, covering the use of Computational Wind Engineering and Computational Fluid Dynamics for wind-sensitive structures and built environment. Special attention was devoted to the findings of the Special Interest Group on Computational Wind Engineering of the Italian Association for Wind Engineering (ANIV-CWE). The same group is currently advising UNI CT021/SC1 in supporting the drafting of new Annex K of the revised Eurocode 1 – Part 1-4 on wind actions. Finally, the study discusses avenues open to future development at technical and practical levels. Holmes et al. (2023) investigated the latest revision of AS/NZS 1170.2 that incorporates new research and knowledge on strong winds, climate change, and shape factors for new structures of interest such as solar panels. Australia and New Zealand cover climatic zones from tropical to cold temperate, and virtually every type of extreme wind event: gales from synoptic-scale depressions, convectively-driven downdrafts from thunderstorms, tropical cyclones, downslope winds, and tornadoes. A 'climate change multiplier' was included and several modifications for the structural analysis of solar panels, curved roofs, poles and masts, high-rise buildings and other dynamically wind-sensitive structures. Kopp (2023) discusses the substantive changes to the ASCE 49-21 Standard "Wind Tunnel Testing for Buildings and Other Structures". The most significant changes are the requirements for wind field simulations that utilize (i) partial turbulence simulations, (ii) partial model simulations for the flow around building appurtenances and requirements for determining wind loads on items at multiple sites and in various configurations. Modifications were implemented to allow constructing models for small elements placed on large buildings at the scales typically available in boundary layer wind tunnels. The study also examines research needs with respect to aerodynamic mechanisms, the role of turbulence on separatedreattaching flows on building surfaces, etc. Lee et al. (2023) analyzed the Korean Design Standard (KDS) that will be updated with two major revisions on the assessment of wind load and performance-based wind design (PBWD). Major changes on the wind load assessment are the wind load factor and basic wind speeds. Additional modifications include pressure coefficients, torsional moment coefficients, spectra, and aeroelastic instability. PBWD is a newly added section in the KDS. Ricciardelli (2023) examined the new EN 1991-1-4 Eurocode 1 – Part 1-4 on wind actions. The papr summarizes the work of the project team from August 2017 to April 2020. The document includes several modifications and new sections: updated design wind maps, improved wind models, updated force and pressure coefficients, review of procedures for evaluating dynamic response. Personal recommendations by the Author are also discussed. Wang et al. (2003) compared the "Code of Practice on Wind Effects in Hong Kong" of 2019 with the latest revision of the Architectural Institute of Japan (AIJ) Recommendations for Loads on Buildings, and the Australian/New Zealand Standard, AS/NZS 1170.2:2021. Comparisons include design wind speeds, profiles and wind speed multipliers. The study also highlighted differences in the basic design wind speed and exposure factor estimation, together with future development trends.

Key Words


Address
Luca Caracoglia: Northeastern University
John D. Holmes: JDH Consulting

Abstract
This paper traces the drafting of the new EN 1991-1-4 Eurocode 1 – Actions on structures - Part 1-4: General actions - Wind actions within Mandate M/515 of the European Commission to CEN, for the evolution of structural Eurocodes towards their Second Generation. Work of the Project Team started in August 2017 and ended in April 2020, with delivery of a final draft for public enquiry. The revised document contains several modifications with respect to the existing 2005 version, and new sections were added, covering aspect not dealt with in the previous version. It has a renovated structure, with a main text limited in size and containing only fundamental material; all the remaining information, either normative or informative is arranged into thirteen annexes. Common to other Eurocode Parts, general requests from CEN were those of reducing the number of Nationally Determined Parameters and of enhancing the ease of use. More specific requests were those of (a) the drafting of a European design wind map, (b) improving wind models, (c) reviewing force and pressure coefficients, (d) reviewing the procedures for evaluation of the dynamic response, as well as (e) making editorial improvements aimed at a more user friendly document. The author had the privilege to serve as Project Team member for the drafting of the new document, and this paper brings his personal view concerning some general aspects of wind code writing, and some more specific aspects about the particular document.

Key Words
Eurocodes; structural reliability; wind loading codes; wind loads

Address
Francesco Ricciardelli:Department of Engineering, University of Campania "Luigi Vanvitelli", via Roma 29, 81031 Aversa (CE), Italy

Abstract
The latest revision of AS/NZS 1170.2 incorporates some new research and knowledge on strong winds, climate change, and shape factors for new structures of interest such as solar panels. Unlike most other jurisdictions, Australia and New Zealand covers a vast area of land, a latitude range from 11° to 47° S climatic zones from tropical to cold temperate, and virtually every type of extreme wind event. The latter includes gales from synoptic-scale depressions, severe convectively-driven downdrafts from thunderstorms, tropical cyclones, downslope winds, and tornadoes. All except tornadoes are now covered within AS/NZS 1170.2. The paper describes the main features of the 2021 edition with emphasis on the new content, including the changes in the regional boundaries, regional wind speeds, terrain-height, topographic and direction multipliers. A new 'climate change multiplier' has been included, and the gust and turbulence profiles for over-water winds have been revised. Amongst the changes to the provisions for shape factors, values are provided for ground-mounted solar panels, and new data are provided for curved roofs. New methods have been given for dynamic response factors for poles and masts, and advice given for acceleration calculations for high-rise buildings and other dynamically wind-sensitive structures.

Key Words
Australia; New Zealand; standard; wind load; wind speed

Address
John D. Holmes: JDH Consulting, PO Box 269, Mentone, Victoria, 3194, Australia

Richard G.J. Flay:Department of Mechanical and Mechatronics Engineering, University of Auckland, New Zealand

John D. Ginger:College of Science and Engineering, James Cook University, Townsville, Queensland, Australia

Matthew Mason:School of Civil Engineering, University of Queensland, Brisbane, Queensland, Australia

Antonios Rofail:Windtech Consultants, Bexley, New South Wales, Australia

Graeme S. Wood:Arup Group, Sydney, New South Wales, Australia

Abstract
Structural design includes calculation of the wind speed as one of the major steps in the design process for wind loading. Accurate determination of design wind speed is vital in achieving safety that is consistent with the economy of construction. It is noticeable that many countries and regions such as Hong Kong, Japan and Australia regularly make amendments to improve the accuracy of wind load estimations for their wind codes and standards. This study compares the latest Hong Kong wind code published in 2019, which is generally known as the Code of Practice on Wind Effects in Hong Kong - 2019, with the latest revision of the AIJ Recommendations for Loads on Buildings - 2015 (Japan), and the Australian/New Zealand Standard, AS/NZS 1170.2:2021. The comparisons include the variations between the design wind speed and the vertical profiles of wind speed multipliers. The primary purpose of this study was to show any differences in the basic design wind speed and exposure factor estimations among the three economies located in the Western Pacific Ocean. Subsequently, the reasons for such underlying variations between the three documents, are discussed, together with future development trends.

Key Words
basic design wind speed; exposure factor; new revision; wind loading code

Address
Jiayao Wang, Tim K.T. Tse and Tsz Kin Chan:Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology,
Clear Water Bay, Kowloon, Hong Kong

Sunwei Li:Shenzhen International Graduate School, Tsinghua University, Shenzhen, China

Jimmy C.H. Fung:Department of Mathematics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong

Abstract
Korea Design Standard (KDS) will be updated with two major revisions on the assessment of wind load and performance-based wind design (PBWD). Major changes on the wind load assessment are the wind load factor and basic wind speed. Wind load factor in KDS is reduced from 1.3 to 1, and mean recurrence interval (MRI) for basic wind speed increases from 100 years to 500 years considering the reduction of wind load factor. Additional modification is made including pressure coefficient, torsional moment coefficient and spectrum, and aeroelastic instability. Combined effect of the updates of KDS code on the assessment of wind load is discussed with the case study on the specified sites and building. PBWD is newly added in KDS code to consider the cases with various target performance, vortex-induced vibration, aeroelastic instability, or inelastic behavior. Proposed methods and target performance for PBWD in KDS code are introduced.

Key Words
basic wind speed; KDS code; performance-based wind design; wind load reduction factor; wind load

Address
Han Sol Lee, Seung Yong Jeong and Thomas H.-K. Kang:Department of Architecture and Architectural Engineering & Institute of Engineering Research, Seoul National University,
1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea

Abstract
This paper first provides a wide overview about the design codes and standards covering the use of Computational Wind Engineering / Computational Fluid Dynamics (CWE/CFD) for wind-sensitive structures and built environment. Second, the paper sets out the basic assumptions and underlying concepts of the new Annex T "Simulations by Computational Fluid Dynamics (CFD/CWE)" of the revised version "Guide for the assessment of wind actions and effects on structures" issued by the Advisory Committee on Technical Recommendations for Constructions of the Italian National Research Council in February 2019 and drafted by the members of the Special Interest Group on Computational Wind Engineering of the Italian Association for Wind Engineering (ANIV-CWE). The same group is currently advising UNI CT021/SC1 in supporting the drafting of the new Annex K – "Derivation of design parameters from wind tunnel tests and numerical simulations" of the revised Eurocode 1: Actions on structures – Part 1-4: General actions – Wind actions. Finally, the paper outlines the subjects most open to development at the technical and applicative level.

Key Words
best practices; codes and standards; Computational Wind Engineering; Eurocode PrEN 1991-1-4:2021–Annex K; Guide CNR-DT 207-R1/2018-Annex T

Address
Luca Bruno:1)Department of Architecture and Design, Politecnico di Torino, viale Mattioli 39, 10131 Torino, Italy
2)Special Interest Group in Computational Wind Engineering (ANIV-CWE),Italian Association for Wind Engineering

Nicolas Coste:1)2Optiflow Company, 160 Chem. de la Madrague-Ville, 13015 Marseille, France
2)Special Interest Group in Computational Wind Engineering (ANIV-CWE),Italian Association for Wind Engineering

Claudio Mannini:1)3Department of Civil and Environmental Engineering, University of Florence, Via di Santa Marta, 3 – 50139 Firenze, Italy
2)Special Interest Group in Computational Wind Engineering (ANIV-CWE),Italian Association for Wind Engineering

Alessandro Mariotti:1)Department of Civil and Industrial Engineering, University of Pisa, Largo Lucio Lazzarino, 2 – 56122 Pisa, Italy
2)Special Interest Group in Computational Wind Engineering (ANIV-CWE),Italian Association for Wind Engineering

Luca Patruno:1)Department of Civil, Chemical, Environmental, and Materials Engineering, Viale del Risorgimento 2, 40126 Bologna, Italy
2)Special Interest Group in Computational Wind Engineering (ANIV-CWE),
Italian Association for Wind Engineering

Paolo Schito:1)Department of Mechanical Engineering, Politecnico di Milano, via La Masa 1 - 20156 Milano, Italy
2)Special Interest Group in Computational Wind Engineering (ANIV-CWE),Italian Association for Wind Engineering

Giuseppe Vairo:1)Department of Civil Engineering and Computer Science, University of Rome

Abstract
Wind speed data from Nepal and adjoining countries have been analyzed to estimate an extreme wind speed climatology for the region. Previously wind speed information for Nepal was adopted from the Indian National Standard and applied to two orographically different regions: above and below 3000 m elevation respectively. Comparisons of the results of this analysis are made with relevant codes and standards. The study confirms that the assigned basic wind speed of 47 m/s for the plains and hills of Nepal (below 3000 m) is appropriate, however, data to substantiate a basic wind speed of 55 m/s above 3000 m is unavailable. Using a composite analysis of 15 geographically similar stations, the study also generated 435 years of annual maxima wind data and fitted them to Type I and Type III extreme value distributions. The results suggest that Type III distribution may better represent the data. The findings are also consistent with predictions made by Holmes and Weller (2002) and to a certain extent those of Sarkar et al. (2014), but lower than the analysis undertaken by Lakshmanan et al. (2009) for northern India. The study also highlights that the use of a load factor of 1.5 on wind load implies lower strength design MRI' s of around 260 years compared to the 700 years of ASCE 7-22.

Key Words
extreme winds; orography; wind climatology

Address
Manoj Adhikari and Christopher W. Letchford:Department of Civil and Environmental Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA

Abstract
The paper reviews and discusses the substantive changes to the ASCE 49-21 Standard, Wind Tunnel Testing for Buildings and Other Structures. The most significant changes are the requirements for wind field simulations that utilize (i) partial turbulence simulations, (ii) partial model simulations for the flow around building Appurtenances, along with requirements for determining wind loads on products that are used at multiple sites in various configurations. These modifications tend to have the effect of easing the precise scaling requirements for flow simulations because it is not generally possible to construct accurate models for small elements placed, for example, on large buildings at the scales typically available in boundary layer wind tunnels. Additional discussion is provided on changes to the Standard with respect to measurement accuracy and data acquisition parameters, such as duration of tests, which are also related to scaling requirements. Finally, research needs with respect to aerodynamic mechanisms are proposed, with the goal of improving the understanding of the role of turbulence on separated-reattaching flows on building surfaces in order to continue to improve the wind tunnel method for determining design wind loads.

Key Words
atmospheric boundary layer; building aerodynamics; partial turbulence simulation; wind loads; wind tunnel methods

Address
Gregory A. Kopp:Boundary Layer Wind Tunnel Laboratory, Faculty of Engineering, Western University, London, ON, Canada

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