Standards Development

Scope

Standardization in the field of performance-based wind design (PBWD) of concrete buildings, including, but not limited to, terminology, PBWD framework, inelastic wind design, hazard analysis, performance objectives and criteria, artificial time history generation, application of wind load reduction factor, elastic and inelastic analysis procedure.

Purpose

Wind loads are critical lateral loads for design of structures. The current perspective for design of structure for wind load is based on elastic behavior under both service and factored (ultimate) loads. Despite the advantages and ease of use of this procedure, some drawbacks necessitate an alternative design approach. First of all, the code-based design procedure cannot guarantee to meet the target reliability set by stakeholders. Performance-based design can be effectively used to evaluate actual performance of structure under each level of load. Another issue is related to a conflict between philosophy of wind design (based on elastic behavior) and seismic design (based on inelastic behavior). In case where wind load is dominant for strength of structure or some elements (usually happens in high-rise buildings), it results in larger overstrength and capacity than required for seismic load. This overdesign of fuse elements such as coupling beams and braces leads to a failure of joints and vertical members (i.e., a brittle behavior) under strong seismic loads. To solve this problem, PBWD (especially inelastic wind design) has been discussed recently by wind researchers and practicing engineers. Though behavior under service load should be essentially elastic due to philosophy of serviceability design, lack of knowledge for inelastic behavior under wind action is one of the main reasons behind elastic design for ultimate load. Therefore, by improving knowledge about inelastic behavior of structure under wind load, inelastic behavior can be permitted to eliminate the conflict. These issues motivated the wind and structural engineering community to develop a framework for performance-based wind design (PBWD) for more reliable and cost-effective design.

Performance-based seismic design (PBSD) has been developed in many aspects during last decades through experimental, analytical, and probabilistic studies. However, framework for PBWD is still under development and many parameters are not clarified. Significant knowledge and information for PBSD cannot be directly utilized for PBWD, because of different nature of wind and seismic load.

Investigation of damage accumulation in along-wind direction and low-cyclic fatigue in across-wind direction are two examples that are not checked for members which are designed for seismic load and needs more studies to evaluate performance of members under such conditions.

Currently, there are few standards or guidelines for PBWD. ASCE 7-22 permits PBWD with very brief explanation. ASCE presetandard for PBWD provides very detailed explanation for PBWD, but it requires great knowledge about probabilistic approach which makes it very complex to be used by engineers and also it does not provide a procedure for inelastic wind design. Because of the complexity in probabilistic PBWD, it may not be followed for actual design of normal buildings. The latest revision of Korean Design Standard (KDS 41:2022) permits PBWD and provides some basic information for inelastic wind design. None of the mentioned references provide information for design of components. The proposed international standard aims to provide a guideline to perform PBWD and inelastic wind design for concrete buildings with a simplified procedure. It has the potential to assist structural engineers, wind engineers, and construction companies to overcome the mentioned inconsistencies and design more cost-effective concrete buildings through a simplified PBWD procedure.

The proposed project leader, Prof. Thomas Kang, has many contributions, experiences, and publications in the field of concrete structures, earthquake and wind engineering, and performancebased seismic and wind design in both national and international projects and technical committees. He also contributed in the development of PBWD and inelastic wind design sections in KDS 41:2022 draft. The knowledge and experiences of the proposed leader make him capable to provide the proposed international standard to facilitate PBWD and inelastic wind design of concrete structures for practical projects.