Performance-Based Wind and Seismic Engineering: Benefits of Considering Multiple Hazards

This paper discusses the benefits of performance-based seismic and wind design, including allowing controlled limited yielding under wind loads. For tall buildings in earthquake prone regions, it is often found that the design of certain structural elements (e.g. buckling-restrained brace outriggers) is controlled by wind demands, forcing these elements to be stronger or stiffer than would otherwise be required to meet seismic design objectives. These wind controlled elements can start a chain reaction, wherein the element size is increased for wind demands, which results in a stiffer element and therefore greater seismic demands. The seismic performance and economy are further hindered by the necessary seismic design principles of controlled yielding and capacity design, where increasing the size of energy dissipating elements tends to produce a cascading detrimental effect upon columns, diaphragms, foundations, connections, and other structural elements. In recent years, proposals have been put forward to extend the performance-based framework to wind engineering, with thus far limited implementation due to technical, practical, and jurisdictional challenges. This paper will further express the relevance and state of practice in combined hazard performance-based design.