Performance-based wind engineering framework for vertical structures subjected to nonstationary wind loads

Abstract

Regarded as a rational analytical approach that enables more risk-informed decision making, performance-based engineering (PBE) has been widely endorsed by the wind engineering community for the design and analysis of vibration-sensitive structures such as tall buildings. Accomplished through modular stages that delineate a structure's capacity to satisfy performance objectives, the uncertainties, error propagation, and random properties of the structural system, the environmental hazard, and the estimation of losses incurred from damages can be systematically examined with great detail. This multi-faceted, holistic approach combines this information to better equip engineers, owners, and stakeholders with the knowledge to reduce wind-induced damage risks. In the current day, performance-based wind engineering (PBWE) has been substantially refined, especially for synoptic phenomena such as hurricanes and extratropical depressions. However, it is still largely deficient in one regard: the consideration of short-duration, non-synoptic, rapidly evolving thunderstorm downbursts and tornadoes. These windstorms have been mostly neglected in the development of the performance-based methodology because of the incomplete knowledge surrounding the hazard probability definition and the fluid-structure forces that they impart on structures. Their nonstationary, evolutionary properties run counter to the simplifying assumptions conventionally adopted in wind engineering. Research is ongoing to more fully understand downbursts and tornadoes, and consequently, the efforts to apply PBWE for the analysis of these nonstationary wind phenomena have been severely lacking. The purpose of this dissertation is to fill this gap in the developing field of PBWE and outline a framework to evaluate the performance metrics, wind-induced damages, and resulting consequences of vertical structures subjected to downburst and tornado loads. Risks are calculated with information gathered from physical experimentation and numerical simulations. Results are used to examine the accumulation of intervention costs related to failure of specified performance objectives, i.e. in terms of life-cycle cost assessment. Key components of the methodology including fragility, hazard, and loss analyses are tailored in the computational framework for the separate consideration of downbursts and tornadoes. Ultimately, this will further advance PBWE, extending its application beyond synoptic wind phenomena.--Author's abstract