Partha P. Sarkar

Department of Aerospace Engineering, Iowa State University, USA

Advances in Simulations to assess Non-Synoptic Wind Effects on Structures

Non-Synoptic windstorm (NSW) events (tornado/downburst/gust-front) cause severe structural damage and numerous fatalities every year in many countries including the United States, where this type of hazard is particularly severe. These events of moderate intensity can produce wind gusts exceeding 50 m/s, whereas tornadoes of highest intensity can produce wind gusts of 90 m/s or more. Damage to infrastructure is expected to increase with growing urbanization and increased intensification/frequency of such windstorms because of climate change. At present, civil structures are designed to resist only straight-line winds associated with a neutrally stable Atmospheric Boundary layer (ABL). The velocity fields in the NSW phenomena are three dimensional and the structural loading they produce is transient in nature and larger in magnitude because of atmospheric pressure change. This lecture reviews the advances in laboratory simulation, numerical modeling and data analysis techniques and tools used for assessing wind hazards to structures in NSW events. Tools such as system identification, time-domain aerodynamic/aeroelastic models, CFD and interactive FEM are used in combination with physical simulations in NSW laboratory simulators to assess structural loads, response, and damage. Advances in these simulations over these past two decades have increased our understanding of near-ground wind in NSW events and their wind loading effects on structures. Effects of parameters influencing wind loads are presented along with examples of mitigation measures that can be taken to reduce the risk to structural damage from NSW windstorms.