Abstract:
Hurricane-induced losses have grown from $1.3B/yr pre-1990 to $36B/yr post-2000. The losses surpassed $100B in 2005 and caused over 1,400 fatalities in 2004-05. Computational and experimental approaches focusing on the complex interaction between hurricanes and the built environment are therefore necessary to develop comprehensive and systemic mitigation strategies to build resilient communities. The mitigation solutions are aimed at new buildings as well as retrofitting existing ones and will satisfy some basic sustainability constraints which are sometimes in contradiction with each other. Due to complex interactions of environmental turbulent (wind) flows within the built environment and their multi-scale nature spanning over large time and length scales, there are gaps in numerical approaches hindering their practical use for assessing wind performance of the built environment. This study proposes a multi-scale numerical approach comprising of (i) large scale (boundary condition characterization), (ii) medium scale (study building and its immediate surrounding) and (iii) high resolution small scale internal flows. The seminar will present preliminary results of computational efforts focusing on the characterization of upcoming wind flow over different upstream terrain conditions (including complex topography such as mountain-valley systems, roughness created by urban and suburban terrain) and the evaluation of wind loads on buildings. The adopted approach uses a computational fluid dynamics (CFD) as well as its validation by comparison with BLWT or Wall of Wind experimental data. Once the multi-scale numerical models have been validated, reduced order models will be used either to develop mitigation strategies or for educational purposes. These tools are beneficial for sustainable design applications such as natural ventilation as well.

Biography:
Girma Bitsuamlak is an assistant professor at the Civil and Environmental Engineering department with a joint appointment with International Hurricane Research Center at FIU. His current research interests include enhancing built environment's resiliency to natural disasters such as hurricane under the constraints of sustainability through computational wind engineering and/or full (model)-scale experiments by using "Wall of Wind". On the computational side, he has studied the effect of topography on design wind loads and wind load evaluation for buildings. He has performed special studies on complex terrain upstream exposure, for which no building code provisions exist. On the experimental side, he has been instrumental in the development of a full-scale hurricane wind and wind-driven rain testing facility, the "Wall of Wind" at FIU. While working with RWDI Inc. he has performed aeroelastic model studies for special projects including the Freedom Tower in New York and Burj-Dubai in Dubai. He has executed close to 100wind load and response studies for tall buildings and large span roofs for projects scattered around the world. He has recently received a prestigious NSF CAREER award for a project titled "Multi-scale computational evaluation of wind load on buildings".