Using Tornado Damage Surveys to Improve Laboratory Tornado Simulations

Laboratory tornado simulators, intended for estimating tornado-induced wind loading on structures, have been in development for a little more than ten years with the first such facility being developed at Iowa State University. The ideal validation of such facilities would compare pressures on buildings in the lab to pressures on buildings in the field. Since this is nearly impossible from a practical standpoint, other validations must be sought. In the past, the Iowa State facility's performance has been compared with Doppler radar velocity profiles, with surface pressure profiles and with damage patterns for individual structures. This paper summarizes how the simulator's results compare with the newly acquired damage data from the Moore, Oklahoma tornado of May 21, 2013. The data from this tornado consists of geo-located, structural damage data. The structural damage was plotted as a function of radial distance from the center of the damage path. This function was then compared with lab simulator estimates of how tornado-induced forces vary with distance from the center of the vortex. The lab simulator over-predicted the damage for most radial positions, but the analysis highlights the promise of the lab simulation. The shape of the curves was reasonably consistent and could be improved with a more rational connection between predicted forces and resulting damage.