Computer Modeling of the Influence of Structure Plan Areas on Tornado Forces

<p>The study of the conventional Straight Line (SL) wind flow dominates research into wind loads on structures. Most structure design takes into account only research into SL flow. Few researchers have studied tornado forces on buildings and attempted to distinguish between tornadic wind loads and SL flow loads. Using a computer simulation, this research addresses and distinguishes between the tornadic forces and SL forces on structures. In the numerical simulation, tornado forces and SL forces will be compared on large structure plan areas and on thin structure plan areas. Additionally this research investigates how the increase in the vortex strength (α) affects tornado forces on a cubic structure. The large structure plan areas are dimensionalized by the structure height: (1h x 1h, 2h x 2h, 4h x 4h and 8h x 8h) where h is 20.3 (m) and tornado maximum radius (rmax) is 61(m). The structure plan areas are a multiple of factor two. The thin structure plan areas are obtained by dividing the large structure plan areas by a factor of ten.</p> <p>This research has three key findings. First, when the same maximum reference velocity (Vtrans.) was used and when the large structure plan area characteristic length was approximately twice the tornado maximum diameter, the force and pressure coefficients had the same values as Straight Line (SL) flow. Second, the thin structure plan areas are more likely collapse faster in the presence of a tornado compared to SL flow due to the high differentials pressure in tornado between the windward wall and the leeward wall. In addition, on the thin structure plan areas, the tornado force coefficients were twice the SL flow force coefficients. The final key finding is that when the vortex strength (α) increased, the tornado force coefficients increased exponentially.</p>

Name thesis:degree_name

Doctor of Philosophy in Engineering (PhD)

Level thesis:degree_level

Dissertation

Year dc:date.available

2012

Author dc:creator

• Alrasheedi, Nashmi Hassan M

Advisor dc:contributor.advisor

• Selvam, R. Panneer

Contributors dc:contributor

• Couvillion, Rick J.
• Nutter, Darin W.

• Applied sciences
• Les
• Straight line wind
• Structure plan areas
• Tornado forces
• Computer-Aided Engineering and Design
• Structural Engineering

Repository record dc:identifier

https://scholarworks.uark.edu/etd/317

OAI identifier oai:identifier

oai:scholarworks.uark.edu:etd-1316