# Wind Loads on Overhead Sign Structures: A Comparative Study
## 1 Introduction  
The increased sea surface temperature equates to a rise in the probability of wind-related damages [1]. Over the past few decades, the United States has witnessed several catastrophic hurricanes, such as Katrina (2005), Rita (2005), Gustav (2008), Isaac (2012), Nate (2017), Michael (2018), and Laura (2020) [2]. Increased high climatic events may be due to the warming trends experienced globally [3]. Climate change impacts ecosystems and coastal communities [4, 5]. Hurricanes lead to significant damage to the infrastructure due to the strong winds. The ten most destructive tropical cyclones in U.S. history occurred in the past thirty years [6]. The increased hurricane activity could be related to climate change [7, 8]. Increased hurricane activity brings significant damage to the infrastructure. Post-disaster investigations have reported substantial damage and failures of road signs, large-size billboards, and overhead sign structures due to windstorms. Damage to billboards can be local at the connecting bolts between the cladding plate and the supporting structure, damage to the plate skin due to intense local end pressures on the plate, damage to the supporting frame, local buckling of the supporting column, or failure of its foundation bolt connection [9]. Failures in most road signs and billboards do not pose an imminent danger to human life, whereas overhead sign structures do. Various combinations of panels and supports can form an overhead sign structure. The sign panels consist of either standard aluminum flat signs that vary in height to base ratios or variable message signs (VMS) that have a thickness to them and display a digital message. Sign supports vary from monotube cantilever poles that span across two lanes to a bridge truss that can span across several lanes of traffic. A cantilevered sign support consists of a single vertical column and a horizontal beam commonly referred to as the mast arm, that displays and supports sign panels. For most roadways, cantilevered support structures are a good option and are the mostpopular type of overhead sign structure throughout the United States for several reasons. One reason is that the cost of a cantilevered support structure is less than 40 percent of the cost of a larger overpass supports. Another reason is that it has only one singular vertical upright, increasing motorist safety by reducing the probability of collision [10]. However, as roadways continue to add more lanes, the horizontal beam of the support structure continues to extend further over traffic, testing the limits of the cantilevered sign structure. Another issue due to the extension of the horizontal beam is the increased setback distance of the upright from the roadway (for safety reasons). This increase in length results in a higher moment at the critical connections, increased flexibility, and wind-induced oscillations that cause severe fatigue, making cantilever structures vulnerable to vibrations and fatigue cracking by wind forces [11]. Highway sign structures are susceptible to wind-induced fatigue loads induced by flutter, buffeting, vortex-shedding, and vibrations [12]. During the past decades, these structures have shown problems associated with fatigue performance. The problems amplify by defective welds, aging material, and harsh environmental conditions [13]. There have been numerous studies to reduce fatigue loads under normal wind conditions; however, there is less research on minimizing the amount of force on the panel. The literature contains extensive research on bluff body aerodynamics, but few studies have explored the effects of wind loads acting on sign panels on overhead sign supports. A fundamental aspect of analyzing sign panels subject to wind loads is understanding the flow interaction with the structure and its impact on the induced forces and pressures. Accurate prediction of these wind forces and characteristics is critical to minimizing wind loads on the sign panels.