摘要: |
The use of Intelligent Transportation Systems (ITS) technologies on highways is an attractive option for traffic facility operators. Variable Message Signs (VMS) are the cornerstone of ITS infrastructure as they relay messages to motorists for warnings of hazards ahead such as fog, traffic congestion, accidents, construction, and lane closings. VMS messages are of paramount importance in ensuring safety and avoiding fatal crashes (such as the multi-vehicle accident and fatalities along I-75 of Gainesville, Florida, in January 2012 when drivers were blinded by a combination of fog and smoke caused by a nearby brushfire). The objective of this project is to develop accurate drag coefficients for incorporation in the American Association of State Highway and Transportation Officials (AASHTO) Supports Specifications to foster safer and more economic design of VMS structures. The research will: (1) perform full-scale wind (and rain) testing of VMS structures (or portions thereof) at the 12-fan Wall of Wind facility (WoW) of Florida International University (FIU) and measure drag, gust effects, system responses, and failure modes (if any) under a range of service level and extreme wind conditions; (2) compare WoW data to available field measurements for fatigue wind velocities; (3) develop drag coefficients for both fatigue and extreme wind (and rain) conditions; (4) determine fatigue behavior and extreme event failure of connections, members, and foundations subjected to WoW test-based data using dynamic finite element modeling at the University of Alabama, Birmingham (UAB); (5) quantify possible economic benefits gained when using separate drag coefficients for fatigue and ultimate strength design and assess the impact of new coefficients on the design of structural supports; and (6) develop new specifications for AASHTO by stipulating separate drag coefficients to use with fatigue and extreme wind loading for design of VMS structures. |