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Drag Coefficients For Highway Variable Message Sign Structures, Joseph Phillips
Drag Coefficients For Highway Variable Message Sign Structures, Joseph Phillips
All ETDs from UAB
Variable Message Signs (VMS) are becoming an integral part of transportation infrastructure on US interstates and highways. VMS structures are vital in ensuring the safety of motorists by relaying messages concerning potential road hazards such as fog, traffic congestion, highway construction, and lane closures. These structures are larger and heavier than typical flat panel signs, and thus behave differently when subjected to wind loads. The design of VMS structures is specified in the 2013 edition of the American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals. The AASHTO …
Bridge Rail Design Procedure, Emad Badiee
Bridge Rail Design Procedure, Emad Badiee
All ETDs from UAB
The AASHTO Bridge Specifications recommend a yield line theory analysis to determine the structural capacity of concrete bridge railing based on static strength of concrete. However, this analysis technique has been shown to significantly underestimate the capacity of concrete bridge rails to withstand high speed truck impacts. Traditionally this shortcoming has been mitigated by artificial reductions in bridge rail design loads implemented into the design specifications. Fear of litigation associated with failure of a bridge rail to contain and redirect an errant vehicle has made continuing this policy unacceptable for most state highway agencies. On the other hand, existing barrier …
Mitigating Fatigue Of Cantilevered Overhead Sign Structures Due To Natural And Truck-Induced Wind Gusts, Mohamed S. Gallow
Mitigating Fatigue Of Cantilevered Overhead Sign Structures Due To Natural And Truck-Induced Wind Gusts, Mohamed S. Gallow
All ETDs from UAB
Cantilevered overhead sign structures (COSS) are widely used across highways in the U.S. Several cases of failures have been reported for such structures due to fatigue wind loads. The structure’s dynamic characteristics such as natural frequency and critical damping are responsible for its behavior to these loads. When the frequency of wind gusts load matches the fundamental frequency of the OSS, resonance occurs, which causes excessive vibrations. Consequently, fatigue stresses increase and may exceed the fatigue critical limit, resulting in failure. Vibrations and fatigue stresses amplitudes are dependent on the structure’s natural frequency. The objective of this study is investigating …