Operational Post Deformation of Cantilever Sign Support Structures from Truck-Induced Wind Gusts
Publication: Practice Periodical on Structural Design and Construction
Volume 23, Issue 1
Abstract
The application of operational modal analysis using frequency domain decomposition revealed the operational behavior of a cantilever sign support structure in response to truck-induced wind gusts. The study identified the modes of vibration that contribute to the total deformation of the structure during service. The research involved experimentation of an on-site cantilever sign support structure under a controlled test regime of truck gusts. The study measured normal- and shear-strain deformations around the circumference of the post in proximity to the base-plate weld. The results indicated a multiple-degrees-of-freedom dynamic system with two equally contributing modes of vibration. The modes resembled torsional and flexural vibrations about the post. The resulting operational deflected shape had a distinctive beating vibration response due to the modal contributions. The truck fatigue loading provisions of the AASHTO supports specifications were overly conservative for the tested structure and truck type.
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Acknowledgments
The work described in this document culminated from research sponsored by the Alabama DOT (ALDOT) Project 930-683 entitled “Design of Overhead Sign Structures for Fatigue Loads.” It is important to acknowledge the hard work and dedication of the ALDOT Maintenance Bureau for successful completion of the project.
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Information & Authors
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Published In
Practice Periodical on Structural Design and Construction
Volume 23 • Issue 1 • February 2018
Copyright
© 2017 American Society of Civil Engineers.
History
Received: May 3, 2017
Accepted: Aug 23, 2017
Published online: Dec 13, 2017
Published in print: Feb 1, 2018
Discussion open until: May 13, 2018
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