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Pages 6-12

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From page 6...
... 6 Introduction and Research Approach 1.1 Problem Description and Problem Statement With increased traffic, multilane highways, and complex highway interchanges, highway signs play an ever more important role in the safe operation of the nation's transportation network. A detailed understanding of stresses during the service life of sign support structures is crucial for their safe and economic design.
From page 7...
... Introduction and Research Approach 7 together for longer spans. Circular cross-section and L-shaped members most commonly are utilized for trusses supporting highway signs.
From page 8...
... 8 Wind Drag Coefficients for Highway Signs and Support Structures be too conservative, specifying drag coefficient values as much as 50% higher than those in the LRFDLTS-1 specifications. Given the wide range of recommended values for drag coefficients in different standards and research studies -- and given the high probability that the LRFDLTS-1 recommendations are not sufficiently conservative -- the recommendations for simple static rectangular signs installed above the ground need to be updated.
From page 9...
... Introduction and Research Approach 9 or an L-shaped cross-section. The current LRFDLTS-1 specifications provide drag coefficients only for two members (one in front of the other)
From page 10...
... 10 Wind Drag Coefficients for Highway Signs and Support Structures (Constantinescu, Bhatti, and Phares 2018)
From page 11...
... Introduction and Research Approach 11 on the highway signs and on the members and elements of the sign support structure are then integrated to calculate the wind load forces and estimate the mean drag coefficients. 1.5 Research Tasks Nine research tasks were completed to address the research objectives discussed in Section 1.3 and to develop recommendations for revision of the AASHTO LRFDLTS-1 specifications.
From page 12...
... 12 Wind Drag Coefficients for Highway Signs and Support Structures of providing additional validation data for isolated rectangular signs, side-by-side rectangular signs, and signs that include an add-on sign. Per the task structure specified in the RFP for this NCHRP project, the research team developed a three-phase research approach to complete the project: • Planning: Conduct a literature review to identify knowledge gaps in the calculation of wind drag coefficients and wind loads for highway signs and sign support structures.

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