scope:

Foreword

The sixth edition of Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals supersedes the fifth edition and its 2010 and 2011 interims. It includes changes approved by the Highways Subcommittee on Bridges and Structures in 2012.

Design guidelines for fatigue-critical multisided tubular sections are included in Section 5, "Steel Design." Additional guidance is provided on longitudinal seam welds, tube-to-transverse plate connection welds, anchor bolt installation, and stiffened connections. New figures for fillet-welded gusseted box connections and ring-stiffened box connections are provided as commentary. Section 5 also includes updates to hand-hole welds, weld inspection, and provides new figures for holes and cutouts.

The scope of Section 11, "Fatigue Design," is expanded to allow design of support structures using nominal stressbased classifications of typical connection details, or using the alternate local stress-based and/or experiment-based methodologies presented in Appendix D. New tables are provided for determining the fatigue resistance of typical connection details in support structures for finite and infinite life designs. The scope of Section 11 is expanded to include separate provisions for high-mast lighting towers, including a combined wind load for a simplified approach to derive fatigue damage from all the load effects due to natural wind.

The Specifications are based on the allowable stress design methodology and are intended to address the usual structural supports. Requirements more stringent than those in the Specifications may be appropriate for atypical structural supports. The commentary is intended to provide background on some of the considerations contained in the Specifications; however it does not provide a complete historical background, nor detailed discussions of the associated research studies. The Specifications and accompanying commentary do not replace sound engineering knowledge and judgment.

AASHTO Highways Subcommittee on Bridges and Structures