Minimum Design Loads for Buildings and Other Structures provides requirements for general structural design and includes means for determining dead, live, soil, flood, wind, snow, rain, atmospheric ice, and earthquake loads, as well as their combinations, which are suitable for inclusion in building codes and other documents. This Standard, a revision of ASCE/SEI 7-05, offers a complete update and reorganization of the wind load provisions, expanding them from one chapter into six. The Standard contains new ultimate event wind maps with corresponding reductions in load factors, so that the loads are not affected, and updates the seismic loads with new risk-targeted seismic maps. The snow, live, and atmospheric icing provisions are updated as well. In addition, the Standard includes a detailed Commentary with explanatory and supplementary information designed to assist building code committees and regulatory authorities. Standard ASCE/SEI 7 is an integral part of building codes in the United States. Many of the load provisions are substantially adopted by reference in the International Building Code and the NFPA 5000 Building Construction and Safety Code. Structural engineers, architects, and those engaged in preparing and administering local building codes will find this Standard an essential reference in their practice. Note: New orders are fulfilled from the second printing, which incorporates the errata to the first printing.

Minimum Design Loads for Buildings and Other Structures

Investigation of fatigue in steel sign-support structures under diurnal temperature changes

Reliability consideration for fatigue design of sign, luminaire, and traffic signal support structures under wind load

Changes in the AASHTO fatigue design equations for truck-induced gust loads have been made in recent years. However, there has not been any long-term field testing of cantilevered traffic signal structures to verify the design equations. In this study, two cantilevered traffic signal structures were monitored in field testing to determine the effects of truck-induced gust loads. Over 400 truck events were observed in the field, but only eighteen trucks produced a detectable effect on the cantilevered traffic signal structure. Interestingly, the truck-induced gusts caused a greater effect in the out-of-plane direction (same direction as traffic flow) instead of the in-plane direction that is included in the AASHTO Specifications. It was determined that overall natural wind gusts produce a larger response in cantilevered traffic signal structures than gusts produced by trucks passing beneath the signals.

Field Testing of Cantilevered Traffic Signal Structures underTruck-Induced Gust Loads

Drag or normal force coefficients on a range of rectangular signboards or hoardings with varying aspect ratios, clearance ratios and porosity's are presented for a range of wind directions and compared with various design data. Whereas, there is reasonably good agreement for data for walls on ground, significant discrepancies exist in normal force coefficients for cases as the pane! becomes elevated in the boundary layer. Discrepancies in codification have been highlighted and revised loading data recommended.

Wind loads on rectangular signboards and hoardings

A unified design method for fatigue loading caused by natural wind for highway overhead sign support structures is needed. Whereas the fatigue design provisions given in the 2001 AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals provide fatigue design criteria for natural wind, these provisions are applicable only within certain limitations. A comprehensive approach was developed for fatigue design for the treatment of sign support structures, considering the dynamic properties of the structures such as the natural frequency and damping characteristics. The approach is applicable for structures in which the dynamic response can be approximated by a single degree-of-freedom system. Typical examples include cantilever- and bridge-type overhead sign support structures. The proposed fatigue design approach incorporates these parameters in a simplified, systematic procedure that can be readily used by the engineer. The analytical work performed involved pr...

Fatigue Design of Sign Support Structures for Loading Caused by Natural Wind Loads

A cantilevered sign support structure failed, which was attributed to fatigue fracture of the anchor bolts. The failed structure was designed before the publication of the AASHTO fatigue provisions. The structure was replaced with a similar arrangement but designed using the AASHTO fatigue provisions. It was equipped with a double-nut-moment joint to concrete foundation using a 31.75-mm (1.25-in.) thick, 889-mm (35-in.) diameter base plate and eight galvanized 38.1-mm (1.5-in.) diameter bent anchor bolts. Significant clearance discrepancies between the base plate and the foundation for each of the anchor bolts existed because of topographical limitations. Experimental evaluation on the fatigue behavior attributable to natural wind was conducted on the anchor bolt attachments for validation of the AASHTO fatigue provisions. The results of the study indicated an irregular distribution of stress ranges between anchor bolts, with a portion having stress ranges greater than the values calculated using ...

Experimental Validation of the AASHTO Natural Wind Fatigue Design Specifications for Cantilevered Sign Support Structure Anchor Bolts

This research presents a universal approach for determining the design fatigue load due to truck-induced wind gust for highway overhead sign support structures. The fatigue load is determined on the basis of the dynamic properties of the structure. It is applicable to structures in which the dynamic response can be approximated by a single-degree-of-freedom system. Typical examples include cantilever- and bridge-type overhead sign support structures. The developed approach incorporates these parameters in a simplified systematic procedure that can be readily used by engineers. Principles relating to mechanical vibration and utilization of the shock response spectrum were used to determine the load. The fatigue load is selected from the shock response spectrum in terms of the natural frequency of the structure and the speed of the truck. Comparisons were made with the current truck-induced gust fatigue design provisions given in the 2009 AASHTO Standard Specifications for Structural Supports for Highway Si...

Design Fatigue Load of Sign Support Structures Due to Truck-Induced Wind Gust

The 2001 edition of the American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals has been revised in its entirety through a major research project conducted under the auspices of the National Cooperative Highway Research Program (NCHRP 17-10). A major part of the revision includes updated provisions and criteria for extreme wind loads and new provisions and criteria on fatigue design. These provisions differ considerably from those in previous editions of the specifications. The impact of the fatigue criteria on the design of highway overhead variable message sign (VMS) support structures has not been evaluated and is not currently being implemented by the Alabama Department of Transportation (ALDOT). The main goal of the proposed work was to conduct an experimental program to develop realistic loading criteria for the use in fatigue design of bridge-type overhead VMS support structures. The study addressed fatigue loading related to natural wind and truck-induced wind gusts. An efficient step-by-step design methodology was formulated and made available from the established fatigue loading. The data analyses involved fundamental principles related to Structural Dynamics. Design examples with associated commentary are provided that describe the methodology and application of the fatigue loading criteria developed from this study. Recommendations for fatigue design of overhead VMS support structures were made.

https://rosap.ntl.bts.gov/view/dot/25439/dot_25439_DS1.pdf

Ian E. Hosch

Papers

Fatigue Design of Sign Support Structures for Loading Caused by Natural Wind Loads

Experimental Validation of the AASHTO Natural Wind Fatigue Design Specifications for Cantilevered Sign Support Structure Anchor Bolts

Design Fatigue Load of Sign Support Structures Due to Truck-Induced Wind Gust

Design of Overhead VMS Structures for Fatigue Loads

Full-Scale Wall of Wind Testing of Variable Message Signs (VMS) to Develop Drag Coefficients for AASHTO Supports Specifications