Details:

Creators:
Frymoyer, Mark ; Berman, Jeffrey
Frymoyer, Mark ; Berman, Jeffrey Less -
Corporate Creators:
Transportation Northwest (Organization)
Subject/TRT Terms:
[+]
Forecasting Luminaires Roads--Lighting--Supports--Washington (State)--Aerodynamics Street Lighting Structural Members Structural Supports Welded Joints--Cracking--Washington (State)--Forecasting Welds
Publication/ Report Number:
TNW2010-01
Resource Type:
Tech Report
Geographical Coverage:
Washington
OCLC Number:
664685082
Edition:
Final research report.
Corporate Publisher:
Transportation Northwest (Organization)
NTL Classification:
NTL-HIGHWAY/ROAD TRANSPORTATION-Bridges and Structures;NTL-SAFETY AND SECURITY-Highway Safety;
Abstract:
Recent fatigue failures of in-service luminaire support structures in Washington and around the country have

prompted concern about their fatigue resistance. Most luminaire support structures in Washington were designed

without attention to fatigue or with vague and incomplete fatigue design provisions. Furthermore, most luminaire

support structures were installed during the construction of the Interstate system in the 1960s, and as many as half

are estimated to have exceeded their 25-year design life. This research was initiated to help the Washington State

Department of Transportation (WSDOT) prioritize the inspection and replacement of luminaire support structures

throughout the state and to develop rational inspection procedures.

The research had four primary components: a literature review, experimental fatigue testing of two in-service

luminaire poles, a finite element analysis of the pole base, and development of a framework for estimating

remaining life. The extensive literature review found previous experimental studies, which were used to identify

details in older WSDOT luminaire support structures that may be critical and to help inform the selection of test

specimens. Quasi-static and high cycle fatigue testing were performed on two previously in-service luminaire poles

to determine the stress concentration factors (SCF) in critical details and determine fatigue resistance. The results

were then compared to the finite element analysis and the fatigue classifications used in design. The finite element

model was also used to determine the impact of parameters including base plate thickness, hand hole stiffener

thickness, and location of anchor bolts. The individual components of a framework for estimating the remaining

life of luminaire support structures in Washington were developed on the basis of a procedure established by Foley

et al. (2004) in their study of the remaining life of sign bridge structures.

The remaining fatigue life of the critical details in the previously in-service luminaire support structures were

found to exceed their design life. Cracking at the stiffened hand hole detail was found to be the ultimate limit state

for both specimens but was observed at cycle counts that were well beyond the design life. High SCFs were

measured in both compression and tension at the CJP weld toe, indicating the importance of base plate flexibility,

anchor bolt layout, and a uniform bearing surface. While it was not possible to know the load history for the

selected specimens, it is clear that the number of damaging cycles was low and that the fatigue design life for these

details is conservative. Recommendations for luminaire inspection are provided.


Format:
PDF
Funding:
DTRT07-G-0010
Collection(s):
US Transportation Collection University Transportation Centers
Main Document Checksum:
[+]
urn:sha256:41ad995646eccafac2371462741becab673e44e2d828c8b3c552b719fd839f99
Download URL:
https://rosap.ntl.bts.gov/view/dot/17555/dot_17555_DS1.pdf
File Type:

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