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Fatigue Behavior of the Reinforced Electrical Access Hole in Aluminum Light Support Structures

Schlatter, Clark Robert
http://rave.ohiolink.edu/etdc/view?acc_num=akron1490359262398947

Abstract Details

2017, Master of Science in Engineering, University of Akron, Civil Engineering.
Aluminum light poles are constructed from extruded aluminum tube in order to minimize the use of material. This in turn makes the pole lighter and allows for the electrical wires for the light to be hidden inside the pole. These wires must still be accessed for installation and maintenance purposes. An electrical access hole with a cover is placed near the bottom of the pole to make the wires accessible. This electrical access hole is a point of structural weakness in the pole; therefore, the electrical access hole is often reinforced. This reinforcing may solve potential static load problems, but the disruption in the load path is a potential fatigue crack initiation point. This research centered on how fatigue failure occurs in cast reinforced electrical access holes. The majority of the experimental research consisted of the cyclical bending of tubes with the electrical access holes centered in the extreme tension fiber. Ten poles with electrical access holes were broken in fatigue. The stress range applied to these varied from 63 MPa (9.1 ksi) at the highest to 17 MPa (2.5 ksi) at the lowest. Three tensile tests and a high shear fatigue test were conducted to supplement would could not be observed from the cyclical bending tests. Finite element models were developed to understand the mechanical response of the electrical access hole. These were similar to the bending and tensile samples. A finite element model in a cantilevered position was modeled as well. These models allowed for stress maps to be examined and a potential explanation for initial cracking to be developed. The initial cracking of the electrical access hole occurs in the weld near the minor axis of the elliptical hole. This initial cracking was due to distortion of the reinforcing of the electrical access hole. These cracks either propagate through the reinforcing or join together to cause final failure. The stress range versus the cycles to failure for the electrical access hole was plotted to compare the data to known aluminum fatigue details. The data all fell between categories C and D for aluminum. Further research is needed to verify if a D detail can be used for designing the electrical access hole in fatigue.
Craig Menzemer, Ph.D. (Advisor)
Anil Patnaik, Ph.D. (Committee Member)
Wieslaw Binienda, Ph.D. (Committee Member)
66 p.
Civil Engineering

Recommended Citations

Citations

  • Schlatter, C. R. (2017). Fatigue Behavior of the Reinforced Electrical Access Hole in Aluminum Light Support Structures [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1490359262398947

    APA Style (7th edition)

  • Schlatter, Clark. Fatigue Behavior of the Reinforced Electrical Access Hole in Aluminum Light Support Structures . 2017. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1490359262398947.

    MLA Style (8th edition)

  • Schlatter, Clark. "Fatigue Behavior of the Reinforced Electrical Access Hole in Aluminum Light Support Structures ." Master's thesis, University of Akron, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1490359262398947

    Chicago Manual of Style (17th edition)

akron1490359262398947
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This open access ETD is published by University of Akron and OhioLINK.