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Evaluation Of Concrete Barrier As Rockfall Protection

Musa, Abdisa
http://rave.ohiolink.edu/etdc/view?acc_num=akron1430503509

Abstract Details

2015, Doctor of Philosophy, University of Akron, Civil Engineering.
Rockfall is the movement of rocks down a slope which may be in the form of freefall, bouncing, rolling and sliding based on characteristics of slopes and nature of rocks. When rockfalls reach the roadway, they are hazardous to roadway users. Modified traffic concrete barriers that are standardized via crash test from the roadside as per National Cooperative Highway Research Program (NCHRP) Report 350 Test Level 3 (TL-3) criteria are commonly used by Ohio Department of Transportation (ODOT) to protect highways from rockfall hazards. The two most commonly used concrete barriers by ODOT are 32 inch high precast concrete barriers (PCB) and 42 inch high modified cast in place concrete barriers (CIP). The impact energy absorption limits and containment effectiveness of these barriers are relatively unknown and there is little knowledge of the efficiency of these barriers against rockfall. The objectives of this dissertation is to define the impact energy absorption limit and efficiency of these barriers against rockfall as well as the development of the new designs of concrete barriers for future applications. Two phases of impact tests were conducted in the field with Test Rocks of reinforced concrete, steel balls and natural stone. Phase 1 impact testing was designed for a maximum impact energy of 70 kJ on test barriers. Phase 2 impact testing was designed based on results from Phase 1 for the new designs of concrete barriers (PCB and CIP) with an impact energy of more than 180 kJ. The revised designs for new concrete barriers include the use of smaller size reinforcing bars and spacing, steel/polypropylene fibers, use of welded wire fabrics (WWF) and black reinforcing bars without epoxy coating. The results from Phase 1 impact testing indicated that current ODOT standard PCBs has a limit of an energy absorption capacity of 24 kJ under single impact and the capacity is much lower under multiple impacts. The modified traffic CIP concrete barriers has the maximum energy absorption capacity of 56 kJ under single impacts. During Phase 2 impact testing, the revised designs of PCBs with addition of fibers has the impact energy absorption limit of 45 kJ and reduced cracks patterns were observed. The maximum energy absorptions of the CIP concrete barriers with revised designs were observed to be as high as 156 kJ. The used of fibers increased the energy absorption capacities and also reduced the crack patterns in the concrete barriers. The use of steel fibers in the wet concrete increased the energy absorption capacity by around 40% and the polypropylene fibers increased the energy absorption capacity by 20%. The epoxy coating on the surface of the reinforcing bars reduced the bond to the surrounding concrete and increased the spalling of the concrete. The finite element modeling for the displacements and the strains were validated with high speed video of field data analyzed by ARAMIS.
Anil Patnaik, Dr. (Advisor)
Robert Liang, Dr. (Committee Member)
Craig Menzemer, Dr. (Committee Member)
Xiasheng Gao, Dr. (Committee Member)
Desale Habtzghi, Dr. (Committee Member)
196 p.
Civil Engineering
Rockfall, Concrete Barrier, Impact, Energy

Recommended Citations

Citations

  • Musa, A. (2015). Evaluation Of Concrete Barrier As Rockfall Protection [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430503509

    APA Style (7th edition)

  • Musa, Abdisa. Evaluation Of Concrete Barrier As Rockfall Protection. 2015. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1430503509.

    MLA Style (8th edition)

  • Musa, Abdisa. "Evaluation Of Concrete Barrier As Rockfall Protection." Doctoral dissertation, University of Akron, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430503509

    Chicago Manual of Style (17th edition)

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