This thesis explores the quality of hand-manufactured carbon-epoxy IsoTruss® grid structures for use as reinforcement in concrete piles. Large IsoTruss® grid structures were manufactured and embedded in 14.0" (35.6 cm) diameter concrete to create IsoPiles™. The IsoPiles™ were designed to have flexural characteristics similar to steel reinforced concrete piles of equal diameter. Bending stiffness was matched based on the longitudinal members. A method for comparing transverse steel reinforcement to helical IsoTruss® members was developed, along with equations to facilitate the design of IsoTruss® structures with rounded nodes.
Compression tests were performed on 3.0 ft (0.91 m) long sections taken from the ends of each of the two 30 ft (9.14 m) long IsoTruss® grid structures manufactured. Fiber volume fraction, void fraction, and cross section area inspections were performed on IsoTruss® samples to determine quality. The strength, stiffness, and fiber volume fraction data obtained from these tests are compared to values obtained previously  for the same consolidation method. The quality of hand-manufactured large IsoTruss® grid structures was quantified by performing microscopic inspection of the members, by testing the reinforcement cage in compression, and by testing short section of IsoTruss® and steel reinforced concrete piles in compression. Compression tests were performed on short sections taken from the ends of the IsoPile™ specimens. These were compared with compression tests performed on equivalent steel-reinforced piles to evaluate the viability of the IsoTruss® as reinforcement in concrete piles.
Insufficient tension on the fiber during manufacturing and insufficient radial compression during the cure resulted in an average fiber volume fraction 13% lower than previously obtained, causing the ultimate compressive strength and Young's modulus of the IsoTruss® reinforcement cages to be 51% and 22% lower, respectively, than previous data. The IsoTruss®–reinforced piles had an ultimate compressive load that was within 4% of the ultimate compressive load of the steel-reinforced piles.
College and Department
Ira A. Fulton College of Engineering and Technology; Civil and Environmental Engineering
BYU ScholarsArchive Citation
McCune, David Thomas, "Manufacturing Quality of Carbon/Epoxy IsoTruss (R) Reinforced Concrete Structures" (2005). Theses and Dissertations. 278.
IsoTruss, composites, reinforced concrete, piles