Browsing by Author "Emmett A. Sumner, Committee Member"

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Bond Characteristics and Qualifications of Adhesives for Marine Applications and Steel Pipe Repair
(2005-07-19) Smith, Glen Eugene; Dr. Sami Rizkalla, Committee Chair; Emmett A. Sumner, Committee Member; James M. Nau, Committee Member
Performance of adhesives significantly affects the overall behavior of structural elements, especially in the process of developing innovative designs using new materials. Adhesives that bond metals, plastics, FRP and other materials have been used in transportation, industrial and marine applications. Fundamental understanding of the bond behavior and load transfer mechanisms of different adhesives is essential prior to their use in civil infrastructure applications. This thesis presents the results of an extensive research program conducted to determine the engineering properties of different structural adhesives under normal and severe environmental conditions. The bond characteristics between composite-to-composite and composite-to-steel materials are investigated. The performances of two different structural adhesives are evaluated by testing 105 single-lap shear specimens. The research includes the effect of severe environmental conditions using the classical direct lap-shear tests. The factor considered is time-to-failure in which the specimens are submerged in de-ionized water with different pH values and subjected to different temperatures at different stresses. The program includes also examining the cleavage peel and short term creep properties. Adhesive behaviors, as well as the failure modes for each adhesive, are presented. The influence of preparation procedures of the substrate on the shear strength of the adhesives is also studied. Test results show a significant impact of the pH level and temperature on the shear strength and bond characteristics of the two structural adhesives considered in this investigation. Test results were used to determine the most appropriate adhesive for marine application and repair of steel pipeline.
Erection and Strength Aspects of the Roof Trusses for RDU Airport Terminal C Project
(2008-07-24) Zubillaga, Jose Antonio; David W. Johnston, Committee Chair; Emmett A. Sumner, Committee Member; Michael L. Leming, Committee Member
Flexural Performance of MMFX Reinforcing Rebars in Concrete Structures
(2003-12-18) Yotakhong, Purk; Sami H. Rizkalla, Committee Chair; Mervyn J. Kowalsky, Committee Member; Emmett A. Sumner, Committee Member
Use of Micro-composite Multi-structural Formable Steel, commercially known as "MMFX", as a replacement for convention steel is gaining popularity in many concrete structures. The high-corrosive resistance nature and high-strength characteristics of the MMFX rebars could provide additional service life to concrete structures in areas that are prone to severe environmental conditions. The research program presented in this thesis was designed to study the flexural behavior of rectangular concrete beams reinforced by MMFX rebars. This thesis presents the experimental program carried out at the Constructed Facility Laboratory (CFL), North Carolina State University, to test a total of four large-scale concrete beams. All beams were 16 feet long, 12 inches wide, and 18 inches high. Three beams were reinforced by MMFX rebars in the tension side, and one beam was reinforced by conventional steel rebars in the tension side. All beams were equally reinforced by conventional steel rebars on the compression side. Three beams were tested under static loading conditions, while the remaining MMFX reinforcing beam was tested under a slow cyclic loading condition. All beams were tested to failure in order to investigate the behavior during the pre-cracking, cracking, post-cracking, ultimate capacities, and modes of failure.