Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xii, 160 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 104-106).

Existing reinforced concrete (RC) structure can be strengthened upon the addition of externally bonded high-strength light-weight fibre-reinforced polymer (FRP) composites. An abundance of research over the last two decades has established the effectiveness of the externally bonded FRP via extensive experimental testing. Perhaps the most commonly occurring failure mode though is premature debonding of the FRP and debonding generally occurs at strains well below the strain capacity of the FRP. Debonding failures are undesirable as they are typically brittle and represent an under-utilisation of the FRP material. A straightforward means to prevent or at least delay debonding is by the addition of mechanical anchors, however, research to date on anchors is extremely limited. Of the various anchor concepts examined to date by researchers, this dissertation will focus on anchors made from FRP which are herein referred to as FRP anchors. The details and results of a program of research on the performance of FRP anchors in FRP-strengthened structures are presented in this dissertation. An extensive review of exiting literature helps establish knowledge gaps which serve to justify the need and the scope of the research reported herein. A novel bow-tie FRP anchor concept is then proposed and tested in smaller-scale single-shear FRP-to-concrete joint assemblages as well as larger-scale simply-supported FRP-strengthened RC slabs. The anchors are shown to increase the strength and slip capacity of the joints by up to 41 % and almost 600 %, respectively, in comparison with unanchored control joints. The anchors are then shown to increase the load and deflection capacity of slabs by 30 % and 110 %, respectively, above an unanchored control slab. In addition to strength, it is the ability of FRP anchors to introduce deformability into FRP-strengthened RC slabs which is particularly beneficial in order to produce safer structures. An analytical model is then developed which is based on a novel quad-linear moment-curvature response which can capture the complete load-deflection response of the FRP-strengthened slabs anchored with FRP anchors. The analytical modeling approach enables closed-form equations to be derived which can then be used by design engineers to relatively easily construct load-deflections responses and accurately predict member responses. Following the concluding comments for the project as a whole, future research topics of relevance are identified. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

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ACI Committee 544's repeated drop-weight impact test for concrete is often criticized for large variations within the results. This paper identifies the sources of these large variations and accordingly suggests modifications to the ACI test. The proposed modifications were evaluated and compared to the current ACI test by conducting impact resistance tests on 40 specimens from two batches of polypropylene fiber-reinforced concrete (PPFRC). The results obtained from both methods were statistically analyzed and compared. The variations in the results were investigated within the same batch and between different batches of concrete. The impact resistance of PPFRC specimens tested with the current ACI test exhibited large coefficients of variation (COV) of 58.6% and 50.2% for the first-crack and the ultimate impact resistance, respectively. The corresponding COV for PPFRC specimens tested according to the modified technique were 39.4% and 35.2%, indicating that the reliability of the results was significantly improved. It has been shown that, using the current ACI test, the minimum number of replications needed per each concrete mixture to obtain an error below 10% was 41 compared to 20 specimens for the modified test. Although such a large number of specimens is not good enough for practical and economical reasons, the reduction presents a good step on the development of a standard impact test.

Dissertation (PhD)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 288-293). Also available in electronic version.