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Typescript (photocopy). / Digitized by Kansas Correctional Industries

A dissertation submitted to the Faculty of Engineering, University of the Wttwatersrand, Johannesburg, in fulfilment of th e degree of Master of science in Engineering Johannesburg 1988 / This dissertation addresses the question of the fracture behaviour of notched concrete and mortar beams. The major purpose of the work was to study the development of the micro-cracked zone and identify the point at which main crack growth began, and thus to characterise concrete and mortar at the start of main crack growth. Notched concrete and mortur beams of width 100 mm, depth either 200 mm or 300 nun, and with a span/depth ratio of three, were tested. Measurements of midspan deflection, midspan load, surface displacements across the fracturing section and ultrasonic pulse transit time were made. Ordinary Portland cement and mineral aggregates were used for the concrete and mortar beams. The J'■integral, surface displacements across the fracturing section and ultrasonic pulse transit time measurements were used to detect the onset of main crack growth. It was found that a reduction in the load carrying capacity of concrete and mortar is possible due to micro-cracking only. The value of the J-integral at the start of main crack growth was found to be essentially the same for concrete and mortar. The value of the J-integral at the start of micro-cracking was ■ < found to be essentially the same for concrete and mortar, and about 40% of the value of the J-integral at the start of main crack growth. The value of the J-integral at the start of micro-cracking and at the start of main crack growth was found, on average, to increase for an increase in beam depth. Surface displacements across the fracturing section showed the tension zone at the start of main crack growth to be approximately twice the size of the compression zone for both concrete and mortar. The'size of the micro-cracked zone, as determined from surface displacements across the fracturing section, was found to be 42% of the residual ligament depth for concrete, and 41% of the residual ligament depth for mortar. Scatter in the results was found to be considerable, thus meaning that only general trends could be identified

Thesis. 1977. M.Arch.A.S.--Massachusetts Institute of Technology. Dept. of Architecture. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography : p. 177. / M.Arch.A.S.

Thesis (M.E.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 397-401). Available also in a digital version from Dissertation Abstracts.

Thesis--Ph. D., University of Hong Kong. / Offset from typescript.

Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains viii, 139 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 123-139).

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--University of Washington, 1989. / Vita. Includes bibliographical references (leaves [187]-191).