Date of Award

Fall 1999

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering - (M.S.)

Department

Civil and Environmental Engineering

First Advisor

Methi Wecharatana

Second Advisor

C.T. Thomas Hsu

Third Advisor

Dorairaja Raghu

Abstract

In present direct tension tests, the complete stress-deformation curves, the resulting energy dissipated by damage, and the fracture energy of different types of cementitious composites, namely plain concrete, high strength concrete, normal fibrous concrete, high strength fibrous concrete, are studied and a ductility factor is calculated. It has been found that with the increasing strength of concrete due to the addition of the pozzoians such as silica fume and fly ash and when changing from normal strength to high strength, concrete ductility decreases. However, when fibers are combined with these matrices, concrete ductility increases. It is because of ductile steel fibers and the brittle plain concrete matrix affects the post-peak response of unreinforced composite specimens loaded in tension after exceeding the peak tensile strength.

With some concerns about the decrease in ductility found in unreinforced high strength concrete specimens loaded in tension, the ductility of high performance reinforced concrete beams made from pozzolanic material was also experimentally investigated. The results shows that the "brittle or ductile" behavior of cementitious composite materials, which can be observed by the post-cracking response obtained from the uniaxial direct tension test at the material level, is compatible with the"brittle or ductile" behavior exhibited by the reinforced concrete beams under flexural loading.

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