Document Type

Thesis - Open Access

Award Date

1982

Degree Name

Master of Science (MS)

Department / School

Civil Engineering

First Advisor

M. Nadim Hassoun

Abstract

The high tensile stresses in concrete have to be accommodated in most structural applications. Steel reinforcements are embedded in concrete, while casting, to produce a composite material known as reinforced concrete. Thus, reinforcing of concrete is an excellent solution to overcoming the weakness in tension and to reduce the volume of concrete, but it has two main disadvantages. Firstly, the cost of fabrication and placement of reinforcing bars and prestressing tendons is a substantial fraction of the total cost of construction. To counteract this expense, materials like steel fibers are used so that partial fabrication and detailing needs are reduced, due to the increase in tensile strength of fibrous concrete. Secondly, longitudinal bars must be spaced apart for concrete consolidation. This will leave a large space without reinforcement. Short discrete steel fibers spaced close together will increase the tensile strength of the matrix and also act as crack arrestors in tandem with the longitudinal bars. When the reinforcements are in the form of short discrete fibers, they act effectively as rigid inclusions in the concrete matrix. Physically, they have thus the same order of magnitude as aggregate inclusions. Steel fibers reinforcement, therefore, cannot be regarded as direct replacement of longitudinal reinforcement in reinforced and prestressed structural members. It is well established that the addition of steel fibers greatly increases the ductility, the energy absorption capacity, and the ultimate strain capacity of concrete. Fiber reinforcement considerably improves the ultimate flexural strength, the post crack load-carrying capacity, impact resistance, shear, tensile, and fatigue strengths, shock resistance, and failure toughness. Fiber reinforced concrete has been found to be more economical than conventional concrete, for use at airports and overlays. It is gaining acceptance in use for thin section concrete applications such as sewer pipes, bridge overlays, and curtain walls. Fibrous concrete has been successfully used to minimize cavitation and erosion damage in structures where high velocity flows are encountered, such as sluices, spillways, navigation locks, and bridge piers. High strength concrete, with compressive strength higher than 6,000 psi, is now being widely used. There is one major drawback in the use of high strength concrete, its brittleness. In this case any failure is sudden and catastrophic. This is particularily true in structures that are subject to earthquakes, blasts, or suddenly applied loads. An ideal solution to overcome this serious disadvantage is to add steel fibers into the concrete. Recently there has been vast use of fibrous concrete in multistory buildings, bridges, and runways; although there is very little information available on the effects of steel fibers in beams reinforced with continuous bars. Therefore, this investigation was undertaken to determine the performance and characteristics of beams made with steel fiber concrete containing continuous reinforcing bars.

Library of Congress Subject Headings

Fiber-reinforced concrete
Concrete beams

Format

application/pdf

Number of Pages

310

Publisher

South Dakota State University

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