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This Symposium Publication presents 13 papers on the use of fiber reinforcement in structural applications and assembles the thoughts of some leading researchers in the field. Collectively, these writings are a snapshot of contemporary thinking in this field and provide a direction for future activity. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP182

Processed cellulose fibers provide high levels of elastic modulus, tensile strength, bond strength to concrete, and durability. Their fine diameter also yields a close fiber spacing at relatively low fiber volume fractions, ad allows them establish a strong presence in the interface zones between reinforcing bars and concrete. Specialty cellulose fibers have been recently developed for convenient dispersion research project investigated the effect of specialty cellulose fibers at volume fractions of about .1% on the strength and toughness of bond between deformed bars and concrete. The experimental results were indicative of the effectiveness of specialty cellulose fibers in enhancing bond strength and toughness. The positive impact of specialty cellulose fibers on bond strength was more pronounced as fiber volume fractions increased to the upper limit of .18% considered in this investigation.

Steel, polyolefin and carbon fiber reinforced concretes were combined with traditional transverse steel reinforcement in the form of steel spirals. The complete stress-strain relationship and the ductility of the concrete in compression in both the unconfined and confined states was evaluated. The compressive toughness was evaluated both according to the Japanese Standard JSCE-SF5 and according to a new method proposed in the present work. The experimental program consisted of testing concrete cylinders under compression at two different strength levels: Normal (48 Mpa) and high strength (70 Mpa), polyolefin and carbon fibers. These tests were then repeated with different volume percentages Vf (1.5, 2.0 and 3.0) of steel, polyolefin and carbon fibers. These tests were then repeated with different pitches (25 and 50 mm). It was found that by combining fibers and steel spirals it is possible: (1) to obtain a high level of fracture energy dissipation, which could previously be obtained only by using a high volume percentage of spiral steel: and (2) to improve the maximum strain of the concrete, corresponding to the first failure of the spiral steel.

It is known that Steel Fiber Reinforced Concrete (SFRC) has advantages over plain concrete. In particular, fiber reinforcement makes concrete tougher and more ductile. Although these attributes are appealing for earthquake resisting structures, design codes do not yet incorporate specifications relative to the use of SFRC for structural applications. Recent developments have indicated a good potential for SFRC in structural and seismic applications. In the first part of this paper, the beneficial effects of SFRC in the seismic design of columns are briefly reviewed. The paper then presents an overview of an ongoing research project on compression. The variables considered were the fiber content of 0%, .5% and 1.0% per volume, the amount of transverse reinforcement for confining the column core, and the confinement provided by the fibers in the cover. It is shown that SFRC improves significantly the post-peak behavior of columns for all hoop spacing and the same seismic design philosophy. Although SFRC in the cover delay its spalling confine concrete, but rather change the failure mode by limiting the progression of cracks and enhancing the aggregate interlock along failure planes.

A simple analytical model is presented to predict the ultimate punching shear strength of slab-column connections made with steel fiber concrete. The model is based on the physical behavior of the connection under load, and is therefore applicable to both lightweight and normal weight concrete as well as to concrete without fibers. The model assumes that punching is a form of shearing without concrete crushing, and occurs when the tensile splitting strength of the concrete is exceeded. The theory is applied to predict the ultimate punching shear strength of forty seven slab-column connections tested by the authors and other researchers over a period of several years and designed to fail in shear, involving a wide range of fiber show very good agreement between the predicted and experimental values. The uniqueness of the model is that it incorporates many physical characteristics of the slabs and their failure behavior.-