10-29-2012, 03:22 AM
STUDIES ON BOND AND CRACKING OF STRUCTURAL CONCRETE
by Homayoun H. Abrishami, June 1994
Department of Civil Engineering and Applied Mechanics
McGill University, Montreal, Canada
A thesis submitted to
the Faculty of Graduate Studies and Research
in partial fulfilment of the requirements for the degree of
Doctor of Philosophy
ABSTRACT
This thesis presents new testing methods to study the bond characteristics of reinforcing
bars and pretensioned strands. For reinforcing bars, the new technique, which simulates a more uniforrn bond stress, enabled the study of both pullout failures and splitting faiiures. Variables studied included concrete cover, bar size and the erfect of epoxy coatings on the bars. Analytical expressions for predicting the bond stress versus slip response and the bond stress distribution for different types of pullout tests are developed. For pretensioned strand, the testing technique enabled the study of the bond characteristics along toth the transfer and the flexural bond lengths. Equations for predicting the trasnfer development lengths are given.
The tensile behaviour of concrete members reinforced with a single reinforcing bar are studied. Variables studied included concrete strength, presence of steel fibres, bar size and the effect of epoxy coatings on the bars. Both transverse cracks and splitting cracks were studied and a factor accounting for the influence of splitting cracks on tension stiffening is introduced. A procedure for predicting the response of tension members, accounting for the concrete coyer and bar size and the presence of steel fibres is given. Equations are suggested to deterrnine the transfer length and crack spacing.
Experimental investigations were carried out to study the post-cracking behaviour of bearns
without stirrups. The influence of concrete strength and the presence of epoxy-coated reinforcement on the crack development, type of cracking, ductility and failure mechanism are discussed. Typical slab-colurnn connections found in parking structures were tested, simulating the construction stages. The effects on crack development of both concrete quality and the presence of epoxy coatings on the reinforcement were studied. Modification factors for predicting crack widths in bearns and two-way slabs, accounting for the presence of epoxy coatings, are given in a forrn suitable for implementation in codes of practice.
by Homayoun H. Abrishami, June 1994
Department of Civil Engineering and Applied Mechanics
McGill University, Montreal, Canada
A thesis submitted to
the Faculty of Graduate Studies and Research
in partial fulfilment of the requirements for the degree of
Doctor of Philosophy
ABSTRACT
This thesis presents new testing methods to study the bond characteristics of reinforcing
bars and pretensioned strands. For reinforcing bars, the new technique, which simulates a more uniforrn bond stress, enabled the study of both pullout failures and splitting faiiures. Variables studied included concrete cover, bar size and the erfect of epoxy coatings on the bars. Analytical expressions for predicting the bond stress versus slip response and the bond stress distribution for different types of pullout tests are developed. For pretensioned strand, the testing technique enabled the study of the bond characteristics along toth the transfer and the flexural bond lengths. Equations for predicting the trasnfer development lengths are given.
The tensile behaviour of concrete members reinforced with a single reinforcing bar are studied. Variables studied included concrete strength, presence of steel fibres, bar size and the effect of epoxy coatings on the bars. Both transverse cracks and splitting cracks were studied and a factor accounting for the influence of splitting cracks on tension stiffening is introduced. A procedure for predicting the response of tension members, accounting for the concrete coyer and bar size and the presence of steel fibres is given. Equations are suggested to deterrnine the transfer length and crack spacing.
Experimental investigations were carried out to study the post-cracking behaviour of bearns
without stirrups. The influence of concrete strength and the presence of epoxy-coated reinforcement on the crack development, type of cracking, ductility and failure mechanism are discussed. Typical slab-colurnn connections found in parking structures were tested, simulating the construction stages. The effects on crack development of both concrete quality and the presence of epoxy coatings on the reinforcement were studied. Modification factors for predicting crack widths in bearns and two-way slabs, accounting for the presence of epoxy coatings, are given in a forrn suitable for implementation in codes of practice.
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