A series of full-scale axial compression tests was conducted on RC and SFRC columns. The specimens, which were detailed with varying amounts of transverse reinforcement, were cast using a self-consolidating concrete (SCC) mix that contained various quantities of fibres. The results demonstrate that the addition of fibres leads to improvements in load carrying capacity and post-peak response. The results also show that the addition of steel fibres can partially substitute for the transverse reinforcement in RC columns, thereby improving constructability while achieving significant confinement. Analytical models for the prediction of the load-strain response of SFRC columns are presented and validated with the experimental results. The tensile behaviour of SFRC members reinforced with a single reinforcing bar was also studied. The results indicate that the addition of fibres leads to improvements in tension stiffening and crack control. A procedure for predicting the response of tension members, accounting for the presence of fibres, is presented. Experimental investigations were carried out on a series of RC and SFRC beams. The effects of steel fibres on shear capacity, failure mechanism and crack control are studied. The results show that the addition of steel fibres leads to improvements in load carrying capacity and can lead to a more ductile failure. A simple procedure that can be used to predict the ultimate shear capacity of SFRC beams is introduced and validated using results from other researchers. / Une série d'essais a été réalisée sur des poteaux de taille réelle soumis à des charges axiales. Les échantillons, qui avaient des quantités variables d'armature transversale, ont été construits en utilisant un béton auto-plaçant qui contenait une quantité variable de fibres métalliques. Les résultants de cette étude expérimentale démontrent que la présence des fibres influence positivement la capacité portante des poteaux. De plus, les résultats montrent que l'utilisation d'un béton renforcé de fibres métalliques (BFM) peut s'avérer une solution appropriée pour assurer une ductilité adéquate aux poteaux. L'auteur propose des modèles analytiques pour prédire le comportement de poteaux chargés uniaxialement. Le comportement sous tension d'éléments en BFM armés d'une seule barre a été étudié. Les résultats montrent que la présence de fibres améliore la résistance en tension. Une procédure pour la prédiction de la réponse des éléments soumis sous tension, prenant en compte la présence de fibres métalliques, est présentée. Des recherches expérimentales furent entreprises afin d'étudier le comportement de poutres sans étriers. L'influence de la présence de fibres sur le développement de fissures ainsi que les mécanismes de ductilité et de rupture est discutée. Les résultats montrent que l'ajout de fibres améliore la capacité portante et la ductilité des poutres. Une procédure est suggérée afin de déterminer la capacité portante de poutres construits avec BFM.

The 1994 CSA Standard requires that slab-column connections be designed for one-way shear and two-way shear action. Three full-scale slab and corner column specimens were constructed and tested to failure to investigate the influence of the size of corner column on the slab shear capacity. The current design provisions of the 1994 CSA Standard and EC2-02 were compared with the experimental results of the three specimens. The experimental results indicate that the predictions for one-way shear action are more accurate than the predictions for two-way shear action. The beneficial effects of increasing the column size in improving the shear capacity and mode of failure are demonstrated.

Precast concrete structures are not widely used in severe seismic regions due the limited knowledge of the response of these systems to reversed cyclic loading. A series of four precast concrete wall panels were tested to evaluate their response to reversed cyclic loading. These units represent the wall panels of a typical single storey precast concrete structure. In order to achieve improved ductility and energy absorption characteristic, it was found that the horizontal sliding of the wall panel along the grout-wall interface must be controlled. Due to the reversed cyclic loading and the increased wall panel participation from limiting the horizontal sliding of the wall, it was determined that shear reinforcement of each precast specimen was separated into three separate component parts, joint rotation, wall panel deformations and horizontal wall panel sliding, to compare and evaluate the seismic performance of the wall panels.

The reliability analysis of telecommunication networks requires an estimate of the probability of failure of antenna-supporting structures. Lacking such estimates, the network planners tend to assume that the probability of failure of towers is negligible. On the other hand, reliability concepts implicit in the codes are not always compatible with those used in reliability analysis of the network, in particular, the implicit probabilities associated with partial load and resistance factors are obtained for idealized structural members and do not address the reliability of the structure as a system. Advances in structural reliability, combined with more extensive climatologic data, can be used to implement a probabilistc approach for the design of towers. / The objective of this study is to propose a procedure for calculating the probability of mechanical failure of self-supported telecommunication towers. The procedure introduces the concept of calculating the conditional probability of failure which can be used with different joint distributions of wind and ice with a minimum of computations. As an example, the methodology is applied to the CEBJ tower in James Bay. The structure is assumed to behave linearly and to be statically determinate. In consequence, the structure can be modelled as a weakest link model. / The study demonstrates the possibility of estimating the probability of failure for the whole structure using a rational approach. The critical members of the structure and the relative importance of each of the design parameters with respect to the probability of failure are identified in order to simplify the reliability analysis. The probability of failure is most sensitive with respect to the joint probability distribution function of wind speed and ice thickness. Upper and lower bound estimates of the probability of failure are presented for different assumption in the joint distribution. These results indicate the need for a better model for the environmental loads.

Hydro-Quebec operates actually 476 hydraulic structures from which more than one-third are made out of concrete. Many of these structures show signs of aging which mainly consist of deterioration of concrete surfaces due to erosion and freeze-thaw cycles. Repair of these deteriorations requires the use of materials which are available from a wide variety of manufacturers. Most of the time informations on the various physico-mechanical properties of such repair materials are insufficient or unavailable. / This thesis, in addition to furnishing a complete guide on the repair materials and techniques of deteriorated concrete surfaces, gives the results obtained from the inquiry realized among various organizations around the world owners of hydraulic structures together with those from a laboratory study conducted on repair materials not tested previously by Hydro-Quebec. In this particular study, the following physico-mechanical properties were investigated: thermal compatibility with the concrete substrate, shrinkage, permeability, bond strength, compressive strength and freeze-thaw resistance. / The results of both the inquiry and the laboratory study show the following: (1) epoxies are not suitable for the repair of the concrete surfaces located on hydraulic structures; (2) cement mortars and latex-modified cement mortars are the repair materials which perform the best on hydraulic structures; (3) physico-mechanical properties of cement mortars are improved when they are subjected to a wet cure while those of the latex-modified cement mortars are when they are subjected to 24 hours wet cure followed by a dry one; (4) cement mortars are generally more thermal compatible with concrete substrates when compared to latex-modified cement mortars; (5) shrinkage, which is generally larger on latex-modified cement mortars, greatly influence the performance of repair mortars.

Smooth design spectra are generally used to describe the seismic excitation provided by the maximum design earthquake for safety evaluation of critical facilities located in Eastern Canada. However, a comprehensive study of the inelastic behaviour of critical structural systems requires step-by-step inelastic analysis in the time domain. / This thesis presents a study of inelastic seismic analysis of short-period structures subjected to ground motion acceleration time histories compatible with Eastern Canadian conditions and defined (i) from historical records scaled to the smooth design spectrum intensity, (ii) from spectrum-compatible accelerograms generated by random vibration theory, and (iii) from the modification of the Fourier Spectrum coefficients of historical records while preserving the original phase angles. The ductility demand, the input energy, the hysteretic energy, the number of yield events, and other performance indices, are examined in parametric analyses to identify the type of earthquake motions that is critical for earthquake resistant design of ductile short-period structures. The linear and cracking responses of concrete gravity dams of three different heights (90m, 45m, and 22.5m), that exhibit a brittle response to strong ground shaking, are also examined for the different types of spectrum-compatible accelerograms. It is generally concluded that in the absence of suitable spectrum-compatible historical accelerograms, either historical records with modified Fourier spectra or synthetic records can be used to evaluate the linear structural response. For nonlinear analysis, historical records with modified Fourier amplitude spectra tend to produce closer results to those obtained from real earthquakes for cumulative damage indices, as compared to the results computed from synthetic accelerograms.

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 uniform bond stress, enabled the study of both pullout failures and splitting failures. Variables studied included concrete cover, bar size and the effect 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 both the transfer and the flexural bond lengths. Equations for predicting the transfer and 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 cover and bar size and the presence of steel fibres is given. Equations are suggested to determine the transfer length and crack spacing. / Experimental investigations were carried out to study the post-cracking behaviour of beams 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-column 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 beams and two-way slabs, accounting for the presence of epoxy coatings, are given in a form suitable for implementation in codes of practice.

The objective of this study is to evaluate the effect of corrosion on the bond characteristics between the reinforcing steel and the surrounding concrete. / The results indicate that as the corrosion level increased, the tension stiffening of the concrete decreased and also the bond between the reinforcing steel and the concrete diminished considerably. Further, the comparison was made between the normal portland cement (NPC) concrete with a water-cement ratio (w/c) of 0.32, NPC concrete a with w/c ratio of 0.52 and NPC concrete with high volume (58% by total weight of cementitious materials) fly ash content, in terms of bond characteristics and corrosion resistance. It was found that as the w/c ratio increased, the corrosion resistance as well as the bond strength decreased and also the use of fly ash was very effective in improving the impermeability of the concrete and the bond between the reinforcing steel and concrete. (Abstract shortened by UMI.)

Carbon dioxide (CO2) emissions have been identified as a major contributor to climate change. Current CO2 mitigation efforts focus on the removal, recovery and disposal of CO2 at point sources. Finding beneficial uses of as-captured or recovered CO2 is a critical challenge in greenhouse gas mitigation. This thesis investigates the possibility of the beneficial use of carbon dioxide in precast concrete production and the performance, both short-term and long-term, of the concretes so produced. The calcium compounds in cementitious materials react readily with carbon dioxide to convert CO2 to thermodynamically stable carbonates. The reaction accelerates strength development and makes the technology appropriate for early age curing. Paste, mortar and concrete samples were examined to quantify such aspects as the carbon dioxide uptake, strength development, and durability of carbonated concrete. It was found that the uptake by the cementitious binders was significant. Compared to their theoretical capacity, cement could reach a carbonation degree of over 25% when treated as pastes and about 20% when used as a part of concrete. The study compared carbonation-cured and hydrated Portland cement concrete and slag cement concretes in terms of their early strength, late strength, weathering carbonation shrinkage, freeze/thaw durability, water absorption, and pH. The carbonated concrete was generally comparable, or superior, to the hydrated concrete except for the case of a 50% GGBF slag blend which had a slower strength development due to reduced secondary cementitious reaction. A second method of binding carbon into concrete was considered by carbonating ladle slag fines and us / Les émissions de dioxyde de carbone (CO2) contribuent de façon importante aux changements climatiques. Les efforts actuels de mitigation du CO2 se concentrent principalement sur la saisie, la récupération et le débarras du CO2 aux sources ponctuelles. Trouver des usages bénéfiques au CO2 tel que la capturé ou récupération représente un défi critique pour la mitigation des gaz à effet de serre. Cette thèse examine la possibilité d'utiliser le CO2 de façon bénéfique dans la production du béton préfabriqué, ainsi que la performance à court et à long termes du béton ainsi produit. Les composés calcaires dans le ciment réagissent avec le dioxyde de carbone pour convertir le CO2 en carbonates qui sont stables du point de vue thermodynamique. Cette réaction accélère le développement de la résistance du béton, ce qui rend la technologie appropriée pour des bétons à cure rapide. Des échantillons de pâte, de mortier et de béton ont été examinés pour tenter de quantifier certains aspects tels l'absorption du dioxyde de carbone, le développement de la résistance et la durabilité du béton carbonaté. L'absorption du CO2 par les liants dans le ciment fut importante. Comparé à leur capacité théorique, le ciment pourrait atteindre un degré de carbonation de plus de 25% quand il est préparé sous forme de pâte et de 20% quand il est utilisé dans le béton. L'étude a considéré des bétons composés de ciment Portland et de ciment de scories, curés de façon traditionnelle (hydratation) et curés par carbonatation, et a comparé leurs résistance après 7 jours, résistance après 56 jours, résistance à la contraction lors de la$

The main objective of this research was to create a finite element model for detailed three-dimensional stress analysis of an overhead optical ground wire (OPGW) typical of those used in transmission lines. The detailed model considers all possible mechanical effects, such as contact, friction, elongation, torsion, and bending for different end conditions. / The OPGW under study comprises four components: the external layer of fourteen aluminum alloy wires and ten inner aluminum clad steel wires, which are laid over an aluminum tube that houses a five-groove aluminum spacer. The optical fiber units are inserted in the aluminum spacer grooves. Three-dimensional solid elements are used to model the outer wires, the inner wires, and the aluminum spacer. The central aluminum tube is modeled with shell elements with large strain and deformation kinematics. All possible contacts between the components, with and without friction, are considered in the model. / The OPGW is assumed fixed at one end and pulled from the other with a prescribed displacement equivalent to the experimental elongation of 0.61% defined for all components. / The finite element analysis predicts that the responses of the outer and inner wires are in the linear range, however the aluminum tube and spacer are yielded under the prescribed displacement. Therefore, a multilinear stress-strain law is used in the model. / Two scenarios of loading were tested to apply the axial elongation on the wires; either only the central node or all the interior nodes of the wire cross sections are prescribed a maximum axial displacement. / Results of the finite element model are compared with those of the experiments performed at IREQ and with the analytical solutions of Machida and Durelli (1973) and Phillips and Costello (1973). The calculated axial forces of the cable in the coarse and fine mesh models are 61% and 70% of those predicted by the analytical solutions, respectively. However, the differences in stresses and strains of the coarse mesh model are in the range of ten percent only from the theoretical solutions. / The effective modulus of elasticity of the finite element model increases with tension. For the maximum elongation, the effective modulus obtained with the coarse and fine mesh models is 62% and 70% respectively of the equivalent modulus of elasticity calculated neglecting all three-dimensional effects. / This study shows the reliability and significance of using finite element modeling in predicting the detailed response of a complex cable, for which experiments and theoretical solutions are unable to yield complete results. (Abstract shortened by UMI.)