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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluating Shear Capacity of Concrete Girders with Deficient Shear Reinforcement

Ormberg, Grant 11 1900 (has links)
This study assesses the suitability of four sectional shear methods for predicting the shear capacity of reinforced concrete members which do not comply with S6-06 Section 14 stirrup spacing and area requirements. The results of the evaluations indicate that the sectional shear provisions in S6-06, AASHTO LRFD-05 and software Response 2000 appropriately account for variations in stirrup spacing and area detailing, and present with good agreement between predicted and tested shear capacities for member with deficient shear reinforcement. However, shear capacities calculated using ACI 318-08 do not agree well with tested capacities for members with less than minimum stirrups. Two modified shear methods are proposed, which revise the diagonal crack spacing and concrete contribution area assumed by S6-06. The modified shear methods improve predictions of shear capacity relative to predictions calculated using S6-06 and eliminate the issue of non-convergent shear capacity predictions which can result from evaluation using S6-06. / Structural Engineering
2

Evaluating Shear Capacity of Concrete Girders with Deficient Shear Reinforcement

Ormberg, Grant Unknown Date
No description available.
3

Behavior of circular concrete columns reinforced with FRP bars and stirrups / Comportement de colonnes circulaires en béton armé de barres et de cadres de PRF

Afifi, Mohammad January 2013 (has links)
The behavior of concrete members reinforced with fiber reinforced polymer (FRP) bars has been the focus of many studies in recent years. Nowadays, several codes and design guidelines are available for the design of concrete structures reinforced with FRP bars under flexural and shear loads. Meanwhile, limited research work has been conducted to examine the axial behavior of reinforced concrete (RC) columns with FRP bars. Due to a lack of research investigating the axial behavior of FRP reinforced concrete columns, North American codes and design guidelines do not recommend using FRP bars as longitudinal reinforcement in columns to resist compressive stresses. This dissertation aims at evaluating the axial performance of RC compression members reinforced with glass FRP (GFRP) and carbon FRP (CFRP) bars and stirrups through experimental and analytical investigations. A total of twenty seven full scale circular RC specimens were fabricated and tested experimentally under concentric axial load. The 300 mm diameter columns were designed according to CAN/CSA S806-12 code requirements. The specimens were divided to three series; series I contains three reference columns; one plain concrete and 2 specimens reinforced with steel reinforcement. Series II contains 12 specimens internally reinforced with GFRP longitudinal bars and transverse GFRP stirrups, while series III includes specimens totally reinforced with CFRP reinforcement. The experimental tests were performed at the structural laboratory, Faculty of Engineering, University of Sherbrooke. The main objective of testing these specimens is to investigate the behavior of circular concrete columns reinforced with GFRP or CFRP longitudinal bars and transverse hoops or spirals reinforcement. Several parameters have been studied; type of reinforcement, longitudinal reinforcement ratio, the volumetric ratios, diameters, and spacing of spiral reinforcement, confinement configuration (spirals versus hoops), and lap length of hoops. The test results of the tested columns were presented and discussed in terms of axial load capacity, mode of failure, concrete, longitudinal, and transverse strains, ductility, load/stress-strain response, and concrete confinement strength through four journal papers presented in this dissertation. Based on the findings of experimental investigation, the GFRP and CFRP RC columns behaved similar to the columns reinforced with steel. It was found that, FRP bars were effective in resisting compression until after crushing of concrete, and contributed on average 8% and 13% of column capacity for GFRP and CFRP RC specimens, respectively. Also, the use of GFRP and CFRP spirals or hoops according to the provisions of CSA S806-12 yielded sufficient restraint against the buckling of the longitudinal FRP bars and provided good confinement of the concrete core in the post-peak stages. The axial deformability (ductility) and confinement efficiency can be better improved by using small FRP spirals with closer spacing rather than larger diameters with greater spacing. It was found that, ignoring the contribution of FRP longitudinal bars in the CAN/CSA S806-12 design equation underestimated the maximum capacity of the tested specimens. Based on this finding, the design equation is modified to accurately predict the ultimate load capacities of FRP RC columns. New factors ?[indice inférieur g] and ?[indice inférieur c] were introduced in the modified equation to account for the GFRP and CFRP bars compressive strength properties as a function in their ultimate tensile strength. On the other hand, proposed equations and confinement model were presented to predict the axial stress-strain behavior of FRP RC columns confined by FRP spirals or hoops. The model takes into account the effect of many parameters such as; type of reinforcement, longitudinal reinforcement ratio; transverse reinforcement configuration; and the volumetric ratio. The proposed model can be used to evaluate the confining pressure, confined concrete core stress, corresponding concrete strain, and stress-strain relationship. The results of analysis using the proposed confinement model were compared with experimental database of twenty four full-scale circular FRP RC columns. A good agreement has been obtained between the analytical and experimental results. Proposed equations to predict both strength and stress-strain behavior of confined columns by FRP reinforcements demonstrate good correlation with test data obtained from full-scale specimens.
4

Shear Behaviour of Slender RC Beams with Corroded Web Reinforcement

Alaskar, Abdulaziz January 2013 (has links)
This research study examined the effect of corrosion of web reinforcement (stirrups) on the shear behaviour of slender reinforced concrete (RC) beams. The experimental program consisted of seventeen slender shear-critical RC beams: five uncorroded and twelve corroded beams. The test variables included: 1) corrosion level (0%, 7.5% and 15%); 2) type of stirrups (smooth and deformed); 3) stirrup diameter (D6, D12 and 10M); 4) stirrups spacing (100mm and 200mm); and 5) the presence of CFRP repair. The corroded beams had their stirrups subjected to corrosion using an accelerated corrosion technique and the mass loss in the stirrups was estimated based on Faraday’s law. All of the beams were monotonically tested to failure in three point bending. The corrosion cracks formed were parallel to the locations of stirrups as evidence of the corrosion damage in the corroded beams. The maximum decrease in the ultimate shear strength ranged from 11% to 14.4% for beams with high corrosion level of 15.6% mass loss. At a low corrosion level (4.39% mass loss), the shear strength of beams with smooth stirrups increased up to 35% due to the enhancement of shear friction at the concrete-corroded stirrups interface. The stiffness of the corroded beams was enhanced in comparison to the control beams. The ultimate deflection of the corroded beams was decreased up to 25% in comparison to the control beams. The CFRP repair increased the shear strength by 36% and improved the overall stiffness by 39% in comparison to the corroded unrepaired beams. All of the unrepaired beams failed in diagonal tension splitting, while the CFRP repaired corroded beams failed in diagonal tension splitting in addition to debonding of the FRP or concrete cover delamination. The actual corrosion mass loss results were in good correlation with Faraday’s law for the D12 and 10M stirrups. Poor correlation between actual and estimated mass loss was obtained for D6 smooth stirrups, possibly due to errors in the impressed corrosion. iv The analytical model used the modified compression field theory (MCFT) to predict the shear strength of uncorroded and corroded slender RC beams. In the corroded beams, two reduction factors were added to the MCFT model including the mass loss factor and the effective web width. Predictions based on the model revealed that the control beams gave a very good correlation with the ratio of experimental to predicted values that ranged from 0.94 to 1.02. On other hand, the ratio of experimental to predicted strength in the corroded beams ranged between1.06 to 1.4. The poor correlations were obtained for the beams with the D6 smooth stirrups. This study demonstrates that corrosion of web reinforcement can have a detrimental effect on the shear strength and ductility of slender shear-critical RC beams. The experimental results and analytical approach will be very useful for practicing engineers and researchers dealing with corrosion damage in slender RC members.
5

Seismic Behaviour of Exterior Beam-Column Joints Reinforced with FRP Bars and Stirrups

Mady, Mohamed Hassan Abdelhamed 25 August 2011 (has links)
Reinforced concrete beam-column joints (BCJs) are commonly used in structures such as parking garages, multi-storey industrial buildings and road overpasses, which might be exposed to extreme weathering conditions and the application of de-icing salts. The use of the non-corrodible fiber-reinforced polymer (FRP) reinforcing bars in such structures is beneficial to overcome the steel-corrosion problems. However, FRP materials exhibit linear-elastic stress-strain characteristics up to failure, which raises concerns on their performance in BCJs where energy dissipation, through plastic behaviour, is required. The objective of this research project is to assess the seismic behaviour of concrete BCJs reinforced with FRP bars and stirrups. An experimental program was conducted at the University of Manitoba to participate in achieving this objective. Eight full-scale exterior T-shaped BCJs prototypes were constructed and tested under simulated seismic load conditions. The longitudinal and transversal reinforcement types and ratios for the beam and the columns were the main investigated parameters. The experimental results showed that the GFRP reinforced joints can successfully sustain a 4.0% drift ratio without any significant residual deformation. This indicates the feasibility of using GFRP bars and stirrups as reinforcement in the BCJs subjected to seismic-type loading. It was also concluded that, increasing the beam reinforcement ratio, while satisfying the strong column-weak beam concept, can enhance the ability of the joint to dissipate seismic energy. An analytical investigation was conducted through constructing a finite element model using ANSYS-software. The model was verified against the experimental results in this research. Then, a parametric study was performed on number of different parameters known to affect such joints including column axial load, concrete compressive strength, flexural strength ratio and joint transverse reinforcement. It was concluded that 70% of the column axial load capacity can be recommended as an upper limit to the applied axial loads on the column to avoid damage occurrence within the joint. It was also concluded that a minimum flexural strength ratio of 1.50 is recommended to ensure the strong-column weak-beam mechanism. In addition, a minimum joint transverse reinforcement ratio of 0.60% is recommended to insure that the failure will not occur in the joint zone.
6

Seismic Behaviour of Exterior Beam-Column Joints Reinforced with FRP Bars and Stirrups

Mady, Mohamed Hassan Abdelhamed 25 August 2011 (has links)
Reinforced concrete beam-column joints (BCJs) are commonly used in structures such as parking garages, multi-storey industrial buildings and road overpasses, which might be exposed to extreme weathering conditions and the application of de-icing salts. The use of the non-corrodible fiber-reinforced polymer (FRP) reinforcing bars in such structures is beneficial to overcome the steel-corrosion problems. However, FRP materials exhibit linear-elastic stress-strain characteristics up to failure, which raises concerns on their performance in BCJs where energy dissipation, through plastic behaviour, is required. The objective of this research project is to assess the seismic behaviour of concrete BCJs reinforced with FRP bars and stirrups. An experimental program was conducted at the University of Manitoba to participate in achieving this objective. Eight full-scale exterior T-shaped BCJs prototypes were constructed and tested under simulated seismic load conditions. The longitudinal and transversal reinforcement types and ratios for the beam and the columns were the main investigated parameters. The experimental results showed that the GFRP reinforced joints can successfully sustain a 4.0% drift ratio without any significant residual deformation. This indicates the feasibility of using GFRP bars and stirrups as reinforcement in the BCJs subjected to seismic-type loading. It was also concluded that, increasing the beam reinforcement ratio, while satisfying the strong column-weak beam concept, can enhance the ability of the joint to dissipate seismic energy. An analytical investigation was conducted through constructing a finite element model using ANSYS-software. The model was verified against the experimental results in this research. Then, a parametric study was performed on number of different parameters known to affect such joints including column axial load, concrete compressive strength, flexural strength ratio and joint transverse reinforcement. It was concluded that 70% of the column axial load capacity can be recommended as an upper limit to the applied axial loads on the column to avoid damage occurrence within the joint. It was also concluded that a minimum flexural strength ratio of 1.50 is recommended to ensure the strong-column weak-beam mechanism. In addition, a minimum joint transverse reinforcement ratio of 0.60% is recommended to insure that the failure will not occur in the joint zone.
7

Shear Behaviour of Slender RC Beams with Corroded Web Reinforcement

Alaskar, Abdulaziz January 2013 (has links)
This research study examined the effect of corrosion of web reinforcement (stirrups) on the shear behaviour of slender reinforced concrete (RC) beams. The experimental program consisted of seventeen slender shear-critical RC beams: five uncorroded and twelve corroded beams. The test variables included: 1) corrosion level (0%, 7.5% and 15%); 2) type of stirrups (smooth and deformed); 3) stirrup diameter (D6, D12 and 10M); 4) stirrups spacing (100mm and 200mm); and 5) the presence of CFRP repair. The corroded beams had their stirrups subjected to corrosion using an accelerated corrosion technique and the mass loss in the stirrups was estimated based on Faraday’s law. All of the beams were monotonically tested to failure in three point bending. The corrosion cracks formed were parallel to the locations of stirrups as evidence of the corrosion damage in the corroded beams. The maximum decrease in the ultimate shear strength ranged from 11% to 14.4% for beams with high corrosion level of 15.6% mass loss. At a low corrosion level (4.39% mass loss), the shear strength of beams with smooth stirrups increased up to 35% due to the enhancement of shear friction at the concrete-corroded stirrups interface. The stiffness of the corroded beams was enhanced in comparison to the control beams. The ultimate deflection of the corroded beams was decreased up to 25% in comparison to the control beams. The CFRP repair increased the shear strength by 36% and improved the overall stiffness by 39% in comparison to the corroded unrepaired beams. All of the unrepaired beams failed in diagonal tension splitting, while the CFRP repaired corroded beams failed in diagonal tension splitting in addition to debonding of the FRP or concrete cover delamination. The actual corrosion mass loss results were in good correlation with Faraday’s law for the D12 and 10M stirrups. Poor correlation between actual and estimated mass loss was obtained for D6 smooth stirrups, possibly due to errors in the impressed corrosion. iv The analytical model used the modified compression field theory (MCFT) to predict the shear strength of uncorroded and corroded slender RC beams. In the corroded beams, two reduction factors were added to the MCFT model including the mass loss factor and the effective web width. Predictions based on the model revealed that the control beams gave a very good correlation with the ratio of experimental to predicted values that ranged from 0.94 to 1.02. On other hand, the ratio of experimental to predicted strength in the corroded beams ranged between1.06 to 1.4. The poor correlations were obtained for the beams with the D6 smooth stirrups. This study demonstrates that corrosion of web reinforcement can have a detrimental effect on the shear strength and ductility of slender shear-critical RC beams. The experimental results and analytical approach will be very useful for practicing engineers and researchers dealing with corrosion damage in slender RC members.
8

Determinación y diseño del tipo de cimentación profunda con pilotes en puentes sobre suelos arenosos en Tumbes mediante un modelo computarizado / Determination and design of the type of deep foundation with pilots on bridges over sandy soils in Tumbes using a computerized model

Orellana Castillo, Javier Steven, Paitán Alejos, Juan Pablo 09 July 2020 (has links)
En el año 2017, Perú sufrió el fenómeno del Niño Costero luego de 19 años. Este desastre afectó principalmente la costa norte del país, ocasionando que numerosas viviendas e instalaciones terminaran enterradas por las inundaciones. Además, varios puentes colapsaron causando que pueblos queden incomunicados. A raíz de ello, se puede determinar que no todos los puentes están preparados para este tipo de fenómenos, teniendo como posibles causas estudios de suelos y diseños estructurales con escasa información. Por tales motivos, la presente tesis se refiere al diseño y determinación del tipo de pilote para la cimentación profunda más eficiente en puentes sobre suelos arenosos en Tumbes mediante un modelo computarizado. La aplicación se realizará en el puente Canoas, en el cual se buscará optimizar el rendimiento de ejecución considerando que pueda soportar las cargas actuantes y las características del suelo. Se propondrá un diseño alternativo para la superestructura que junto con una cimentación profunda con pilotes analizados será un proyecto óptimo tiempo de construcción, sin descuidar la capacidad resistente y costo. Esta propuesta consta de un puente de 50m de luz con vigas metálicas que presenta estribos de 16 m de altura en cada apoyo. Estos estribos tienen un encepado con 12 pilotes cada uno tipo CPI-8 con barrena de hélice continua (CFA). El diseño de la superestructura se realizará en SAP2000, los estribos serán en GEO5 y los pilotes se diseñarán por dos métodos (FHWA 1999 y analítico) comprobando su resistencia grupal con la eficiencia del grupo de 12 pilotes. / In 2017, Peru suffered the phenomenon of the Coastal Child after 19 years. This disaster mainly hit the north coast of the country, causing numerous homes and facilities to end up buried by flooding. In addition, several bridges collapsed causing villages to go intocommunicado. As a result, it can be determined that not all bridges are prepared for this type of phenomenon, taking as possible causes soil studies and structural designs with little information. For these reasons, this thesis refers to the design and determination of the type of pilot for the most efficient deep foundation in bridges on sandy soils in Tumbes using a computerized model. The application will be carried out on the Canoas bridge, in which it will be sought to optimize the execution performance considering that it can withstand the actuating loads and characteristics of the ground. An alternative design will be proposed for the superstructure that together with a deep foundation with analyzed piles will be an optimal construction time project, without neglecting the resilient capacity and cost. This proposal consists of a 50m light bridge with metal beams that presents 16 m high stirrups in each support. These stirrups have a brush with 12 piles each type CPI-8 with continuous propeller auger (CFA). The superstructure design will be done in SAP2000, the stirrups will be in GEO5 and the piles will be designed by two methods (FHWA 1999 and analytical) checking their group resistance with the efficiency of the group of 12 piles. / Tesis
9

Enrichissement des poutres multifibres pour le calcul des contraintes transversales et la prise en compte du confinement dans les sections en béton armé / Enhancement of multifiber beam elements in the case of reinforced concrete structures for taking into account the lateral confinement of concrete due to stirrups

Khoder, Natalia 12 December 2018 (has links)
Pour déterminer la vulnérabilité sismique des structures en béton armé, des méthodes de calcul numérique à l’échelle structurelle, effiaces et suffisamment précises, sont nécessaires. Des formulations d’éléments finis bidimensionnels ou tridimensionnels, largement utilisées, fournissent des résultats fiables. Cependant, ces types de méthodes impliquent un grand nombre de degrés de liberté et des lois de comportement robustes 3D pour le béton et l’acier, afin de capturer avec précision les non-linéarités dans les éléments élancés de structure en béton armé. Une autre méthode plus pratique dans le domaine de l’ingénierie des structures est l’utilisation des éléments de poutres multifibres. C’est la méthode adoptée dans ce travail de thèse.Les éléments poutres multifibres permettent de discrétiser la structure à l’aide d’éléments linéiques qui portent une section discrétisée dans le sens transversal en faisant l’hypothèse de cinématique d’Euler Bernoulli ou Timoshenko. La discrétisation de la section permet d’utiliser simplement des lois de comportement non linéaires et de modéliser des sections composites comme le béton armé. Néanmoins, il existe des limitations à ce genre de modèle. Ainsi, plusieurs recherches ont été menées, ces dernières années pour enrichir les éléments poutres afin de reproduire correctement les effets de cisaillement surtout dans le cas de poutres peu élancées où l’effet de cisaillement est non négligeable. Comme l’approche proposée par [VEC 88] adéquate pour les chargements bidimensionnels mais ne reproduisant pas l’effet de torsion, celle présentée par [LEC 12], mais dont le modèle ne peut pas être appliqué aux éléments en béton armé, et la formulation numérique de [MOH 10] qui est adaptée aux applications en béton armé mais ne fonctionne qu’en 2D. Plus récemment ([CAP 16b]; [CAP 16a]) et son équipe ont développé une technique adaptée au béton armé, qui prend en compte le gauchissement de la section et permet de calculer un état de déformation dans les fibres de béton sous des sollicitations 3D. Dans les travaux cités plus haut, soit les cadres d’armatures transversales ne sont pas du tout pris en compte, soit ils le sont de manière trop approximative. Cependant, comme le montrent certains essais expérimentaux menés par [CUS 95], la quantité de ferraillage transversal déclenche de manière significative le comportement des éléments structuraux, notamment sous chargement cyclique.Basé sur les travaux de [LEC 12] et [CAP 16a], ce travail de thèse vise à modéliser l’effet des armatures transversales sur le comportement du béton. La démarche proposée est d’enrichir les éléments finis poutres multifibres pour prise en compte de la distorsion de la section. Pour cela, des déplacements transversaux additionnels sont introduits. L’application du principe des puissances virtuelles sur le champ de vitesse virtuel associé permet de projeter les équations d’équilibre de l’élément et ainsi d’obtenir l’équation d’équilibre classique de l’élément mais aussi l’équilibre de la section. Cette dernière permet donc de tenir compte de l’effet des armatures transversales et de calculer correctement les contraintes latérales appliquées à chaque fibre de béton. En outre, afin de pouvoir reproduire l’effet de confinement des fibres de béton par les cadres, une loi de comportement dilatante doit être attribuée au béton. Dans ce contexte, la loi de comportement du µ modèle a été choisie. Celle-ci est dépourvue du comportement dilatant. Pour cette raison, une méthode d’introduction de la dilatance au niveau du coefficient de poisson est présentée dans ce mémoire. Les éléments poutres multifibres enrichis 2D et 3D sont formulés en déplacement et sont basés sur le modèle poutre de Caillerie [CAI 15] avec des fonctions de formes d’ordre supérieur. La pertinence de ces deux approches est finalement démontrée en confrontant la réponse du modèle numérique à différents résultats expérimentaux de la littérature. / In order to determine the seismic vulnerability of reinforced concrete structures, effective and sufficiently accurate numerical methods are required. Two-dimensional or three-dimensional finite element methods, widely used, provide reliable results. However, these types of methods involve a large number of degrees of freedom and robust 3D behavioral laws for concrete and steel to accurately capture the non-linearities in slender reinforced concrete elements. Another more practical method, in the field of structural engineering, is the use of multifiber beam elements.By using multifiber beam elements, the structure can be discretized with linear elements that carry a section discretized in the transversal direction based on the kinematic assumption of Euler Bernoulli or Timoshenko. The discretization of the section makes it possible to simply use nonlinear behavior laws and to model composite sections such as reinforced concrete. Nevertheless, there are limitations to this kind of model. Therefore, several researches have been conducted in the past few years to enhance the kinematics of the beam elements in order to correctly reproduce the shearing effects, especially in the case of short beams where the latter effect is not negligible. Several approaches have been developed in this field, as the one proposed by [VEC 88] adequate for two-dimensional case studies but doesn’t reproduce the torsional effect, the approach presented by [LEC 12], but whose model can not be applied to reinforced concrete elements, and the formulation proposed by [MOH 10] which is suitable for reinforced concrete applications but works only in 2D. More recently ([CAP 16b]; [CAP 16a]) have developed an enhanced multifiber beam model adapted to reinforced concrete elements and takes into account the warping of the section. The combination of this beam element with a concrete behavior model such as the µ model [MAZ 13], provides robust results with interesting computational speed. However, as shown by some experimental tests [CUS 95], the amount of transverse reinforcement triggers significantly the behavior of the beam elements, especially under cyclic loading . In the previous works, these reinforcements are neglected or considered in an approximative manner.Based on the work of [LEC 12] and [CAP 16a], this thesis aims to model the effect of transversal reinforcement. The approach proposed herein is to enhance the multifiber beam elements in order to take into account the distortion of the section. For this purpose, additional transverse displacements are introduced. The application of the principle of virtual powers on the field of associated virtual velocity leads to project the equilibrium equations of the element and thus to obtain the classical equilibrium equation of the element as well as the equilibrium of the section. The latter one allows to take into account the effect of the transverse reinforcements and to correctly calculate the lateral stresses applied to each concrete fiber. Moreover, in order to be able to reproduce the confinement effect due to the presence of stirrups, a dilatant constitutive law has to be attributed to the concrete fibers at the section level. In this context, the Mu model has been chosen even though it’s not a dilatant model. For this reason, a method of introducing dilatancy at the level of the Poisson’s coefficient is presented in this work. The 2D and 3D enhanced multifiber displacement beam models are formulated based on the Caillerie beam element [CAI 15] with higher order interpolation functions. The performance of these two approaches is also demonstrated by comparing the numerical model response to different experimental results of the literature.
10

Shear Behaviour of Disturbed Regions in Reinforced Concrete Beams with Corrosion Damaged Shear Reinforcement

Suffern, Christopher Andrew January 2008 (has links)
Corrosion of reinforcing steel is a major problem facing infrastructures owners with billions of dollars spent in repairing our aging infrastructure. One of the first steps in the repair process is to quantify the strength degradation in a reinforced concrete element caused by the corrosion of reinforcing steel. An understanding of the forces involved in the load carrying mechanisms is imperative; the transfer of shear forces in reinforced concrete beams is one of these load carrying mechanisms. The shear transfer mechanism is different near the end of beams, adjacent to point loads, and near changes in cross section. These regions are known as disturbed regions. Structural engineers have a good understanding of the shear transfer mechanism in disturbed regions. However, the effects of corroded shear reinforcement in these regions have not been widely investigated. The current study is comprised of an experimental program and analytical strut and tie modeling aimed at quantifying the strength reduction that occurs in disturbed regions of reinforced concrete beams with corroded shear reinforcement. The feasibility of strengthening a beam with dry lay-up carbon fibre reinforced polymer (CFRP) to repair the damage caused by corrosion of the shear reinforcement was also investigated. In the experimental study, a total of 16 reinforced concrete beams were cast. The specimens were 350 mm deep, 125 mm wide and 1850 mm long. Three shear-span to depth ratios (1.0, 1.5, 2.0) were selected. Each specimen was reinforced in flexure with two 25M bars and the shear reinforcement was 10M spaced at 150 mm on centre. The specimens were corroded for 21 days, 60 days, and 120 days corresponding to low, medium, and high corrosion levels. In addition, three specimens were constructed without shear reinforcement in the shear-span in order to compare the results from the corroded specimens. One specimen was also corroded to a high level and repaired with dry lay-up CFRP. The specimens were corroded using an accelerated corrosion technique. There was evidence of cracking of the cover concrete in all specimens, and in the more severely corroded specimens delamination of the cover concrete was recorded. The stiffness of the corroded specimens was less than their corresponding control specimen, and a strength reduction was evident in most specimens. The maximum recorded strength reduction was 52% compared to the companion uncorroded specimen. It was revealed that a more critical case occurs when the corroded shear reinforcement was shifted during placement or was inclined closer to the direction of the compressive force flow. Also, it was observed that the corroded shear reinforcement still provides limited ductility in comparison to the un-corroded reinforcement. A strut and tie model was developed based on the experiments to explain the behaviour of disturbed regions with corroded shear reinforcement. The model consisted of direct and indirect struts. The effects of corrosion were expressed in terms of a reduction in the stirrup cross-section, a reduction of compressive strength due to corrosion cracking, and a reduction in the concrete cross section width. It was hypothesized that the corrosion crack width influences the concrete compressive strength in the strut; consequently, a mathematical model was developed that related the reduction in concrete compressive strength with corrosion crack width. Also, a relationship between reinforcing steel mass loss and corrosion crack width was utilized from the published literature. An effective cross section width was obtained by reducing the width by the damaged concrete cover. The results from these models were input into a strut and tie model as a reduction in concrete compressive strength. The output from the strut and tie model was the ultimate shear strength of the specimen. The developed models were compared with a model from the literature and compared with the experimental results. The major contribution of this research is to allow designers to analyze disturbed regions with corroded shear reinforcement and determine the strength degradation; subsequently, one can determine what strengthening procedure would be most appropriate.

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