Corrosion of steel reinforcement is one of the most severe problems of durability in reinforced concrete structures. A good understanding of the corrosion effects on the reinforcing steel mechanical properties is\ud necessary to adequately assess impaired structures. A study of the mechanical response of corroded reinforcement subjected to monotonic and cyclic loads by means of an experimental study is presented in this work. More than 180 corroded specimens, 40 monotonic and 140 fatigue tests were performed. Relationships between corrosion penetration and the mechanical properties of reinforcing steel bars were identified. In addition, a study of the influence of the pit geometry on the fatigue life was carried out. A\ud severe non-linear reduction in the mechanical properties studied, related to the corrosion degree was observed. These phenomena can provide relevant information for the assessment of existing structures\ud and for life cycle evaluation.Peer ReviewedPostprint (author's final draft

A conceptual model for the prediction of the shear-flexural strength of slender reinforced concrete beams with and without transverse reinforcement is presented. The model incorporates the shear transferred by the un-cracked concrete chord, along the crack's length, by the stirrups, if they are, and, in that case by the longitudinal reinforcement. After the development of the first branch of the critical shear crack, failure is considered to occur when the stresses at any point of the concrete compression chord reach the assumed biaxial stress failure envelope. A physical explanation is provided for the evolution of the shear transfer mechanisms, and the contribution of each one at ultimate limit state is formulated accordingly. Simple equations are derived for shear strength verification and for designing transverse reinforcement. The method is validated by comparing its predictions with the results of 1131 shear tests, obtaining very good results in terms of mean value and coefficient of variation. Because of its accuracy, simplicity and theoretical consistency, the proposed method is considered to be very useful for the practical design and assessment of concrete structures subjected to combined shear and bending.

A mechanical model previously developed by the authors for the prediction of the shear flexural strength of slender reinforced concrete beams with rectangular cross-section with or without stirrups has been extended to beams with T and I cross-sections. The effects of the section shape on each shear transfer action have been identified and incorporated into the corresponding equations. General expressions for strength verification and transverse reinforcement design have been derived. The contribution of the flanges to the shear strength is accounted for by means of an effective shear width, which depends on the section geometry and on the longitudinal reinforcement ratio. The effect of the vertical confinement stresses introduced by the shear reinforcement on the concrete web is also considered. The expressions derived are valid, as particular cases, for beams with inverted T or rectangular cross sections. The proposed equations have been checked with experimental results available in the literature, obtaining very good results. The simplicity, straightforwardness of application and the accuracy of the method make it suitable for daily engineering practice.Peer ReviewedPostprint (author's final draft