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This paper presents a model for evaluation of the rear face damage in concrete barriers subjected to impact of non‐deforming projectiles. This is an improved and extended version of a previously published model, which now covers both plain and steel fiber reinforced concrete (SFRC) barriers. The rear face damaged area commonly measured in tests is characterized by an equivalent diameter, evaluated by the model. Calibration and then validation are based on published experimental data. Different sets of experiments, of plain concrete and SFRC, reported by different researchers, were used for the model's calibration and for its validation. The calibrated model's predictions show reasonable agreement with the reported experimental results, especially in view of their considerable scatter. The main findings from a parametric study of the model's predictions refer to the influence on the rear face damage (at barrier thickness lower than the scabbing limit thickness) of including steel fibers in the concrete mix, the barrier thickness, impact level, and the projectile diameter. The model's predictions demonstrate the lower extent of damage in SFRC barriers, compared to plain concrete. The use of the model enables quantitative assessment of this damage and of its reduction in SFRC barriers. [ABSTRACT FROM AUTHOR]

This paper describes a work that examines a new solution to the problem that arises from the relatively high amount of transverse reinforcement required in HSC columns. It presents an alternative to common transverse steel reinforcement, a dual system comprising steel ties and a carbon-fiber mesh (CFM) applied internally together with steel ties. The behavior of the proposed system was examined in this work in a series of twelve laboratory tests of circular stub column specimens. The experiments performed in this work focused on the columns' load and displacement capacities. The tests were planned with the aid of an analytical model that was originally developed for a hybrid system of external fiber-reinforced polymer (FRP) sheets and internal steel, and was adapted for the current system. An analysis of the results shows that for a given amount of conventional transverse steel, the application of the carbon-fiber meshes adds efficiency to the rebar confinement system, in terms of both the load bearing capacity and the ductility, and for specimens with the hybrid confinement system, the higher the carbon fiber amount the larger the ductility improvement. Furthermore, fair to good agreement was observed between the model and the measured stress–strain curves, especially those of the peak stresses. Based on the above findings and the added benefit of fire resistance, the hybrid method appears to be promising for confining HSC columns. [ABSTRACT FROM AUTHOR]

This article presents an experimental study aimed to identify and quantify the cracking localization (CL) phenomenon in under‐reinforced R/SFRC beams. Results of current experiments together with those of previous tests published by the authors were used for quantification of the cracking localization level (CLL) considering the effect of fiber content, Vf, and of longitudinal reinforcement ratio, ρs, over a wide range of ρs and the effect of rebar yield and ultimate strengths. The experimental program consisted of four‐point bending tests of normal strength R/SFRC beam specimens with 400 and 500‐MPa steel and fiber volumetric contents Vf of 0.5 and 0.76%. A new definition is introduced for "significantly wide cracks" that yields a unique definition of the CLL when this phenomenon diminishes. Moreover, it is now proposed to change the definition of CLL. The study identified the existence of a transition point (TP), beyond which addition of fibers to the concrete mix do not affect CLL anymore. Observations from the experimental results prove the consistency of the newly proposed CLL definitions as well as the dependency of CL on both the amount and stress hardening of the tension steel. Their use enables a clear delineation of the CL phenomenon in R/SFRC beams. The importance of this finding refers to the reported decrease of flexural ductility in R/SFRC beams due to high CLL. Hence, the importance of the ability, achieved in the current findings, to quantify the conditions for TPs in various cases. [ABSTRACT FROM AUTHOR]