A model to simulate the moment–rotation and crack width of FRC members reinforced with longitudinal bars

Abstract

a b s t r a c tThe present work describes a model for the determination of the moment-rotation relationship of a cross section of fiber reinforced concrete (FRC) elements that also include longitudinal bars for the flexural reinforcement (R/FRC). Since a stress-crack width relationship ðr-wÞ is used to model the post-cracking behavior of a FRC, the r-w directly obtained from tensile tests, or derived from inverse analysis applied to the results obtained in three-point notched beam bending tests, can be adopted in this approach. For a more realistic assessment of the crack opening, a bond stress versus slip relationship is assumed to simulate the bond between longitudinal bars and surrounding FRC. To simulate the compression behavior of the FRC, a shear friction model is adopted based on the physical interpretation of the post-peak compression softening behavior registered in experimental tests. By allowing the formation of a compressive FRC wedge delimited by shear band zones, the concept of concrete crushing failure mode in beams failing in bending is reinterpreted. By using the moment-rotation relationship, an algorithm was developed to determine the force-deflection response of statically determinate R/FRC elements. The model is described in detail and its good predictive performance is demonstrated by using available experimental data. Parametric studies were executed to evidence the influence of relevant parameters of the model on the serviceability and ultimate design conditions of R/FRC elements failing in bending.

Influence of polypropylene fibers on the flexural behavior of reinforced concrete slabs with different opening shapes and sizes

“…Alternatively, steel fibers can be added to concrete in order to partially optimize and substitute conventional main steel reinforcement . Recently, the combination of steel fibers and conventional reinforcement bars is gaining popularity in several applications, being known under the name of hybrid RC 16‐23 …”

Prediction of the load carrying capacity of elevated steel fibre reinforced concrete slabs

“…This invalidates the use of strain as a state variable in constitutive laws for compressive concrete [41]. The post-peak behaviour of FRC in compression can be analysed by wedge sliding mechanism [38]. Nevertheless, due to the lack of longitudinal tensile reinforcement in the E-SFRC slab systems considered in the present work, the tensile crack localisation is the dominant failure mode of the FRC elements.…”

“…By following the recommendation of fib Model Code 2010 [35], when an element of FRC does not include conventional reinforcement, h L can be assumed equal to the height of its cross section. A layered model, capable of considering all the main mechanisms of a cracked FRC, was developed to predict the moment-rotation response of a nonlinear hinge[38].…”

Nonlinear analysis of reinforced concrete beams submitted to bending moment gradients considering the variable adhesion model

“…It is also important to emphasise the works of Abdel Baky et al [14], Lin and Zhang [15], Barros et al [16], Biscaia et al [17], Yan et al [18], Vilanova et al [19], Gooranorimi [20], Zhang et al [21] and Sturm and Visintin [22], who developed the bond-slip models for polymer-reinforced concrete elements. Zhan et al [23] developed a nonlinear finite element model, considering slippage in concrete-filled steel tube (CFST) beams.…”