Ductility of Concrete Beams Reinforced with FRP Rebars

Abstract

Concrete beams reinforced with FRP rebars have greater durability than standard steel reinforced elements. The main disadvantage of using FRP rebars is the low ductility of elements which may be unacceptable in certain situations. There are several different ways of increasing the ductility of concrete elements, which are analyzed in this paper. They are compared based on efficiency, influence on durability and ease of construction. Less analyzed and tested methods are given more attention to try and expand the current knowledge and possibilities. For methods that lack experimental data, theoretical analysis is undertaken to assess the possible influence of that method on the increase in ductility. Ductility was obtained by calculating bending moment–curvature diagrams of cross sections for different reinforcement layouts. One method that lacks experimental data is confining the compressive area of beams with tensile FRP reinforcement. Theoretical analysis showed that confining the compressive area of concrete can significantly increase the ductility and bending capacity of beams. Since experimental data of beams reinforced with FRP rebars in tension and confined compressive area is sparse, some suggestions on the possible test setups are given to validate this theoretical analysis. Concrete beams reinforced with FRP can be detailed in such a way that they have sufficient ductility, but additional experimental research is needed.

Flexural Behavior of Concrete Box Girders Reinforced with Mixed Steel and Basalt Fiber-Reinforced Polymer Bars

“…Besides the strength demand, ductility and energy absorption are two important structural performance indices in design of modern concrete structures, and they have been emphasized as structural design requirements in most design codes. In this concern, the term "ductility" refers to the ability of structures to undergo inelastic deformation before failure without respectable drop in their strength or may refer to the ability of absorb energy without significant deterioration before failure [37][38]. In general, respect of the obtainable ductility of a structure is essential for the subsequent reasons: (a) to avoid brittle failure, (b) to employ dispersals of bending moments contradictory from that acquired from linear elastic structural analysis, in addition to (c) surviving a severe seismic activity as well as blast loading.…”

Simplified Rules for Serviceability Control of FRPRC Elements

“…In order to obtain more realistic values for the L/d ratio, a parametric analysis of single span, simply supported slabs was carried out. The calculations were made using a procedure made in VBA according to [6] (Kišiček et al [22,23] and Renić et al [24]). Slab thicknesses between 17.5 cm and 30 cm were considered, and spans varied between 4.0 and 8.0 m. The additional dead load was taken as 2.0 kN/m 2 and the live load, for residential buildings, was taken as 2.0 kN/m 2 .…”

Flexural Behavior of Steel Fiber Reinforced Concrete Beams: Probabilistic Numerical Modeling and Sensitivity Analysis

“…Different collapse definitions have been suggested in the literature. Some researchers define collapse by comparing the post-peak and peak loads (e.g., [32,33]). Such a definition is valid for structural elements that exhibit deflection-softening behavior.…”

“…Furthermore, other collapse definitions can be considered (e.g., [33]). Ductility can be expressed by comparing curvatures [32], energies [37] or displacements [38] at ultimate (i.e., collapse) and yield states. In this study, ductility is defined as the ratio between the collapse and the yield displacement, a definition often used for SFRC beams [12,33,39].…”