Search results for "Reinforced concrete"

Pumice concrete for structural wall panels

2003

Some properties of lightweight pumice stone concrete (LWPSC) are discussed, on account of a possible structural use of this material. Then the results of an experimental investigation are described, in order to show that pumice can really be considered an alternative to common artificial lightweight aggregates, taking into account the performance pointed out by loading tests carried out on structural systems made of LWPSC. Three different kinds of reinforced wall panels were made using LWPSC, lightweight expanded clay concrete and normal weight concrete; then their structural responses under horizontal cyclic and constant vertical forces were compared, above all with reference to lateral st…

Behavior of fiber-reinforced concrete columns under axially and eccentrically compressive loads

2010

An experimental investigation into the behavior of 16 short, confined, reinforced concrete columns with and without steel fibers was carried out. The columns with square sections had a concrete core 165 x 165 mm (6.49 x 6.49 in.) at the midsection and were hunched at the ends to apply eccentric loading and prevent boundary effects. The specimens were tested to failure at different strain rates under two loading schemes: concentric compression and eccentric compression with a constant eccentricity. The axial load and axial strains were obtained to evaluate the effects of the presence of steel fibers, the thickness of the cover concrete, and the eccentricity of the applied axial load. The com…

Shear strength of steel fiber reinforced concrete beams with stirrups

2006

The present paper proposes a semi-empirical analytical expression that is capable of determining the shear strength of reinforced concrete beams with longitudinal bars, in the presence of reinforcing fibers and transverse stirrups. The expression is based on an evaluation of the strength contribution of beam and arch actions and it makes it possible to take their interaction with the fibers into account. For the strength contribution of stirrups, the effective stress reached at beam failure was considered by introducing an effectiveness function. This function shows the share of beam action strength contribution on the global strength of the beam calculated including the effect of fibers. T…

Stress field model for strengthening of shear-flexure critical RC beams

2017

A model for the design of shear-flexure critical reinforced concrete elements strengthened with fiber-reinforced polymer (FRP) sheets and plates is presented. The model is based on the stress field approach and the equilibrium method and accounts for the different failure modes of FRP, focusing on the debonding of the FRP from the concrete surface. The efficiency of the model in the strength assessment of beams reinforced with FRP by the prediction of the shear-flexure capacity is checked by corroborating the results of several experimental tests found in the literature. Moreover, the presented model's capacity to reproduce experimental behavior is compared with the formulations suggested b…

Shear Capacity Model with Variable Orientation of Concrete Stress Field for RC Beams Strengthened by FRP with Different Inclinations

2021

A design-oriented analytical model able to evaluate the shear capacity of reinforced concrete (RC) beams strengthened with fiber-reinforced polymer (FRP) sheets or strips oriented in any direction is proposed. The formulation of the model is based on the variable-inclination stress-field approach, aiming to extend the provisions of current European standards to beams strengthened in shear using FRP. The main novelty of the model lies in taking into account the possible different inclination of steel stirrup and FRP reinforcement in determining the orientation of a compressed concrete stress field, and in shear strength evaluation, overcoming the approximation of the known models with variab…

Investigation on Application of Basalt Materials as Reinforcement for Flexural Elements of Concrete Bridges

2015

Basalt polymers are rather new materials for civil engineering; therefore, identification of peculiarities and limitations of application of such polymers in concrete structures (particularly bridges) is of vital importance. This paper experimentally investigates deformation behaviour and cracking of flexural elements, which are predominant parameters governing serviceability of the bridges. Unlike a common practice, the present study is not limited by the analysis of concrete beams reinforced with the polymer bars; it also considers effectiveness of basalt fibre reinforced polymer sheets for repairing the beams. The analysis has revealed that a combination of the high strength and elastici…

Effectiveness of stirrups and steel fibres as shear reinforcement

2004

This paper presents the results of experimental tests carried out on rectangular simply supported beams made of hooked steel fibre reinforced concrete with and without stirrups, subjected to two-point symmetrically placed vertical loads. The tests, carried out with controlled displacements, allow one to record complete load-deflection curves by means of which it is possible to deduce information on dissipative capacity and ductile behaviour up to failure. Depending on the amount of transverse reinforcement, volume fraction of fibres added in the mix and shear span, the collapse mechanism is due to predominant shear or flexure, thus showing the influence of the aforementioned structural para…

Behavior of fiber reinforced concrete-filled tubular columns in compression

2002

Experimental compression tests on steel tubular columns filled with plain concrete and fiber reinforced concrete are carried out. For each type of column three different lengths are considered in order to point out the influence of slenderness on the ductility in compression. The experimental investigations presented here have emphasized the improvement in ductility capacity obtained when fiber reinforced concrete is utilised instead of plain concrete. Moreover, the results obtained stress that the lateral displacements due to global instability are drastically reduced.

Size Effect in Compression of High Strength Fibre Reinforced Concrete Cylinders Subjected to Concentric and Eccentric Loads

2005

Simple Plastic Model for Shear Critical SFRC Beams

2010

A simple physical model, for prediction of ultimate shear strength of steel fiber reinforced concrete (SFRC) beams is developed on the basis of a plastic approach originally proposed for reinforced concrete (RC) beams without stirrups. It is founded on the hypothesis that cracks can be transformed into yield lines, and thus is know as Crack Sliding Model (CSM). First, the CSM is improved in order to take into account the shear strength increase for deep beams, due to the arch effect. Then, the effectiveness factors for fibrous concrete under biaxial stresses are evaluated, taking into account the post-cracking tensile strength of SFRC and its ability to control slippage along shear cracks. …