IJERT-Experimental Investigation on HPFRC Beams Subjected to Cyclic Loading (original) (raw)
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Flexural behaviour of High-performance concrete beams under Cyclic loading conditions
Journal of Engineering Research, 2022
Flexural behaviour of high-performance concrete (HPC) was affected by various parameters and plays a vital role in the strength of concrete. Present study aims in deciphering the role of cyclic loading on HPC reinforced with steel fibers. The study was carried out by casting of beams with hooked end steel fiber reinforced concrete with various grades (M60, M80, M100) and with admixtures (GGBS and Silica fume). Cast beams were studied for compressive strength, tensile strength, and flexural strength under cyclic loading. The study shows that there was a significant increase in compressive strength of HPC mixed with 1.0% of steel fiber. Flexural strength was found to be comparatively higher (upto 15% for all grades) for 1.25% steel fiber mixed HPC. Direct tensile strength is found to be higher than split tensile strength. Addition of steel fiber in HPC beam under cyclic loading, resulting in delayed or late development of cracks with decreased crack size.
Advances in Engineering Software, 2009
In the design of reinforced concrete structures, a designer must satisfy not only the strength requirements but also the serviceability requirements, and therefore the control of the deformation becomes more important. To ensure serviceability criterion, it is necessary to accurately predict the cracking and deflection of reinforced concrete structures under service loads. For accurate determination of the member deflections, cracked members in the reinforced concrete structures need to be identified and their effective flexural and shear rigidities determined. The effect of concrete cracking on the stiffness of a flexural member is largely dependent on both the magnitude and shape of the moment diagram, which is related to the type of applied loading. In the present study, the effects of the loading types and the reinforcement ratio on the flexural stiffness of beams has been investigated by using the computer program developed for the analysis of reinforced concrete frames with members in cracked state. In the program, the variation of the flexural stiffness of a cracked member has been obtained by using ACI, CEB and probability-based effective stiffness model. Shear deformation effect is also taken into account in the analysis and the variation of shear stiffness in the cracked regions of members has been considered by employing reduced shear stiffness model available in the literature. Comparisons of the different models for the effective moment of inertia have been made with the reinforced concrete test beams. The effect of shear deformation on the total deflection of reinforced concrete beams has also been investigated, and the contribution of shear deformation to the total deflection of beam have been theoretically obtained in the case of various loading case by using the developed computer program. The applicability of the proposed analytical procedure to the beams under different loading conditions has been tested by a comparison of the analytical and experimental results, and the analytical results have been found in good agreement with the test results.
Behaviour of Steel Fibre Reinforced Concrete Beam under Cyclic Loading
This paper describes the influence of steel fibre distribution on the ultimate strength of concrete beams. An experimental & analytical investigation of the behaviour of concrete beams reinforced with conventional steel bars and steel fibres under cyclic loading is presented. It is now well established that one of the important properties of steel fibre reinforced concrete (SFRC) is its superior resistance to cracking and crack propagation. As a result of this ability to arrest cracks, fibre composites possess increased extensibility and tensile strength, both at first crack and at ultimate load and the fibres are able to hold the matrix together even after extensive cracking. The net result of all these is to impart to the fibre composite pronounced postcracking ductility which is unheard of in ordinary concrete. The transformation from a brittle to a ductile type of material would increase substantially the energy absorption characteristics of the fibre composite and its ability to withstand repeatedly applied, shock or impact loading. Tests on conventionally reinforced concrete beam specimens, containing steel fibres in different proportions, have been conducted to establish loaddeflection curves. It was observed that SFRC beams showed enhanced properties compared to that of RC beams with steel fibres. The experimental investigations are validated with the analytical studies carried out by finite element models using ANSYS.
Experimental Investigation of the Deformation Behavior of SFRC Beams with an Ordinary Reinforcement
Mechanics of Composite Materials, 2014
The paper reports test results for steel-fiber-reinforced concrete beams. Four-point bending tests on 12 full-scale beams (with longitudinal reinforcement ratios of 0.3 and 0.6%) were carried out to investigate the postcracking behavior of the members. The content of fibers, spaced at equal intervals, ranged from 0 to 120 kg/m 3 , resulting in the amount of 0, 0.5, 1.0, and 1.5% by volume. A simple deflection analysis technique based on a linear interpolation between the cracking and yielding points is discussed. It is shown that this technique adequately assesses the bending moment at yielding, but significantly overestimates the corresponding deflections. It is concluded that the model discussed should be improved by taking into account the tension stiffening effect.
Experimental investigation of steel fiber-reinforced concrete beams under cyclic loading
International Journal of Advanced Structural Engineering, 2018
An experimental study has been conducted to study the cyclic behavior of reinforced concrete beams in which steel fibers were added to the concrete mix. Seven similar geometrically specimens in full scale were studied under four-point bending test in the form of slow cyclic loading. One sample as a control specimen was made without steel fibers or 0% volume fraction (vf) and six other samples with 1, 2 and 4% vf of steel fibers in twin models. The maximum and ultimate resistance, ductility, degradation of loading and unloading stiffness, absorption and dissipation of energy and equivalent viscous damping were studied in this investigation and the effect of steel fibers on the cyclic behavior was compared with each other. Generally, the addition of steel fibers up to a certain limit value (vf = 2%) improves the cyclic behavior of reinforced concrete beams and results in the increase of maximum strength and ultimate displacement.
Load-deflection Characteristics of Steel, Polypropylene and Hybrid Fiber Reinforced Concrete Beams
Concrete is the most widely used construction material because of its specialty of being cast into ductility and energy absorption capacity. Fiber reinforced concrete possesses high flexural and tensile strength, improved ductility, and high energy absorption over the conventional concrete in sustaining dynamic loads. The aim of this paper is to compare the properties of concrete beams in which three types of fibers are added individually. Steel fibers, polypropylene fibers and hybrid fibers were added to concrete in the volumetric ratio of four percentages in the preparation of four beam specimens. The fourth specimen had no fibers and acted as a control specimen. The dimensions of the beam specimens were 150 mm × 150 mm × 700 mm. The reinforced concrete beams of M30 grade concrete were prepared for casting and testing. Various parameters such as load carrying capacity, stiffness degradation, ductility characteristics and energy absorption capacity of FRC beams were compared with that of RC beams. The companion specimens were cast and tested to study strength properties and then the results were compared. All the beams were tested under three point bending under Universal Testing Machine (UTM). The results were evaluated with respect to modulus of elasticity, first crack load, ultimate load, and ultimate deflection. The test result shows that use of hybrid fiber improves the flexural performance of the reinforced concrete beams. The flexural behavior and stiffness of the tested beams were calculated, and compared with respect to their load carrying capacities. Comparison was also made with theoretical calculations in order to determine the load-deflection curves of the tested beams. Results of the experimental programme were compared with theoretical predictions. Based on the results of the experimental programme, it can be concluded that the addition of steel, polypropylene and hybrid fibers by 4% by weight of cement (but 2.14 % by volume of cement) had the best effect on the stiffness and energy absorption capacity of the beams.
Behavior of High-Strength Fiber-Reinforced Concrete Beams under Cyclic Loading
ACI Structural Journal, 2002
This study investigated both the influence of longitudinal steel ratio and steel jiber length on high-strength concrete (HSC) beams' behavior under alternate cyclic bending. The evolution in both structural properties and cracking patterns was c?mpared with results from the monatonic bending test. To ~erve the mjl~e of jibers on deterioration of mechanical properties due to loadmg cycles, high-strength jiber-reinforced concrete (HSFR.C) bemn:' were tested using two jiber.lengths: 30 and 60 mm. Th1s analysis highlighted the positive effect of jibers on both the secant structural stiffness and the cracking patterns during the prepealc stage. For the postpeak stage, the ductility measurement did not reveal an! improvement. In seismic cases, however. the .measure~ of cycl1c dissipated energy is an important parameter m evaluating structural behavior. Within this framework, the positive effect of fibers ?n energy dissipation as well as on the cumulative damage capac1ty has been underscored.
COMPARATIVE ANALYSIS OF BEAMS BECAUSE OF SEISMIC LOADS FOR DIFFERENT MATERIALS
IAEME PUBLICATION, 2021
Beams are the most important members of any civil structures because they bear the loads which act on the structure and hence provide a safe and secure closed area for the human beings to live. Because of this ever-increasing importance of the beams, researchers have studied a lot about the beams in order to enhance their properties. One such effort has been made in the current paper to analyse the beams for different materials. One G+4 building structure has been considered here for the analysis which will be tested and validated for seismic loads. Two load combinations have been used and the beams have been analysed for maximum relative displacement, maximum positive moment, maximum negative moment and maximum positive shear force for four outer beams which are supposed to be affected the most because of seismic loading. Cross-section of the beams will remain the same and for the current analysis rectangular cross-section of 0.23 m x 0.3 m has been selected.
Flexural Behaviour of Normal Strength and High Strength Fibre Concrete Beams
The paper presents the results of an experimental work on the flexural behaviour of two types of concrete in terms of the progressive cracking process until failure and the crack opening, and beam deflection, using Digital Image Correlation (DIC) technique. At serviceability limit states, comparisons of the building code equations and the equations developed by some researchers for the short-term deflections and crack widths have been made using the reinforced concrete test beams. The experimental results show that the addition of steel fibres increases the first cracking load and amplify the number of cracks which conducts to a remarkable decreasing in the crack width with an increasing in ductility. This study also shows that there is a good agreement between the deflection values for RC beams predicted by the major codes (Eurocode2, ACI 318 and the CAN/CSA-S806) and the experimental results for beams with steel fibres at service load. The most important added benefit of the DIC technique is that it allows detecting easily the first crack with a high precision, measures the crack opening and follows the progressive cracking process until failure of reinforced concrete members.