IJERT-Experimental and Analytical Study on High Strength Concrete Beams under Flexure (original) (raw)
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4th International Conference on Advances in Civil Engineering, 2018
The use of high strength concrete has become popular in construction work because of its improved strength and durability. High-strength concrete can be used as a substituting material over conventional concrete for structural members. This study describes the flexural behaviour of high strength reinforced concrete beam. The variation of flexural ductility with concrete compressive strength is quite complicated and thus sincerely reviewed in this paper. An experimental and numerical investigation of high strength reinforced concrete beam has been conducted in the present study. Four simply supported beams, having compressive strength of 27.50 MPa, 43.85 MPa, 54.05 MPa and 62.01 MPa, reinforced in top and bottom edges of the beam have been investigated in this study. The beams were tested under two-point loading to reveal their flexural behaviour. Load-deflection diagram and ductility index are the primary parameters that were considered in this study. The ultimate loads that obtained from the experimental results were found to be in good agreement with the numerical results. In addition, this study also compared the theoretical and experimental deflection at the mid-point of the beam. The cracking behaviour of all the beams and the crack width is also reviewed in this paper.
Nominal flexural strength of high-strength concrete beams
Advances in concrete construction, 2019
The conventional ACI rectangular stress block is developed on the basis of normal-strength concrete column tests and it is still being used for the design of high-strength concrete members. Many research papers found in the literature indicate that the nominal strength of high-strength concrete members appears to be over-predicted by the ACI rectangular stress block. This is especially true for HSC columns. The general shape of the stress-strain curve of high-strength concrete becomes more likely as a triangle. A triangular stress block is, therefore, introduced in this paper. The proposed stress block is verified using a database which consists of 52 tested singly reinforced high-strength concrete beams having concrete strength above 55 MPa (8,000 psi). In addition, the proposed model is compared with models of various design codes and proposals of researchers found in the literature. The nominal flexural strengths computed using the proposed stress block are in a good agreement with the tested data as well as with that obtained from design codes models and proposals of researchers.
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.
In order to evaluate whether high strength concrete with recycled aggregate can be applied for concrete structures, flexural loading tests of reinforced recycled concrete members are to be carried out. The results of this test programme to study the use of recycled coarse aggregate in high strength 40 N/mm 2 concrete are to be described. The recycled coarse aggregates are mainly produced from various concrete members of a building structure. The high strength concrete by using different percentage of recycled aggregates is testing in this project. Also finite element modelling and analysis of beams are also going to be performed. The aim for this ongoing project is to determine the flexural strength characteristic of recycled aggregates for application in high strength structural concrete, which will give a better understanding on the properties of concrete with recycled aggregates, as an alternative material to coarse aggregate in structural concrete.
Flexural Behaviour of Reinforced High Performance Concrete Beams Subjected to Bending
This paper presents the findings of the comprehensive experimental investigation on the use of industrial by-products like silica fume, bottom ash and steel slag aggregate for making reinforced high performance concrete beams for enhancing the flexural strength. Based on the encouraging results of the preliminary experimental work conducted by the authors, a comprehensive experimental investigation was carried out by testing ten numbers of RC beams with varying mix ratio of industrial by-products in order to further explore the viability of this technique. Data presented include the parameters such as load-deflection behaviour, moment-curvature relationship, ductility and energy absorption capacity. A reinforced high performance concrete beam proves to be effective at controlling cracks and exhibits ductility with a ductility ratio. The investigation revealed that the flexural behaviour of reinforced high performance concrete beams was comparable to that of control beams. The results of this study provide valuable data that can be used in further studies on the development of computational models of the deflection and flexural of HPC.
Engineering properties and structural behaviour of high strength reinforced concrete beams
1997
High Strength Concrete (HSC) has become a viable alternative to lower strength concrete. However, its utilisation is increasing faster than the development of suitable design recommendations. This is because limited and diverse investigations have been carried out concerning engineering properties and structural behaviour of HSC. The experimental investigation and theoretical considerations described in this thesis have been undertaken as an attempt to start to remedy this problem. As part of the investigation into the structural behaviour of HSC beams, a series of 18 different concrete mixes were tested in order to optimise HSC mixes using local aggregates. The effect o f different factors such as w/c ratios, silica fume and superplasticizer dosages on compressive strength and splitting tensile strengths in the range of 80 to 120 N/mm2 (MPa) were studied. Additionally, new mathematical expressions were developed to replace some of the currently used relationships concerning HSC as ...
Effect of loading rate on flexural behavior of concrete and reinforced concrete beams
Journal of Science and Technology in Civil Engineering (STCE) - NUCE, 2021
The elasto-plastic characteristics of plain concrete are inevitably affected by the loading rate. This paper presents an experimental investigation on the effect of loading rate on flexural behavior of concrete and reinforced concrete (RC) beams, which was carried out with Walter+bai electro-hydraulic servo system. Three-point bending tests on 100 × 100 × 400 mm prismatic concrete samples and 80 × 120 × 1100 mm RC beams with different displacement controlled loading rates of 0.01 mm/min, 0.1 mm/min, and 3 mm/min were imposed. Based on the test results, the effects of loading rates on the load-displacement curve, cracking, and ultimate load-carrying capacities of RC beams were evaluated.
In the current study, nineteen reinforced concrete beams were tested to investigate the static shear behavior of high strength concrete beams as compared with normal strength concrete beams. The concrete compressive strength of the beams at the age of the tests ranged from 300 to 800 kg/cm 2. The parameters of the study included the concrete strength, shear span to depth ratio a/d, the amount of shear reinforcement (stirrup spacing S) and the inclination of the stirrups with the horizontal axis of the beam. The details of the beam specimens, material properties, instrumentation and the testing procedure are described in this paper. The test results are presented and discussed, and the influence of each design parameter is investigated. Furthermore, parametric analysis was carried out to deduce equations for predicting the cracking and ultimate shear strength and the ratio between them for both normal and high strength concrete beams. Test results are also compared with different existing approaches.
Nuclear Engineering and Design, 2011
The present work is an attempt to study the neutral axis variation and the evolution of the moment inertia with the loading of over reinforced high strength concrete sections in conjunction with ACI 318-05. In this sense, four high strength concrete beams, having different tension reinforcement quantities expressed as proportions of the balanced steel ratio (0.75ρ b, 0.85ρ b, ρ b, 1.2ρ b) were tested. Measurements of the deflection and the reinforcement and concrete strains of all specimens were made during the loading process. The load-neutral axis depth variation and the load-section stiffness curves were drawn. The slope of the line connecting the origin of the first crack to the initial yielding of the failure point in the neutral axis depth-load graphs shows the rate of ductility; ductile behaviour in the beam increases as the slope becomes steeper. Based on the results of this study, it is recommended that the modulus of elasticity of concrete E c be reviewed and evaluated at a stress higher than 0.5 f′ c for the determination of the cracked moment of inertia.