Papers by Keyword: Reinforced Concrete Beam

Abstract: This paper presents the relationship between crack width and acoustic emission (AE) energy in reinforced concrete (RC) beams subjected to cyclic loading. Two types of RC beams were tested, each reinforced with different tensile bar diameters: 12 mm (Y12) and 16 mm (Y16). The average ultimate loads (P_ult) for beams with Y12 and Y16 were 31 kN and 51 kN respectively. Beams tested under cyclic loading using Y12 and Y16 were labelled FT12 and FT16. Cyclic loading was applied at 80% of the P_ult and tests were continued until failure. A three-point bending test was performed under a sinusoidal load frequency of 1 Hz. AE monitoring was performed with six sensors installed at selected locations on the beams. The results showed that the crack width increased with the number of cycles, with correlation coefficients (R²) of 0.95 for FT12 and 0.93 for FT16, indicating a stronger linear relationship for both beams. Based on the trends in AE energy and crack width, three crack propagation stages were identified, with high AE energy found in both the initial microcrack formation and the final unstable failure stage. The results confirm that AE is an effective tool for early damage detection and fatigue monitoring in RC structures.

Abstract: This study investigates the relationship between compressive strength and mid-span deflection of reinforced concrete beams, as determined through experimental tests and numerical modelling. Six commonly used concrete classes in Morocco (C10, C15, C20, C25, C30, C35) were prepared and tested to evaluate their mechanical performance. The obtained compressive strength values were incorporated into numerical models created using Robot Structural Analysis software, enabling the simulation of beam behaviour under uniform distributed load. Experimental results confirm that the compressive strength values comply with Moroccan standard NM 10.1.051, and they are strongly influenced by the paste volume and the water–cement (w/c) ratio. Moreover, the presence of superplasticizer helps to maintain workability by prolonging the slump. The findings indicate that mid-span deflection increases with compressive strength, highlighting the close connection between material properties and structural response. This approach demonstrates the value of combining laboratory experimentation with numerical modelling to bridge the gap between academic practice and real-world applications in civil engineering.

Abstract: In this article unlike existing linear models, a nonlinear differential model is used to describe the nonlinear heat distribution in a reinforced concrete beam using a heating wire. The results of experiments carried out under different heating modes are adequately described with good approximation by the analytical results obtained using the methods of group analysis of differential equations.

Abstract: In the course of operation or armed hostilities the span r.c. structures are subject to substantial damage and considerable reduction of their bearing capacity, especially under low-cycle repeated loading. In this connection it becomes necessary to renew their operation capacity and/or improve their bearing capacity. However, the current design standards contain no recommendations as to determination of the residual bearing capacity of such structures and calculation of their reinforcement. There are methods of the operation capacity renewal and reinforcement of the structures by increasing their sections adding metal or reinforced concrete elements. Still, the calculation methods of such reinforcement are also imperfect. It is proposed to renew operation capacity of such structures by strengthening their tensioned parts with CFRP; the performed experimental research will provide the basis for calculating bearing capacity of said structures with the aid of the deformation method improved by the authors.

Abstract: The paper considers the results of the experimental study of the reinforced concrete beams strengthened by carbon fiber reinforced plastics (the CFRP). Eight reinforced concrete beams of the 80x160 mm section and 1500 mm designed span have been manufactured and tested. The influence of the number of the CFRP layers (strengthening power) on bearing capacity and rigidity under the static loading of beams in the thirds of the span has been studied. The results obtained indicate the increase in bearing capacity of the reinforced beams from 24% up to 55% and the increase in rigidity by 45% for the commonly adopted limiting state, i.e. achieving ultimate deformations in concrete of the compressed zone). The paper underlines the need for using anchor devices in the form of U-shaped binders to ensure the efficiency of the given method of strengthening.

Abstract: Non-destructive testing is a process of inspecting, testing, and evaluating materials, components or assemblies for discontinuities, or differences in characteristics without destroying the serviceability of a system or its part. The acoustic non-destructive methods are concerned with the state-of-the-art situation in the field of experimental studies of the physical properties of engineering materials. In this paper, the acoustic emission method was used for classification of cracks recorded during the cyclic loading of the reinforced concrete beam. Acoustic emission is a phenomenon of stress wave radiation caused by the dynamic reconstruction of material’s structure that accompanies processes of deformation and fracture. Crack propagation is one of the macroscopic sources of acoustic emission. Acoustic emission signals generated by different loading patterns can provide valuable information concerning the structural integrity of a material. Load levels that have been previously exerted on a material do not produce acoustic emission activity.

Abstract: Lightning protection system protects building structure from direct lightning impact. Embedding lightning protection cable inside concrete structure is widely use in practice now days. The objective of this research is to investigate the effect of installation of additional conductor cable inside concrete beam to its beam displacement and beam stress using finite element analysis software ABAQUS. The beam without additional conductor cable, with cable conductor installed at top and bottom reinforcement is modelled using ABAQUS. The results obtained from the three model is compared. As the result, the beam with additional conductor cable at top reinforcement shows minimum deformation and minimum Mises stress.

Abstract: There are a lot of concerns on safety structure performance by being buildings to be large and high-rise. In particular, damage due to the fire recently leads to a large disaster and therefore a variety of countries operate the regulation on the fire resistance performance depending on the building structure. There are differences on the fire resistance design in each country but 50% of the design load is suggested to be reasonable for the normal temperature during the fire by applying the concept of the loading ratio to the fire resistance design of structures. Since the loading ratio is the factor having a major impact on the evaluation of the fire resistance performance, it should be preferentially considered. The study on setting up the loading ratio to evaluate the fire resistance performance and safety of structures has yet to be fully furnished in South Korea. Therefore, in this paper, the loading ratio proper for the construction status in South Korea is to be taken into account and then the ratio is to be proposed on the single reinforcement beam.

Abstract: Based on the fatigue damage mechanism, fatigue life, stiffness degradation, crack width change, bending, shear fatigue properties and other aspects, this paper introduces the research progress of the fatigue properties of ordinary reinforced concrete beams. And the existing reinforced concrete beam flexural, shear fatigue properties of research ideas, methods and results are summarized, providing the basis for further study on the fatigue performance of reinforced concrete beams. At present, the research results show that the fatigue damage of reinforced concrete beam is basically in accordance with the law of the three stages. In the early stage of fatigue, the tensile concrete cracks and exits, and the damage develops rapidly. In the middle of fatigue crack growth, fatigue damage is developed into a more moderate linear growth. In the late stage of fatigue, fatigue fracture occurs in the steel bar, and the bearing capacity of the beam is quickly lost.

Abstract: The limited lengths of reinforcing bars have been commonly found in the practical construction of most reinforced concrete structures. The required length of a bar may be longer than the available stock of steel length. For maintaining desired continuity of the reinforcement in almost all reinforced concrete structures, some reinforcing bars should be carefully spliced. In the case of long flexural beam, bar installers end up with two or even more pieces of steel that must be spliced together to accomplish the desired steel length. An experimental study was conducted to investigate flexural behavior of reinforced concrete beams utilizing a variety lap splices of reinforcing steel bars under two-point loading. Five variations of lap splices of reinforcing steel bars positioned at midspan of tensile reinforcement of the beam were investigated. Welded joints and overlapped splices were used to construct the variation of lap splices of reinforcing steel bars. The general trend in crack pattern, the load deflection characteristics and the mode of failure of flexural beams under two-point loading were also observed. The flexural strength comprising load-displacement response, flexural crack propagation, displacement ductility is briefly discussed in this paper.