• Advances in concrete construction
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• v.13 no.3
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• pp.243-254
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• 2022

Reinforced concrete (RC) deep beams are critical structural elements used in offshore pile caps, rectangular cross-section water tanks, silo structures, transfer beams in high-rise buildings, and bent caps. As a result of the low shear span ratio to effective depth (a/d) in deep beams, arch action occurs, which leads to shear failure. Several studies have been carried out to improve the shear resistance of RC deep beams and avoid brittle fracture behavior in recent years. This study was performed to investigate the behavior of RC deep beams numerically and experimentally with different reinforcement arrangements. Deep beams with four different reinforcement arrangements were produced and tested under monotonic static loading in the study's scope. The horizontal and vertical shear reinforcement members were changed in the test specimens to obtain the effects of different reinforcement arrangements. However, the rebars used for tension and the vertical shear reinforcement ratio were constant. In addition, the behavior of each deep beam was obtained numerically with commercial finite element analysis (FEA) software ABAQUS, and the findings were compared with the experimental results. The results showed that the reinforcements placed diagonally significantly increased the load-carrying and energy absorption capacities of RC deep beams. Moreover, an apparent plastic plateau was seen in the load-displacement curves of these test specimens in question (DE-2 and DE-3). This finding also indicated that diagonally located reinforcements improve displacement ductility. Also, the numerical results showed that the FEM method could be used to accurately predict RC deep beams'behavior with different reinforcement arrangements.

• Journal of Korean Association for Spatial Structures
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• v.5 no.4 s.18
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• pp.71-77
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• 2005

Bonded CFRP Plate method used murk in reinforcement method is very efficient for stress increment of reinforced members. But CFRP plate dosen't display enough its capacity and have the destruction characteristic of premature failure that reach failure by debond plate, because near-surface-bond using epoxy. Such destruction character of reinforced specimens take the influence at variables as steel reinforcement ratio, concrete strength, kind of reinforcement materials, reinforced length, property of epoxy used in binder and so on. In this study, performed experiment results are compared and considered on flexural performance of Near Surface Mounted Reinforcement used CFRP-Rod, as complement about structural behavior of RC beam reinforced flexural capacity in CFRP plate and premature failure of reinforcement material. Main variables of RC beam applied CFRP Plate external bond method are experimental variables as reinforcement length, reinforcement position (tension face and side face of beam) and existence of ironware in end parts. In case of CFRP-Rod, variable is reinforcement length.

• Smart Structures and Systems
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• v.5 no.4
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• pp.443-455
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• 2009

The use of fiber reinforced polymer (FRP) reinforcement in concrete structures has been on the rise due to its advantages over conventional steel reinforcement such as corrosion. Reinforcing steel corrosion has been the primary cause of deterioration of reinforced concrete (RC) structures, resulting in tremendous annual repair costs. One application of FRP reinforcement to be further explored is its use in RC frames. Nonetheless, due to FRP's inherently elastic behavior, FRP-reinforced (FRP-RC) members exhibit low ductility and energy dissipation as well as different damage mechanisms. Furthermore, current design standards for FRP-RC structures do not address seismic design in which the beam-column joint is a key issue. During an earthquake, the safety of beam-column joints is essential to the whole structure integrity. Thus, research is needed to gain better understanding of the behavior of FRP-RC structures and their damage mechanisms under seismic loading. In this study, two full-scale beam-column joint specimens reinforced with steel and GFRP configurations were tested under quasi-static loading. The control steel-reinforced specimen was detailed according to current design code provisions. The GFRP-RC specimen was detailed in a similar scheme. The damage in the two specimens is characterized to compare their performance under simulated seismic loading.

• Journal of Korean Association for Spatial Structures
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• v.5 no.3 s.17
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• pp.109-115
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• 2005

The experimental work was performed to investigate the effect influenced to the hystresis and the flexural strength improvement of RC beam using carbon fiber plates. Major parameters of this experimental program were the section size of carbon fiber plates and the damage level of RC beam before reinforcement. Particularly, the damage level of beam is for the cases damaged by overloads. The damage level is for 30%, 60%, and 100% of flexural strength, and no damaged beams were also tested for comparison with the damaged one. from the test results, it showed that the beams reinforced by carbon fiber plates had the higher strength and lower deformation capacity than the general beams and that it had the same ductility ratio of the general beams.

• Structural Engineering and Mechanics
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• v.88 no.6
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• pp.599-608
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• 2023

The present study is focused on instigation of the nonlinear mechanical behavior of reinforced concrete beams considering different types of FRP bars through nonlinear finite element simulations. To explore the impact of the FRP reinforcement type and geometry on the nonlinear mechanical behavior of reinforced beam, intensive parametric studies are carried out and discussed. Twenty models were carried out based on the finite element software (ABAQUS). The concrete damage plasticity model was considered. Four types of fiber polymer bars, CFRP, GFRP, AFRP and BFRP as longitudinal reinforcement for concrete beam were used. The validation of numerical results was confirmed by experimental as well as numerical results, then the parametric study was conducted to evaluate the effect of change in different parameters, such as bar diameter size, type of FRP bars and shear span length. All results were analyzed and discussed through, load-deflection diagram. The results showed that the use of FRP bars in rebar concrete beam improves the beam stiffness and enhance the ultimate load capacity. The load capacity enhanced in the range of (20.44-244.47%) when using different types of FRP bars. The load-carrying capacity of beams reinforced with CFRP is the highest one, beams reinforced with AFRP is higher than that reinforced with BFRP but beams reinforced with GFRP recorded the lowest load of capacity compered with other beams reinforced with FRP Bars.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.691-698
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• 2001

Recent trends in the construction of long span or tall building frames feature the increase use of composite members that steel and concrete is functioning together in what terms of mixed structural systems. One of such systems, RCS (reinforced concrete column and steel beam) system is introduced and closely examined focusing on bearing strength of the composite joint in this paper. The main objective of this study was to develope detail to increase bearing capacity while bearing failure is one of the two primary modes of failure in RCS system. The results show that specimens with the U-type bearing reinforcement detail developed in this study enhanced the bearing strength by 1.20-1.50. The U-type reinforcement is the effective details to increase joint bearing strength compared to others like vertical reinforcement welded to beam flanges.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.6
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• pp.361-368
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• 2016

Coupling beams serve as primary source of energy dissipation in coupled shear wall systems during large earthquakes. However, the overestimation of the shear strength of diagonally reinforced coupling beams may be adverse effect on the seismic performance of coupled shear wall systems. In order to force coupling beams to properly work during earthquakes, coupling beams should be designed with accurate shear strength equations. The objective of this study is to propose the accurate shear strength equation for slender diagonally reinforced coupling beams. For this purpose, experimental tests were conducted using three diagonally reinforced coupling specimens with different amount of transverse reinforcement under reversed cyclic loads to evaluate the hysteretic behavior of the specimens. The test results show that transverse reinforcement of slender diagonally reinforced coupling beam affects the maximum strength and drift ratio.

• Computers and Concrete
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• v.11 no.5
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• pp.399-410
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• 2013

A nonlinear finite element analysis of R/C hybrid deep T-beam with web opening subjected to pure torsion is presented. Hexahedral 8-nodes and space truss element were used for modeling concrete and reinforcement. The reinforcement was assumed perfectly bonded to the corresponding nodes of the concrete element. The constitutive relations for concrete and reinforcement are based on the modified field theory and elastic perfectly plastic. The smear crack approach was adopted for modeling the crack. The torque-twist angle relationship curve based on the finite element analysis was compared to the experimental results. The comparison shows that the curve of torque-twist angle predicted by the nonlinear finite element analysis is linear before cracking and close to the experimental result. After cracking, the curve becomes nonlinear and stiffer compared to the experimental result.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.667-674
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• 2015

In this paper, shear behavior of concrete wide beam reinforced with plates with openings was evaluated. For this evaluation, evelen specimens were manufactured. One specimen was non-shear reinforced, five specimens were reinforced with steel plates and the other five specimens were reinforced GFRP plates. Shear strengths measured through experiments were compared with ones calculated from the equation provided by ACI 318. Longitudinal spacing of shear reinforcement, transverse spacing of shear reinforcement and shear reinforcement material were considered as variables. Test results showed that the shear strength increased as the transverse and longitudinal spacing of shear reinforcement became narrow. Also, regardless of material type of shear reinforcement, the shear capacity was similar when the amount of shear reinforcement was the same.

• Structural Engineering and Mechanics
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• v.84 no.4
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• pp.547-560
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• 2022

By presetting various reinforcement diameters in topology optimization with the discrete model finite element analysis, an algorithm of bidirectional evolutionary structural optimization of multi-level reinforcement diameter is presented to obtain the optimal reinforcement topologies which describe the degree of stress of different parts. The results of a comparative study on different reinforcement feasible domain demonstrate that the more angle types of reinforcement are arranged in the initial domain, the higher utilization rate of reinforcement of the optimal topology becomes. According to the nonlinear finite element analysis of some deep beam examples, the ones designed with the optimization results have a certain advantage in ultimate bearing capacity, although their failure modes are greatly affected by the reinforcement feasible domain. Furthermore, the bearing capacity can be improved when constructional reinforcements are added in the subsequent design. However the adding would change the relative magnitude of the bearing capacity between the normal and inclined section, or the relative magnitude between the flexural and shear capacity within the inclined section, which affects the failure modes of components. Meanwhile, the adding would reduce the deformation capacity of the components as well. It is suggested that the inclined reinforcement and the constructional reinforcement should be added properly to ensure a desired ductile failure mode for components.