• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.763-768
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• 2000

The purpose of this paper is to predict the flexural strengthening of reinforced concrete beams by the external bonding of carbon fiber reinforced plate(CFRP) to the tension face of the beam. Used computational equation is derived by relation of stress an strain. This equation is applied to four-nondamage beam and tow-preloading beam. Six scale beams were tested to evaluate the strength enhancement provided by the CFRP. And describes the strength enhancement provided to the flexural capacity of reinforced concrete beam by the external bonding of CFRP. An inelastic section analysis procedure was developed that accurately predicts the load displacement response of the retrofitted beams.

• Structural Engineering and Mechanics
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• v.6 no.2
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• pp.161-172
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• 1998

Reinforced concrete beams possess variable flexural and torsional stiffnesses due to formation of cracks in the tension area along the beam. In order to check the stability of the beam, it is thus more appropriate to divide the beam into a finite number of segments for which mean stiffnesses and also bending moments are calculated. The stability analysis is further simplified, by using these mean values for each segment. In this paper, an algorithm for calculating the critical lateral buckling slenderness ratio for a definite load level, in a reinforced concrete beam without lateral support at the flanges, is presented. By using this ratio, the lateral buckling safety level of a slender beam may be checked or estimated.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.12
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• pp.35-40
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• 2018

In this study, experimental research was carried out to evaluate the seismic performance of reinforced concrete exterior beam-column joint regions using hybrid retrofitting with AFRP sheets and embedded CFRP reinforcements in existing reinforced concrete building. Therefore it was constructed and tested three specimens retrofitting the beam-column joint regions using such retrofitting materials. Specimens, designed by retrofitting the beam-column joint regions of existing reinforced concrete structure, were showed the stable failure mode and increase of load-carrying capacity due to the effect of crack control at the times of initial loading and confinement of retrofitting materials during testing. Specimens RBCJ-SRA3 designed by the retrofitting of AFRP sheets and embedded CFRP reinforcements in reinforced exterior beam-column joint regions were increased its maximum load carrying capacity by 1.86 times and its energy dissipation capacity by 1.65 times in comparison with standard specimen RBCJ for a displacement ductility of 5.

• Steel and Composite Structures
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• v.9 no.2
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• pp.159-172
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• 2009

Two prestressed steel reinforced high performance concrete (SRC) beams, a nonprestressed SRC beam and a counterpart prestressed concrete beam were tested under low reversed cyclic loading to evaluate seismic performance of prestressed SRC beams. The failure modes, deformation restoring capacity, ductility and energy dissipation capacity of the prestressed SRC beams were discussed. Results showed that due to the effect of plastic deformations of steel beams encased in concrete, the three SRC beams exhibited residual deformation ratios ranging between 0.64 and 0.79, which were apparently higher than that of the prestressed concrete beam (0.33). The ductility coefficients of the prestressed SRC beams and the prestressed concrete beam ranged between 4.65 and 4.87, obviously lower than that of nonprestressed SRC beam (9.09), which indicated the steel beams influenced the ductility little while prestressing resulted in an apparent reduction in ductility. The amount of energy dissipated by the prestressed SRC beams was less than that dissipated by the nonprestressed SRC beam but much more than that dissipated by the prestressed concrete beam.

• Computers and Concrete
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• v.18 no.3
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• pp.405-420
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• 2016

Recently laser scanning technologies become widely used in many areas of the modern economy. In the following paper authors show a potential spectrum of use Terrestrial Laser Scanning (TLS) in diagnostics of reinforced concrete elements. Based on modes of failure analysis of reinforcement concrete beam authors describe downsides and advantages of adaptation of terrestrial laser scanning to this purpose, moreover reveal under which condition this technology might be used. Research studies were conducted by Faculty of Civil and Environmental Engineering at Gdansk University of Technology. An experiment involved bending of reinforced concrete beam, the process was registered by the terrestrial laser scanner. Reinforced concrete beam was deliberately overloaded and eventually failed by shear. Whole failure process was tracing and recording by scanner Leica ScanStation C10 and verified by synchronous photographic registration supported by digital photogrammetry methods. Obtained data were post-processed in Leica Cyclone (dedicated software) and MeshLab (program on GPL license). The main goal of this paper is to prove the effectiveness of TLS in diagnostics of reinforced concrete elements. Authors propose few methods and procedures to virtually reconstruct failure process, measure geometry and assess a condition of structure.

• Structural Engineering and Mechanics
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• v.24 no.3
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• pp.291-306
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• 2006

In order to improve the constructability and meanwhile ensure excellent seismic behavior, several innovative composite connection details were conceived and studied by the authors. This paper reports experimental results and observations on seismic behavior of steel beam bolted to reinforced concrete column connections (bolted RCS or BRCS). The proposed composite connection details involve post tensioning the end plates of the steel beams to the reinforced concrete or precast concrete columns using high-strength steel rods. A rational design procedure was proposed to assure a ductile behavior of the composite structure. Strut-and-tie model analysis indicates that a bolted composite connection has a favorable stress transfer mechanism. The excellent capacity and behavior were then validated through five full-scale beam to column connection model tests.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.579-584
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• 2001

A method is described for predicting crack with and spacing in Steel Fiber Reinforced Concrete (SFRC). The crack behavior of SFRC influenced by longitudinal reinforcement ratio, volume and type of steel fiber, strength of concrete. It can be observed from experimental results that addition of steel fiber to reinforced concrete beam reduces crack width in serviceability limit states. The proposed method predicts crack widths in cracking stage of the beam. Calculated crack widths obtained for reinforced concrete beams and different volume and type of steel fiber, strength of concrete showed good agreement with experimental results.

• Steel and Composite Structures
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• v.20 no.2
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• pp.337-355
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• 2016

Steel coupling beam in reinforced concrete (RC) coupled shear wall system is a proper substitute for deep concrete coupling beam. Previous studies have shown that RC coupled walls with steel or concrete coupling beam designed with strength-based design approach, may not guarantee a ductile behavior of a coupled shear wall system. Therefore, seismic performance evaluation of RC coupled shear wall with steel or concrete coupling beam designed based on a strength-based design approach is essential. In this paper first, buildings with 7, 14 and 21 stories containing RC coupled shear wall system with concrete and steel coupling beams were designed with strength-based design approach, then performance level of these buildings were evaluated under two spectrum; Design Basis Earthquake (DBE) and Maximum Considered Earthquake (MCE). The performance level of LS and CP of all buildings were satisfied under DBE and MCE respectively. In spite of the steel coupling beam, concrete coupling beam in RC coupled shear wall acts like a fuse under strong ground motion.

• Steel and Composite Structures
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• v.28 no.1
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• pp.83-98
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• 2018

This research was conducted to study the behavior of exterior concrete beam-column joints with reinforced shape memory alloy (SMA) bars tested under cyclic loading. These bars benefit from superelastic behavior and can stand high loads without residual strains. The experimental part of the study, 8 specimens of exterior concrete beam-column joints were made and tested. Two different types of concrete with 30 and 45 MPa were used. Four specimens contained SMA bars and 4 specimens contained steel bars in beam-column joints. Furthermore, different transverse reinforcements were used in beams investigate the effects of concrete confinement. Specimens were tested under cyclic loading. Results show that SMA bars are capable of recentering to their original shape after standing large displacements. Due to the superelastic behavior of SMA bars, cracks at the joint core vanish under cyclic loading. As the cyclic loading increased, bending failure occurred in the beam outside the joint core. In the analytical parts of the study, specimens were simulated using the SeismoStruct software. Experimental and analytical results showed a satisfactory correlation. Plastic hinge length at the beam joint for specimens with SMA and steel bars was calculated by empirical equations, experimental and analytical results. It was shown that Paulay's and Priestley's equations are appropriate for concrete beam-column joints in both types of bars.

• International Journal of Concrete Structures and Materials
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• v.18 no.3E
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• pp.199-205
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• 2006

The composite frame system with reinforced concrete column and steel beam can be improved in its structural efficiency by complementing the shortcomings of the two systems. The system, however, has many inherent problems in practical design and construction process due to the dissimilarities of the materials. Considering these circumstance, this research aims for the development of a composite structural system which connects the steel beams to the R/C columns with higher structural safety and economy. Basically, the proposed connection system is composed of four split tees, structural angles reinforced by a stiffener, high strength steel rods, connecting plates and shear plates. Structural tests have been carried out to investigate the moment transfer mechanism 1Tom the beam flange to steel rods or connecting plates through the structural angle reinforced by a stiffener. The four prototype specimens have been tested until the flange of the beam reached a plastic state. The test results indicated that no distinct material dissimilarities between concrete and steel have been detected for the proposed hybrid beam-column connection system and that the stress transfer through the structural angle between the beam flange and steel rods or connecting plates was very encouraging.