• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.261-268
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• 1999

The seismic performance of precast concrete panel structures tested previously has been evaluated in this paper. Hysteretic curves of test specimens are idealized to elasto-plastic curves to get reliable yielding and ultimate displacements. For the idealized curves, ductility and energy dissipation capacity of specimens have been evaluated using a few guide lines. In addition, the strength capacity of specimens is checked for the strength demand caused by the design earthquake load including overturning moment effects. The result shows while the strength of specimen with joint box for vertical continuity is little bit lower than that of specimen connected by welding, the ductility of the former is higher than that of the latter. The energy dissipation ratios of PC specimens are ranged from 83% to 96% of that of Re specimen and the average of those are shown 90%.

• Advances in concrete construction
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• v.1 no.3
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• pp.215-225
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• 2013

The results of experimental testing of the effect of confined concrete on compressive strength and ductility of concrete beam subjected to pure bending are presented. The effect of different stirrups forms and spacing, as well as different concrete strengths, on beam carrying capacity and ductility were analyzed. Ultimate strength capacity and deflection of concrete beam increase with the decrease in stirrups spacing. Stirrup form has a great effect on the ultimate carrying capacity and ductility of concrete beam. Stirrups which confined the region of concrete in the compression more contribute to greater compression strength of concrete than common stirrups at the perimeter of the entire cross-section of the beam.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.501-506
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• 1998

This paper is an experimental study on the flexural strength and ductility capacity of reinforced high performance concrete beams with the concrete which has compressive strength of 600~700kg/$\textrm{cm}^2$, slump value of 20~25cm and slump-flow value of 60~70cm. Total 8 beams with different tensile reinforcement ratio and pattern of loading were tested. Form the results of reinforced high performance concrete beams, the equivalent stress block parameters proposed by MacGregor et al. or New Zealand code are recommended to use. Also, an extreme fiber concrete compressive strain of reinforced high performance concrete beams are distributed 0.0033~0.0048. In reinforced high performance concrete beams, reinforcement ratio in order to insure curvature ductility index 2 and 4 propose by ACI code should be less than those of reinforced normal strength concrete beams.

• Structural Engineering and Mechanics
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• v.58 no.2
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• pp.379-395
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• 2016

A seismic strengthening method using Velcro is proposed to improve the seismic performance of columns in RC frame structures. The proposed method was evaluated experimentally using three fabricated RC specimens. Velcro was wrapped around the columns of the RC-frame specimen to prevent concrete spall falling. The reinforcing performance of the Velcro was determined from comparison of results on seismic performance (i.e., strength, displacement, failure mode, displacement ductility capacity and amount of dissipated energy). As the displacement of the reinforced specimens was increased, the amount of dissipated energy increased drastically, and the displacement-ductility-capacity of the reinforced specimens also increased. The final failure mode of RC frame structure was changed. As a result, it was concluded that the proposed seismic strengthening method using Velcro could be used to increase the displacement ductility of RC columns, and could be used to change the final failure mode of RC-frame structures.

• Steel and Composite Structures
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• v.17 no.4
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• pp.517-533
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• 2014

Experimental results of 39 specimens including concrete columns, RC columns, hollow steel tube columns, concrete filled steel tubular (CFT) columns, and reinforced concrete filled steel tubular (RCFT) columns are presented. Based on the experimental results, the load-carrying capacity, confined effect, ductility, and failure mode of test columns are investigated. The effects of the main factors such as width-thickness ratio (the ratio of external diameter and wall thickness for steel tubes), concrete strength, steel tube with or without rib, and arrangement of reinforcing bars on the mechanical characteristics of columns are discussed as well. The differences between CFT and RCFT are compared. As a result, it is thought that strength, rigidity and ductility of RCFT are improved; especially strength and ductility are improved after the peak of load-displacement curve.

• Earthquakes and Structures
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• v.11 no.4
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• pp.665-680
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• 2016

This paper focuses on the study of seismic behavior of steel reinforced concrete special-shaped column-beam joints. Six specimens, which are designed according to the principle of strong-member and weak-joint core, are tested under low cyclic reversed load. Key parameters include the steel form in column section and the ratio of column limb height to thickness. The failure mode, load-displacement curves, ductility, stiffness degradations, energy dissipation capacity and shear deformation of joint core of the test subassemblies are analyzed. The results indicate that SRC special-shaped column-beam joints have good seismic behavior. All specimens failed due to the shear failure of the joint core, and the failure degree between the two sides of joint core is similar for the exterior joint but different for the corner joint. Compared to the joints with channel steel truss, the joints with solid web steel skeleton illustrate better ductility and energy dissipation capacity, but the loading capacity and stiffness are roughly close. With the increasing of the ratio of column limb height to thickness, the joints illustrate higher loading capacity and stiffness, better energy dissipation capacity, but worse ductility.

• Steel and Composite Structures
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• v.37 no.5
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• pp.503-516
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• 2020

A novel spiral confined angle-steel reinforced concrete (SCARC) column was developed in this study. A total of 16 specimens were prepared and tested (eight of them were tested under axial loading, the other eight were tested under eccentric loading). The failure processes and load-displacement relationships of specimens under axial and eccentric loads were examined, respectively. The load-carrying capacity and ductility were evaluated by parametric analysis. A calculation approach was developed to predict the axial and eccentric load-carrying capacity of these novel columns. Results showed that the spiral reinforcement provided enough confinement in SCARC columns under axial and low eccentric loads, but was not effective in that under high eccentric loads. The axial load-carrying capacity and ductility of SCARC columns were improved significantly due to the satisfactory confinement from spirals. The outer reinforcement and other construction measures were necessary for SCARC columns to prevent premature spalling of the concrete cover. The proposed calculation approach provided a reliable prediction of the load-carrying capacity of SCARC columns.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.8
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• pp.3-11
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• 2018

In this study, total nine R/C beams, designed by the PVA Fiber with ground granulated blast furnace slag and recycled fine aggregate were constructed and tested under monotonic loading. In the material development, micromechanics was adopted to properly select the optimized range of the composite based on steady-state cracking theory and experimental studies on the matrix and interracial properties. Experimental programs were carried out to improve and evaluate the structural performance of the test specimens: the load-displacement, the failure mode, the maximum strength, and ductility capacity were assessed. Test results showed that test specimens (BSPR-20, 40) was increased the maximum load carrying capacity by 3~6% and the ductility capacity by 9~14% in comparison with the standard specimen (BSS). And the specimens (BSPR-60, 80, 100) was decreased the maximum load carrying capacity by 0~4% and the ductility capacity by 79% in comparison with the standard specimen (BSS) respectively.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.103-111
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• 2007

Experimental study was carried out to investigate the structural performance of composite beams with steel fiber concrete and angle. For this purpose, seven specimens composed of two RC beams with or without steel fiber and five composite beams with steel fiber and angle were constructed and tested. All specimens had no web shear reinforcement. Main variables for the specimens were tensile reinforcement ratio and fiber volume fraction. Based on the test results, structural performance such as strength, stiffness, ductility and energy dissipation capacity was evaluated and compared with the predicted strength. The prediction of flexure and shear strength gives a good relationship with the observed strength. The strength, ductility and energy dissipation capacity are increased, as the fiber volume fraction is increased. Meanwhile, high tensile reinforcement ratio resulted in the reduction of ductility and energy dissipation capacity for the composite beams.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.113-120
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• 2005

The purpose of this study is to investigate the strength and ductility improvement of columns retrofitted by steel-fiber composite plate. Test specimens strengthened by three different materials - steel plate(SP), carbon fiber sheet(CF) and fiber-steel composite plate(CP) - were tested under cyclic lateral load with a constant axial load equal to $20\%$ of the axial compression capacity. The structural capacity of composite plate was good or better than that of other retrofitting materials. Test results from all retrofitted specimens showed that considerably higher retrofitting amount was required for strength enhancement. The ductility of retrofitted columns by composite plate was fairly improved. Also, energy ductility ratio was more effective than displacement ductility ratio for ductility estimation of retrofitted column.