• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.3
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• pp.141-148
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• 2022

In this study, the structural behavior of reinforced concrete members under simultaneous axial and blast loads was analyzed. Nonlinear dynamic analysis verification was performed using the experimental data of panels under fundamental blast load as well as those of reinforced concrete columns subjected to axial and blast loads. Because Autodyn is a program designed only for dynamic analysis, an analysis process is devised to simulate the initial stress state of members under static loads, such as axial loads. A total of 80 nonlinear dynamic finite element analysis procedures were conducted by selecting parameters corresponding to axial load ratios and scaled distances ranging 0%~70% and 1.1~2.0 (depending on the equivalent of TNT), respectively. The structural behavior was compared and analyzed with the corresponding degree of damage and maximum lateral displacement through the changes in axial load ratio and scaled distance. The results show that the maximum lateral displacement decreases due to the increase in column stiffness under axial loads. In view of the foregoing, the formulated analysis process is anticipated to be used in developing blast-resistant design models where structural behavior can be classified into three areas considering axial load ratios of 10%~30%, 30%~50%, and more than 50%.

• Journal of Korean Society of Steel Construction
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• v.14 no.3
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• pp.463-470
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• 2002

The TEC-Beam system is a composite beam consisting of structural tee, precast concrete, and cast-in-site reinforced concrete slab. The preliminary test of the proposed system was performed for simple beams, showing good behavior. However, for the field application of the system. TEC-Beam - RC column connection was required to produce a mechanism that transfers the force occurring in the lower part of the TEC-Beam. Thus, this study developed a connection mechanism that transfers the force occurring in the lower part of the TEC-Beam. Thus, this study developed a connection wherein the section of the TEC-Beam was enlarged and the lower part reinforced. Two setups of the proposed system were experimentally investigated. using the anchorage length of reinforcement., i.e., length of the increased section, as test parameter. It could be concluded from the result that the proposed system shows good structural behavior, with potential applicability in the field.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.573-580
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• 2014

In this paper, axial strains and lateral displacements of columns in a 58-story reinforced concrete building were measured using vibrating wire gauge and laser scanner, respectively, and compared with predicted values. Predictions were obtained using ASAP, which is a 3D construction stage analysis program developed based on PCA report. Comparisons indicated that columns in the middle of floor plan showed good correlation with predictions. However, the columns in the corners showed some deviations. Lateral displacement of columns between measurement and estimation showed similar trends but considerable deviations, which are seemingly caused by construction error of column faces, and inaccuracy in differential vertical displacement prediction.

• Journal of the Korea Institute of Building Construction
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• v.5 no.4 s.18
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• pp.145-152
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• 2005

Long-term axial shortening of the vertical elements of tail buildings results in differential movements between two elements and may lead to the additional moments of connection beam and slab elements, and other secondary effects, such as cracks of partitions or curtain walls. Accurate prediction of time-dependent column shortening is essential for tall buildings from both strength and serviceability aspects. The compensation method is different from reinforced concrete and SRC(Steel Reinforced Concrete) members. The SRC columns are usually compensated according to total differential shortening between two vertical elements. In this study, column shortenings of 37-story W building under construction are predicted and compensated. The SRC column shortenings are compared with the actual column shortening by field measurement and the column shortenings are reanalysed and recompensated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.18-29
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• 2013

A new precast concrete (PC) beam and column connection system using non-prestressed wire strands was recently developed. The system is composed of one unit of two-storied PC-column and PC-beams with U-shaped ends. The connection part of the column and beams is reinforced by deformed bars and non-prestressed wire strands in combination for the improvement of workability. Structural performance of this system was verified by several experimental studies. The purpose of this study is developing a design concept of the beam reinforced by deformed bars and non-prestressed wire strands in combination, in terms of the cross-sectional analysis, based on the preceded experiment. A minimum and maximum reinforcement ratio and the calculation formula for the strength of flexural member reinforced by reinforcements having different yield strengths are derived based on KBC2009. Under consideration existing research results for the application of high strength reinforcement bars, the design yield strength of the non-prestressed wire strand is suggested. An example for the cross section design, satisfying the serviceability requirements, demonstrates the applicability of the design concept developed in the study.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.137-140
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• 2006

In this study, a seismic performance of reinforced concrete columns strengthened by a sprayed fiber reinforced polymer (SFRP) is investigated. For this purpose, six column specimens approximately scaled into 2/3, are designed and tested under a constant axial load, 10% of the nominal axial strength of column, and pseudo-static reversed cyclic lateral loading system. Four specimens are strengthened by Sprayed FRP using different combinations of short fibers (carbon or glass fiber) and resins (epoxy or vinyl esther). For comparison, the test investigated in this study also includes a specimen strengthened using carbon fiber reinforced polymer (CFRP), and also a control specimen without strengthening. The results revealed that specimens strengthened using SFRP showed a improved structure behavior, compared to control specimen, in terms of strength, ductility, lateral drift capacity, and energy-absorbtion capacity. In addition, compared to the specimen strengthened using CFRP, Sprayed FRP-strengthened specimens reasonably showed a equivalent seismic performance.

• Journal of Korean Society of Steel Construction
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• v.24 no.4
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• pp.361-369
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• 2012

In this study, prefabricated composite columns using high-strength angles (PSRC composite column) was studied. Concentric axial loading tests were performed for 2/3 scale PSRC specimens and an conventional SRC specimen with H-steel at the center of the cross-section. The test parameters were the steel ratio of angles and the spacing of lateral re-bars. The test results showed that by placing the angles at the corners of the cross-section for confinement with provided for the core concrete, the PSRC column specimens exhibited greater load-carrying capacity and deformation capacity than those of the conventional SRC column. The axial load-carrying capacity of the PSRC columns was greater than the prediction by KBC 2009. Using existing stress-strain relationship of confined concrete, the axial load-deformation relationship of the specimens were predicted. The numerical predictions correlated well with the test results in terms of initial stiffness, load-carrying capacity, and post-peak strength- and stiffness-degradations.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.1
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• pp.1-7
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• 2003

The carbon composite tube can play an important role in replacing or complementing longitudinal and transverse reinforcing steels by providing ductility and strength for conventional columns. In this study, both the experimental and analytical investigations of axial behavior of large-scale square concrete columns confined by carbon composite tube are presented. The specimens are filament-wound carbon composite with 90$^{\circ}$+30$^{\circ}$, 90$^{\circ}$+45$^{\circ}$ winding angle respect to longitudinal axis of tube. The instrumented large-scale concrete-filled composite tubes(CFCT) are subjected to monotonic axial loads exerted by 10,000kN UTM. The influence of winding angle, thickness of tube on stress-strain relationships of the confined columns is identified and discussed. Proposed equations to predict both the strength and ductility of confined columns by carbon composite tube demonstrate good correlation with test data obtained from large-scale specimens.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.985-988
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• 2008

A linear analysis method using reduced secant stiffness was developed for inelastic earthquake design of reinforced concrete structures. In the proposed method, the beam-column element and plane element, which are the same as used in conventional elastic analysis, are used for structural modeling. Based on the structural plastic mechanism intended by engineer, the distribution of inelastic members is determined. The secant stiffness of the inelastic members is determined based on the target ductility of the structure. Inelastic strengths of the members are calculated by using linear analysis on the structure modeled with secant stiffness. Plastic rotations in the inelastic members are calculated with the nodal rotations resulting from the secant stiffness analysis. For verification, the proposed method was applied to the inelastic earthquake designs of a moment-resisting frame and a dual system of two dimensions, and also a dual system of three dimensions.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.419-420
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• 2010

High strength concrete(HSC) is made with Fiber-cocktail to control the spalling of HSC. In this paper, the column is made with PP fiber of $1.5kg/m^3$ and steel fiber of 20, 30, $40kg/m^3$, and the test are observed the temperature of reinforced bars and concrete. The results that increasing of temperature is delay as increase of steel fiber's volume.