• Journal of the Korea Concrete Institute
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• v.12 no.4
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• pp.59-67
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• 2000

With increased height of structure, the effect of column shortening need special consideration in the design and construction of high-rise buildings. The shortening of each column affects nonstructural members such as partitions, cladding, and M/E systems, which are not designed to carry gravity forces. The slabs and beams will tilt due to the cumulative differential shortening of adeacent vertical members. The main purpose of estimating the total shortening of vertical structural member is to compensate the differential shortening between adeacent members. This paper presents effect of parameters for phenomenon of column shortening in vertical members. The paper presents effect of parameters for phenomenon of column shortening in vertical members. The conclusions obtained from this study are follow as ; Strength of concrete and steel ratio effected on column shortening caused by elastic and inelastic shortening. Also, it is known that Ultimate-shrinkage-Value, Specific-Creep-Value, and volume to surface ratio effected on inelastic shortening only. Particularly, Ultimate-Shrinkage-Value and Specific-Creep-Value effected considerable on the amount of total column shortening.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.48-49
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• 2014

Green Frame is a column-beam system that uses composite precast concrete members. Previous studies have proven this system to be not only structurally safe, constructible, and economically feasible, but also environmentally-friendly. If the computerized program is used to estimate the quantity, the result of it shall be calculated much easily, quickly and exactly than manual estimation, because precast concrete members of Green Frame has standard size and connection method between it. Therefore, this study suggest quantity survey concept for column-beam structure comprised of composite precast concrete members. Hereafter, the quantity survey of Green Frame shall be much quickly and accurate, if the system would be made based on the result of this study.

• Structural Engineering and Mechanics
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• v.54 no.3
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• pp.521-543
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• 2015

Depending on the damage type as well as the level of damage observed after the earthquake, certain measures should be taken for the damaged buildings. In this study, structural repairing of two different types of damaged RC beam-column assembly by carbon fiber-reinforced polymer sheets is investigated in detail as a member repairing technique. Two types of 1:1 scale test specimens, which represent the exterior RC beam-column connection taken from inflection points of the frame, are utilized. The first specimen is designed according to the current Turkish Earthquake Code, whereas the second one represents a deficient RC beam-column assembly. Both of the specimens were subjected to cyclic quasistatic loading in the laboratory and different levels of structural damage were observed. The first specimen displayed a ductile response with the damage concentrated in the beam. However, in the second specimen, the beam-column joint was severely damaged while the rest of the members did not attain their capacities. Depending on the damage type of the specimens, the damaged members were repaired by CFRP wrapping with different configurations. After testing the repaired specimens, it is found that former capacities of the damaged members were mostly recovered by the application of CFRPs on the damaged members.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5984-5989
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• 2011

The buckling strength of a pin-ended column may be increased significantly by reinforcing it with an assemblage of cross-arm members rigidly connected to the modpoint of the column and stayed members connecting the ends of the columns and cross-arm members. The purpose of the stays and cross-arm members is to introduce restraint against translation and rotation and thereby decrease the effective buckling length of the column. In this study, buckling strengths of the reinforced columns were quantitatively evaluated from analytical solutions and elastic/inelastic finite elements analysis and the results were compared each other. It was found that the reinforcing system may increase the buckling strength up to 8 times compared to ones without reinforcing system.

• Structural Engineering and Mechanics
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• v.26 no.6
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• pp.651-672
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• 2007

This study presents an improved method that uses the elastic and inelastic system buckling analyses for determining the K-factors of steel column members. The inelastic system buckling analysis is based on the tangent modulus theory for a single column and the application is extended to the frame structural system. The tangent modulus of an inelastic column is first derived as a function of nominal compressive stress from the column strength curve given in the design codes. The tangential stiffness matrix of a beam-column element is then formulated by using the so-called stability function or Hermitian interpolation functions. Two inelastic system buckling analysis procedures are newly proposed by utilizing nonlinear eigenvalue analysis algorithms. Finally, a practical method for determining the K-factors of individual members in a steel frame structure is proposed based on the inelastic and/or elastic system buckling analyses. The K-factors according to the proposed procedure are calculated for numerical examples and compared with other results in available references.

• Journal of the Korean Society of Safety
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• v.35 no.3
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• pp.6-15
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• 2020

This study examined the structural behaviors and ultimate loads of assembled system scaffolds by load tests. Considering the number of bay and bracing installation, four specimens were tested. The bays were divided into 1 bay and 2 bays, with and without the bracing member installed. Failure modes and horizontal displacements show that the whole column buckled without showing no point of inflection in the column, regardless of whether or not braces were installed. Thus, the current design method of selecting the vertical spacing between the horizontal members of the system scaffold as the effective buckling length underestimates the effective buckling length. In case of 1 bay specimens, the ultimate loads between specimens with and with bracing members are similar. However, in case of 2 bay specimens, the specimen with bracing members shows the increased ultimate load of 36% compared with that without bracing members. In addition, as the number of bays in the system scaffold increases, the ultimate load of the unit vertical column increases in case of the specimen with bracing installation. However, in the specimen without bracing members, the ultimate load of the unit column reduces with the increment of the number of bays due to the torsional buckling. Therefore, it is essential to install bracing members to increase the whole strength of system scaffolds and the ultimate load of the unit column.

• Structural Engineering and Mechanics
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• v.63 no.3
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• pp.385-400
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• 2017

This paper presents an experimental study on the behavior of axially-loaded steel RHS (rectangular hollow section) compression members that are partially reinforced along their lengths with welded steel plates. 28 slender column tests were carried out to investigate the effects of the slenderness ratio of the unreinforced member and the ratio of the reinforced length of the member to its entire length. In addition to the slender column tests, 14 stub-column tests were conducted to determine the basic mechanical properties of the test specimens under uniform compression. Test results show that both the compressive strength and stiffness of an RHS member can be increased significantly compared to its unreinforced counterpart even when only the central quarter of the member is reinforced. Based on the limited test data, it can be concluded that partial reinforcement is, in general, more effective in members with larger slenderness ratios. A simple design expression is also proposed to predict the compressive strength of RHS columns partially reinforced along their length with welded steel plates by modifying the provisions of AISC 360-10 to account for the partial reinforcement.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.267-274
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• 1996

Differential shortening of vertical members in high-rise buildings affect other structural members that have to be considered such as horizontal members and exterior cladding. of many elements which affect the total amount of shortening, different loading history mainly comes from the different construction time. Shortening of 66 story concrete columns were investigated and compared according to the different construction time, little difference was found between the total shortening of interior and that of exterior column.

• Journal of Korean Society of Steel Construction
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• v.11 no.3 s.40
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• pp.311-318
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• 1999

Concrete filled tubular(CFT) members have many structural and constructional advantages. The prefabrication of CFT members can be thought an idea for the good qualify control of concrete. The objective of this study is to suggest the construction method of prefab CFT beam-columns. Tests are performed to understand their structural behaviors. The opening space between prefab CFT members and the size of tubular members are the parameters of this study. The results of this study will be based on the suggestion of prefab CFT.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.25-28
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• 2005

The elastic buckling load or strength of a concentrically loaded slender metal column may be increased many times by reinforcing it with an assemblage of pretensioned stays and rigidity connected crossarm members. The complete system is herein referred to as a 'stayed column'. The purpose of the pretensioned stays and crossarm members is to introduce, at several points along the length of the column, restraint against translation and rotation and thereby decrease the effective unsupported buckling length of the column. This paper verifies that pretensioned cable of stayed column is effective for cyclic load and increases strength of shear wall against earthquake by reinforcing side of wall. Design process of stayed column which satisfies demanded capacity and ductility of wall is presented by analyzing result of experiment.