• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.490-495
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• 2006

The analysis method proposed by PCA is widely used in calculating the column shortening of reinforced and composite columns of a tall building. However, residual creep factor which relates creep strain of reinforced concrete to creep strain of plain concrete is based on Rate of Creep Method (RCM) which has theoretical defects and is considered obsolete. In this paper, a new equation for the residual creep factor based on Age-adjusted Effective Modulus Method (AEMM) which is considered exact and better than RCM is proposed. The residual creep factor by RCM is found to be higher than one by AEMM, which means current PCA method overestimates the shortening of a reinforced concrete column. By using the residual creep factor by AEMM, more exact column shortening of a tall building can be obtainable with a simple modification to PCA method.

• International Journal of High-Rise Buildings
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• v.6 no.1
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• pp.91-99
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• 2017

Special consideration should be given to differential column shortening during the design and construction of a tall building to mitigate the adverse effects caused by such shortening. The effects of the outrigger - which is conventionally used to increase the lateral stiffness of a tall building - on the differential shortening are investigated in this study. Three analysis models, a constant-section, constant-stress, and general model, are prepared, and the differential shortenings of these models with and without the outrigger are compared. The effects of connection time, sectional area, and location of the outrigger on the differential shortening are studied. The sectional area of the outrigger shows a non-linear relation in reducing the maximum differential shortening. The optimum locations of the single and dual outriggers are investigated by an exhaustive search method, and it is confirmed that a global optimum location exists. This study shows that the outrigger can be utilized to reduce the differential shortening between the interior core wall and the perimeter columns as well as to reduce the lateral displacements due to wind or earthquake loads.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.11a
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• pp.33-36
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• 2003

Time-dependent axial shortening in the cores and columns of tall concrete buildings requires special attention to ensure proper behavior for strength of the structure and the nonstructural clement. The effects of column shortening, both elastic and inelastic, take on added significance and need special consideration in design and construction with increased height of structures. In this paper, the compensation method of column shortening are introduced. It could be conclued that the survey is a significant factor for the compensation of column shortening.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.33-36
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• 2003

Time-dependent axial shortening in the cores and columns of tall concrete buildings requires special attention to ensure proper behavior for strength of the structure and the nonstructural element. The effects of column shortening, both elastic and inelastic, take on added significance and need special consideration in design and construction with increased height of structures. In this paper, the compensation method of column shortening are introduced. It could be concluded that the survey is a significant factor for the compensation of column shortening.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.4
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• pp.237-244
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• 2020

This study investigates the effect of the outrigger wall reinforced with post-tension on reducing differential column shortening. Since the outrigger wall is a concrete structure, the effect of its long-term behavior should be considered. The long-term behavior of the outrigger wall increases differential column shortening and decreases the shear force acting on the outrigger. When the stiffness of the outrigger becomes small, the effect of its long-term behavior increases. Furthermore, a method of reinforcing with post-tension to reduce differential column shortening is proposed. Following the analysis, it was confirmed that the post-tension method shows a significant reduction in the differential column shortening. This study shows that the effect of the outrigger wall reinforced with post-tension on reducing differential column shortening increases with the prestressing force of tendon.

• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.36-42
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• 2004

Although steel-reinforced concrete(SRC) is widely used in a high-rise building, a methods used to predict the column shortening of SRC structural members has many problems in applying a theoretical equation which considers only the material characteristics of reinforced concrete. In this study, the degree of accuracy of the existing method calculating the column shortening of a high-rise building is examined. For this, first, the actual measurement data are chosen about the column shortening of a high-rise building established with SRC structural members. Then the column shortening of a SRC structural member is calculated through computer program. Finally, the comparison between the measurement data and the analytical ones is executed. According to this study, it can be concluded that there is little difference between the former and the latter. Therefore, the existing method can be used to evaluate the column shortening of a high-rise building using a SRC structural members.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.3
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• pp.59-68
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• 1997

The necessity of a high-rise building in big cities gave a new problem to structural engineers. The shortening effect of vertical members needs special considerstion in the desigh and construction of high-rise buildings. The shortening of each column transfers load to nonstructural members such as partitions, cladding, and M/E systems which are not designed to carry gravity loads. Also, the slabs and beams will tilt due to the cumulative differential shortening of adjacent vertical members. The main purpose of estimating the total shortening of vertical structural members is to compensate the differential shortening between adjacent members. This paper presents the structural effect of differential shortening between in main structural members. Lateral earthquake load is applied to the 52 story concrete structure which has an initial vertical displacement due to the gravity load. Shortening amount for each vertical member was estimated using the computerized column shortening software. Comparison of stresses between the shortening corrected structure and the uncorrecated structure due to earthquake load was discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.2
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• pp.189-197
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• 2008

This study presents optimal compensation algorithm of differential column shortening for more than two column groups. The proposed algorithm produces the minimum story groups and their compensation thicknesses which satisfy constraint conditions on performance and construction and enables not only the relative compensation but also the mixed compensation considering absolute shortening. The simulated annealing algorithm is used as the main optimization technique. The applicability of the proposed algorithm was verified by applying it to the 61-storey building where compensation of differential column shortening had already been performed. Using, the proposed algorithm compensation was performed easily and the number of compensation was less than the field method.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.142-147
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• 1993

In the reinforced concrete structure, as the height of building structure increases, the accurate estimation of differential column shortening is important factor in the structural design. In this study, the analysis of column shortening is applied to 36-story building structure to be built in time. As a result, it may found that, as the difference of compressive stress become larger, differential shortening effect due to creep and shrinkage are more signicant factor to structural designer.