• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.31-34
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• 2009

Large outrigger elements tie the concrete core to perimeter columns, significantly increasing the building's lateral stiffness as well as its resistance to overturning due to wind. The outriggers are deep elements, and large tie forces are resisted by top and bottom heavy longitudinal reinforcing and vertical ties. To reduce construction costs, all primary reinforcing bars in outrigger levels are SD500. Further, concrete strengths of 80MPa have been specified for outrigger elements. However, the reductions in the amount of concrete and reinforcement steel are more increased in tall building. With these backgrounds, 80MPa high strength concrete outrigger system using post tension method is developed. Significant economic savings can be made by reducing the element sizes and material content. The developed outrigger system is designed using strut-and-tie models. In addition, four 1/4-scale test specimens were selected from the same prototype structure. The results from the tests are confirmed that the structural behaviors of the developed outrigger member have better capacities than those of a conventional method.

• Journal of Korean Association for Spatial Structures
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• v.17 no.2
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• pp.43-51
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• 2017

The demand for skyscrapers is increasing worldwide. Until now, various lateral resistance structures have been used for lateral displacement control of high-rise buildings. An outrigger damper system has been introduced recently to improve lateral dynamic response control performance further. However, a study of outrigger damper system is yet to be sufficiently investigated. In this study, time history analysis was performed to investigate the control performance of an outrigger damper system of high-rise building under eccentric loading. To do this, an actual scale 3-dimensional tall building model with an outrigger damper system was prepared. The control performance of the outrigger damper system was evaluated by varying stiffness and damping values. On the top floor torsional angle response to the earthquake load, was greatly affected by damping value. And the displacement response was affected greatly by the stiffness value and damping value of damper system. In conclusion, it is necessary to select the proper damping and stiffness values of the outrigger damper system.

• Advances in Computational Design
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• v.7 no.1
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• pp.19-35
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• 2022

In this paper, the optimum location of the belt truss-outrigger for a combined system of framed tube, shear core and outrigger-belt truss is calculated. The optimum location is determined by maximization of the first natural frequency. The framed tube is modeled using a non-prismatic cantilever beam with hollow box cross section. The governing differential equation is solved using the weak form integral equations and the natural frequencies of the structure are calculated. The graphs are introduced for quick calculation of the first natural frequency. The location of the belt truss-outrigger that maximizes the first natural frequency of the structure is introduced as an optimum location. The structure is modeled using SAP-2000 finite elements software. In the modelling, the location of the belt truss-outrigger is changed along the height of the structure. With various locations of the outrigger, the lateral deflection of the all stories and axial force in the columns of the outer tube are calculated. The analysis is repeated by locating the outrigger-belt truss at the optimum location. The analysis results are compared and effect of the optimum location on the lateral deflection and the shear lag phenomena are investigated.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.3
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• pp.291-299
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• 2003

Based on the continuum approach, an investigation is made to get the forces and displacements of laterally loaded outrigger braced structures with a pair of coupled cores, and to show the effect of stiffening outriggers on the behavior of the structure. From the condition that the rotation of the core at the outrigger level is matched with the rotation of the corresponding outrigger, the outrigger restraining moment is derived analytically. From this, the core moment diagram, the column axial forces, and the horizontal displacements of the structure may be determined. Comparisons with the results by the program MIDAS-GEN for the structural models, have shown that this analysis can give reasonably accurate results for outrigger-braced structures with a pair of coupled cores. And a lateral displacement at the top of the structure is influenced by the outrigger location than the core location. Although the formulae are accurate only for idealized outrigger braced structures, they have a useful practical purpose in providing a guide to the behavior, and for making approximate estimates of the forces and displacements, in practical outrigger braced structures with a pair of coupled cores.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.40-49
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• 2013

This study purposed to investigate the optimal outrigger location in tall building with cap truss after a structural schematic design of 80 stories building was performed by using MIDAS-Gen. In this paper, the main parameters of structural analysis were the outrigger location and stiffness of main structural elements (outrigger, exterior column, shear wall etc). In order to search the optimal outrigger position in high-rise building with cap truss, we analysed and examined the lateral displacement of top floor which is one of the very important considering factors of tall building structural design. The paper results indicated that the outrigger location and the stiffness of main structural elements such as outrigger, exterior column and shear wall had an effect on the optimal outrigger location. And it is verified that the study results provided the basic engineering data for fixing the most optimal outrigger location for minimizing the lateral displacement of tall building.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.45-52
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• 2018

The paper aimed to find out the lateral behavior of outrigger system in high-rise building considering floor diaphragm. To achieve this goal, a structural schematic design of 80 stories building was conducted by utilizing MIDAS-Gen. In this research, the key parameters of the structure analysis were the outrigger location in plan, the slab stiffness, the outrigger stiffness and the kind of diaphragm. For the purpose of this study, we analyzed and studied the lateral displacement in top floor, the story drift and the stress in slab. The research results indicated that the outrigger location in plan, the slab stiffness, the outrigger stiffness and the kind of diaphragm had an effect on lateral behavior in outrigger system of tall building. And the results of this analysis research can provided the assistance in getting the basic data of structure design for looking for the lateral behavior of outrigger system in the high-rise building.

• 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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• 2015.05a
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• pp.190-191
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• 2015

Construction delays occur frequently in outrigger framework of tall buildings due to the unexpected conditions and lack of experience. However, delay factors of the outrigger framework has not been managed efficiently. Therefore, the systematic management is needed by perceiving possible delay factors before constructing management system. In this study, the major delay factors of outrigger framework are conducted to derive by using the Importance Performance Analysis(IPA). It is expected that the results of this study are utilized for planning of systematic scheduling in outrigger framework of tall building.

• Structural Engineering and Mechanics
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• v.74 no.2
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• pp.267-282
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• 2020

The seismic performance and failure modes of the dual system of moment resisting frames and thin steel plate shear walls (TSPSWs) without and with one or two outrigger trusses are studied in this paper. These structural systems were utilized to resist vertical and lateral loads of 40-storey buildings. Detailed Finite element models associated with nonlinear time history analyses were used to examine seismic capacity and plastic mechanism of the buildings. The analyses were performed under increased levels of earthquake intensities. The models with one and two outriggers showed good performance during the maximum considered earthquake (MCE), while the stress of TSPSWs in the model without outrigger reached its ultimate value under this earthquake. The best seismic capacity was in favour of the model with two outriggers, where it is found that increasing the number of outriggers not only gives more reduction in lateral displacement but also reduces stress concentration on thin steel plate shear walls at outrigger floors, which caused the early failure of TSPSWs in model with one outrigger.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.3
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• pp.11-18
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• 2018

Due to the recent overpopulation of urban cities, land shortage and soaring land prices have caused an increase in the demand for high-rise buildings. To build buildings on a limited land, the size of the building is important. Displacement control by horizontal loads in a skyscraper is critical to securing stability and usability of structures. Several systems have been proposed for efficient horizontal displacement control, and so far the study continues. Among them, the Outrigger System is a representative of the typical horizontal load resistance system. Although studies have been conducted so far to locate the optimal position of the outrigger, studies of the slenderness ratio of the buildings are still insufficient. Based on the Outrigger-Optimized Position equation, this study induces the calculation of the displacement of the outrigger installation building according to the slenderness ratio.