• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.183-194
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• 2017

This paper presents the experimental investigation into a new type of steel-concrete hybrid outrigger system developed for the high-rise building structure. The steel truss is embedded into the reinforced concrete outrigger wall, and both the steel truss and concrete outrigger wall work compositely to enhance the overall structural performance of the tower structures under extreme loads. Meanwhile, metal dampers of low-yield steel material were also adopted as a 'fuse' device between the hybrid outrigger and the column. The damper is engineered to be 'scarified' and yielded first under moderate to severe earthquakes in order to protect the structural integrity of important structural components of the hybrid outrigger system. As such, not brittle failure is likely to happen due to the severe cracking in the concrete outrigger wall. A comprehensive experimental research program was conducted into the structural performance of this new type of hybrid outrigger system. Studies on both the key component and overall system tests were conducted, which reveal the detailed structural response under various levels of applied static and cyclic loads. It was demonstrated that both the steel bracing and concrete outrigger wall are able to work compositely with the low-yield steel damper and exhibits both good load carrying capacities and energy dispersing performance through the test program. It has the potential to be applied and enhance the overall structural performance of the high-rise structures over 300 m under extreme levels of loads.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.561-566
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• 2009

The outrigger system with a core is widely used for lateral load resisting system of tall building. Recently, structural systems in tall building are adopted to eccentric core and offset outrigger or one-armed outrigger system by trends in planning buildings of irregular type. Therefore, the performance of outrigger system with eccentric core in tall building is evaluated by 50-stories examples which are analyzed for variables such as layout of core and outrigger, arm length of outrigger and depth of outrigger and belt wall.

• International Journal of High-Rise Buildings
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• v.5 no.1
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• pp.21-30
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• 2016

The structural efficiency of tall buildings heavily depends on the lateral stiffness and resistance capacity. Among those structural systems for tall buildings, outrigger system is one of the most common and efficient systems especially for those with relatively regular floor plan. The use of outriggers in building structures can be traced back from early 50 from the concept of deep beams. With the rise of building height, deep beams become concrete walls or now in a form of at least one story high steel truss type of outriggers. Because of the widened choice in material to be adopted in outriggers, the form and even the objective of using outrigger system is also changing. In the past, outrigger systems is only used to provide additional stiffness to reduce drift and deflection. New applications for outrigger systems now move to provide additional damping to reduce wind load and acceleration, and also could be used as structural fuse to protect the building under a severe earthquake condition. Besides analysis and member design, construction issue of outrigger systems is somehow cannot be separated. Axial shortening effect between core and perimeter structure is unavoidable. This paper presents a state-of-the-art review on the outrigger system in tall buildings including development history and applications of outrigger systems in tall buildings. The concept of outrigger system, optimum topology, and design and construction consideration will also be discussed and presented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.1-11
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• 2021

The research intended to understand the lateral behavior in core and offset outrigger system. To achieve this goal, a structural analysis and design of 70 stories building was carried out by making use of MIDAS-Gen. And the primary parameters of this analysis were the stiffness of outrigger and the location of outrigger in plan. On the basis of the analysis results, we analyzed the lateral behavior of structural elements such as slab, outrigger and exterior columns in core and offset outrigger. In this analysis research, it is indicated that the stiffness of outrigger and the outrigger location in plan had an any impact on lateral behavior in outrigger system of tall building. Specially, slab stresses in core outrigger system were highly distributed in the slab near the outrigger system to connect shear walls and exterior columns while slab stresses in offset outrigger system were highly distributed in the slab between the outrigger system and shear walls. Also the study results can be of significant help to obtaining the engineering data for the reasonable structure design of the high-rise outrigger system.

• Structural Engineering and Mechanics
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• v.86 no.4
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• pp.503-518
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• 2023

In tall constructions, the outriggers are regarded as a structural part capable of effectively resisting lateral loads. This study analyses the efficacy of hybrid outrigger system in high rise RCC building for various structural parameters identified. For variations in α, which is defined as the ratio of the relative flexural stiffness of the core to the axial rigidity of the column, static and dynamic analyses of hybrid outrigger system having a virtual and a conventional outrigger at two distinct levels were conducted in the present study. An investigation on the optimal outrigger position was performed by taking the results from absolute maximum inter storey drift ratio (ISD_max), roof acceleration (acc_roof), roof displacement (disp_roof), and base bending moment under both wind and seismic loads on analytical models having 40, 60 and 80 storeys. An ideal performance index parameter was introduced and was utilized to obtain the optimal position of the hybrid outrigger system considering the combined response of ISD_max, acc_roof, disp_roof and, criteria required for the structure under wind and seismic loads. According to the behavioural study, increasing the column area and outrigger arm length will maximise the performance of the hybrid outrigger system. The analysis results are summarized in a flowchart which provides the optimal positions obtained for each dependent parameter and based on ideal performance index which can be used to make initial suggestions for installing a hybrid outrigger system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.16-24
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• 2017

The purpose of this paper is to search the optimal location of offset outrigger system in high-rise building after a structural schematic design of 80 stories building was conducted, making use of MIDAS-Gen. In this research, the key factors of analysis study were column stiffness, outrigger position in plan and outrigger location in height. For the aim of finding out the optimum position of offset outrigger system in tall building, we studied the lateral displacement in top floor which is the very essential variables in the structural design of high-rise building. The results of study showed that the column stiffness, the outrigger location in plan and outrigger location in height had an effect on the optimal position of outrigger system. Also, it is indicated that the research results can be useful in acquiring the structural design materials for seeking the optimum position of offset outrigger system in tall building.

• International Journal of High-Rise Buildings
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• v.4 no.3
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• pp.209-217
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• 2015

Outrigger systems are highly efficient since they utilize the perimeter zone to resist lateral forces, similar to tubular systems. The entire structural weight can be reduced due to the system's significant lateral strength. Therefore, it is the most commonly selected structural system for tall and supertall buildings built in recent years. In this paper, issues regarding the differential shortening effect during construction of the outrigger system and the special joints used to solve these issues will be addressed. Additionally, the characteristics of wind and seismic loads in Korea will be briefly discussed. Lastly, buildings in Korea using an outrigger as their major structural system will be introduced and the structural role of the system will be analyzed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.22-32
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• 2015

This study intended to analyze an influence of the structure elements on the optimal location for one-outrigger system in tall building by using MIDAS-Gen. In this investigation, the analysis parameters were the outrigger position and the stiffness of main structure elements such as shear walls, outrigger systems, exterior columns connected in outrigger system and frames not to be connected in outrigger system. For the objective of finding out the optimal location for one-outrigger system in high-rise building, we studied the lateral displacement in top level of 80 stories building. The results of this study indicated that the outrigger location and the stiffness of main structure elements such as shear walls, outrigger systems, exterior columns connected in outrigger system and frames not to be connected in outrigger system had an influence on the optimal location of one-outrigger system. In addition, it is showed that the research results can be very useful in obtaining the structure design data for looking for the optimal location of one-outrigger system in high-rise building.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.139-145
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• 2018

An outrigger system is used widely to increase the lateral stiffness of high-rise buildings, resulting in reduced dynamic responses to seismic or wind loads. Because the dynamic characteristics of earthquake or wind loads are quite different, a smart vibration control system associated with an outrigger system can be used effectively for both seismic and wind excitation. In this study, an adaptive smart structural control system based on an outrigger damper system was investigated for the response reduction of multi-hazards, including seismic and wind loads. A MR damper was employed to develop the smart outrigger damper system. Three cities in the U.S., L.A., Charleston, and Anchorage, were used to generate multi-hazard earthquake and wind loads. Parametric studies on the MR damper capacity were performed to investigate the optimal design of the smart outrigger damper system. A smart control algorithm was developed using a fuzzy controller optimized by a genetic algorithm. The analytical results showed that an adaptive smart structural control system based on an outrigger damper system can provide good control performance for multi-hazards of earthquake and wind loads.

• International Journal of High-Rise Buildings
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• v.5 no.1
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• pp.13-20
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• 2016

Today's architecture can be best understood only through the recognition of pluralism, and, as is true of other building types, multiple design directions are prevalent for tall buildings. This contemporary design trend has produced many complex-shaped tall buildings, such as twisted, tilted and tapered form towers. Among many different structural systems developed for tall buildings, the outrigger system, with its inherent structural efficiency and flexibility in façade design, is widely used for contemporary tall buildings. This paper studies structural performance of outrigger systems employed for complex-shaped tall buildings. Twisted, tilted and tapered tall buildings are designed with outrigger structures, and their structural performance is investigated. For the twisted outrigger study, the buildings are twisted up to 3 degrees per floor. In the tilted outrigger study, the angles of tilting range from 0 to 13 degrees. The impact of eccentricity is investigated for gravity as well as lateral loads in tilted towers. In the study of tapered outrigger structures, the angles of tapering range from 0 to 3 degrees. Parametric structural models are generated using appropriate computer programs for these studies, and the models are exported to structural engineering software for design and analyses.