• Journal of Korean Association for Spatial Structures
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• v.18 no.3
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• pp.37-44
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• 2018

A base isolation system is widely used to reduce seismic responses of low-rise buildings. This system cannot be effectively applied to high-rise buildings because the initial stiffness of the high-rise building with the base isolation system maintains almost the same as the building without the base isolation system to set the yield shear force of the base isolation system larger than the design wind load. To solve this problem, the mid-story isolation system was proposed and applied to many buildings. The mid-story isolation system has two major objectives; first to reduce peak story drift and second to reduce peak drift of the isolation story. Usually, these two objectives are in conflict. In this study, a hybrid mid-story isolation system for a tall building is proposed. A MR (magnetorheological) damper was used to develop the hybrid mid-story isolation system. An existing building with mid-story isolation system, that is "Shiodome Sumitomo Building" a high rise building having a large atrium in the lower levels, was used for control performance evaluation of the hybrid mid-story isolation system. Fuzzy logic controller and genetic algorithm were used to develop the control algorithm for the hybrid mid-story isolation system. It can be seen from analytical results that the hybrid mid-story isolation system can provide better control performance than the ordinary mid-story isolation system and the design process developed in this study is useful for preliminary design of the hybrid mid-story isolation system for a tall building.

• Journal of Korean Association for Spatial Structures
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• v.7 no.1 s.23
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• pp.45-53
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• 2007

Recently, high-rise base isolated building structures with shear keys are often constructed in Japan which frequently occurs earthquakes. High-rise buildings are less damaged because those buildings have longer natural period than md or low rise buildings. The shear key is device that prevents the base isolators operating by the wind loads not by the earthquake loads. In case of big base shear force acts on the shear keys by earthquake, this device is broken and base isolator is operated. Therefore, seismic intensities play a role in acting on the shear keys. If wind loads are hither than the earthquake loads, the shear keys designed by wind loads are not operated in earthquakes. So, the requirements of shear keys in high-rise base isolated building structures must be examined in Korea with moderate seismic legions. In this study shear keys are applied with 5 and 15 stories base isolated building structures and investigated their dynamic responses to original and 1/2 scale downed El Centre NS(1940) ground motions. The results show that the yield shear forces of the shear keys affect significantly the dynamic behavior of base isolated building structures

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.2
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• pp.15-23
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• 2012

This study was accomplished by analyzing the change of land cover pattern in high-rise buildings in Korea. For this study, we selected 15 locations of high-rise buildings. The ratio of average building coverage and paved area was 79.7%, and both green and water area were low, relatively. The biotope area factor of the site showed low percentage by 15.90% due to the underground space development. As a result of correlation analysis between the time of construction and land-cover type, building coverage has been decreased according to the stream of time. However, biotope area factor has been increased And, the paved area has m correlation. It was identified that reducing paved area is effective to enhance the ecological functions of a high-rise building outdoor.

• Earthquakes and Structures
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• v.11 no.6
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• pp.967-982
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• 2016

Current codes design the buildings based on life safety criteria. In a performance-based design (PBD) approach, decisions are made based on demands, such as target displacement and performance of structure in use. This type of design prevents loss of life but does not limit damages or maintain functionality. As a newly developed method, resilience-based design (RBD) aims to maintain functionality of buildings and provide liveable conditions after strong ground movement. In this paper, the seismic performance of plain and strengthened RC frames (an eight-story and two low-rise) is evaluated. In order to evaluate earthquake performance of the frames, the performance points of the frames are calculated by the capacity spectrum method (CSM) of ATC-40. This method estimates earthquake-induced deformation of an inelastic system using a reduced response spectrum. Finally, the seismic performances of the frames are evaluated and the results are compared with a resilience-based design criterion.

• Wind and Structures
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• v.15 no.4
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• pp.313-329
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• 2012

There have existed for a number of years good practice guidelines for the use of Computational Fluid Dynamics (CFD) in the field of wind engineering. As part of those guidelines, details are given for the size of flow domain that should be used around a building of height, H. For low-rise buildings, the domain sizes produced by following the guidelines are reasonable and produce results that are largely free from blockage effects. However, when high-rise or tall buildings are considered, the domain size based solely on the building height produces very large domains. A large domain, in most cases, leads to a large cell count, with many of the cells in the grid being used up in regions far from the building/wake region. This paper challenges this domain size guidance by looking at the effects of changing the domain size around a tall building. The RNG ${\kappa}-{\varepsilon}$ turbulence model is used in a series of steady-state solutions where the only parameter varied is the domain size, with the mesh resolution in the building/wake region left unchanged. Comparisons between the velocity fields in the near-field of the building and pressure coefficients on the building are used to inform the assessment. The findings of the work for this case suggest that a domain of approximately 10% the volume of that suggested by the existing guidelines could be used with a loss in accuracy of less than 10%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.7
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• pp.288-292
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• 2016

The purpose of this study was to improve the refuge safety area in the high-rise building type. Each simulation was conducted to evaluate the performance of three types in improving the refuge safety area. Targeting the first 63 floors (no refuge safety area), secondly, to target up to the $30^{th}$ floor (refuge safety area on the $30^{th}$ floor, $47^{th}$ floor) specified in domestic laws, and finally, the $20^{th}$ floor (evacuation safety area on the $20^{th}$ floor, $42^{th}$ floor) were considered as targets. Through this analysis, the following results were obtained : The floor for the refuge safety area through simulations showed that the evacuation time is low. It is necessary to improve the floor for the refuge safety area by using the characteristics of the domestic fire fighting vehicle. The first floor for the refuge safety area from the ground floor differs according to the distance and height of the building floor. However, in the case of a business facility it is 15F, and in the case of apartment housing, it is 20F.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.237-240
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• 2008

The objective of this study is to evaluate the seismic performance of the low-rise RC apartment buildings having piloties at ground level by using nonlinear static analysis with regards to the maximum considered and design earthquakes in Korea. To do this, the target displacement at roof was estimated according to FEMA356 (or ASCE/SEI-41), and the deformations of the critical members were compared with the failure criteria of Life Safety(LS) and Collapse Prevention(CP) given in FEMA356. The conclusions are as follows: (1) columns satisfy criteria of LS and CP, but (2) the shear wall in the longitudinal direction failed to satisfy those of both LS and CP while those in the transverse direction satisfy that of LS, but failed that of CP.

• Wind and Structures
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• v.5 no.1
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• pp.25-48
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• 2002

Wind flow and pressure on the roof of the Texas Tech Experimental Building are studied along with the incident wind in an effort to understand the wind-structure interaction and the mechanisms of roof pressure generation. Two distinct flow phenomena, cornering vortices and separation bubble, are investigated. It is found for the cornering vortices that the incident wind angle that favors formation of strong vortices is bounded in a range of approximately 50 degrees symmetrical about the roof-corner bisector. Peak pressures on the roof corner are produced by wind gusts approaching at wind angles conducive to strong vortex formation. A simple analytical model is established to predict fluctuating pressure coefficients on the leading roof corner from the knowledge of the mean pressure coefficients and the incident wind. For the separation bubble situation, the mean structure of the separation bubble is established. The role of incident wind turbulence in pressure-generation mechanisms for the two flow phenomena is better understood.

• Earthquakes and Structures
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• v.8 no.6
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• pp.1435-1452
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• 2015

The performance of masonry infilled frames during the past earthquakes shows that the infill panels play a major role as earthquake-resistant elements. Experimental observations regarding the influence of infill panels on increasing stiffness and strength of reinforced concrete structures reveal that such panels can be used in order to strengthen reinforced concrete frames. The present study examines the influence of infill panels on seismic behavior of RC frame structures. For this purpose, several low- and mid-rise RC frames (two-, four-, seven-, and ten story) were numerically investigated. Reinforced masonry infill panels were then placed within the frames and the models were subjected to several nonlinear incremental static and dynamic analyses. In order to determine the acceptance criteria and modeling parameters for frames as well as reinforced masonry panels, the Iranian Guideline for Seismic Rehabilitation of Existing Masonry Buildings (Issue No. 376), the Iranian Guideline for Seismic Rehabilitation of Existing Structures (Issue No. 360) and FEMA Guidelines (FEMA 273 and 356) were used. The results of analyses showed that the use of reinforced masonry infill panels in RC frame structures can have beneficial effects on structural performance. It was confirmed that the use of masonry infill panels results in an increment in strength and stiffness of the framed buildings, followed by a reduction in displacement demand for the structural systems.

• Journal of the Korean Institute of Rural Architecture
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• v.3 no.3
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• pp.57-67
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• 2001

The evolution of multi-family housing in Cheongju can be divided by four stages which are a introduction period from 1972 to 1980, a popularization period from 1981 to 1989, a expansion period from 1990 to 1997, and a stagnation period after 1998. In the introduction period, the multi-family housings were mainly low-rise buildings because a government policy which focused on extension of the apartments for the low-income influenced multi-family housing constructions. During the popularization period, the multi-family housings were still low-rise but houses in various sizes were introduced. That was because the Housing Site Developments were started and private companies' participations followed them increasingly. As a result of vigorous participations of private companies and massive developments of housing sites, the multi-family housings in the expansion period started to show constructions of complex and trends of high density and high rising. Finally, in the stagnation period, a rate of the supply of the small houses, whose size was below $60m^2$ of exclusive, area was increased and extreme high-rise apartments emerged. High rising and density were the mainstream of the construction concepts. During this period, the growth of multi-family housing marked low. The reason was that a downturn in economy led private companies to shrink their constructions.