• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1997년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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• pp.167-174
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• 1997

Viscoelastic dampers have been successfully applied in building structures to reduce vibration by wind and earthquakes. It may be inefficient or be uneconomical that viscoelastic damper is installed at each story of building structures. Although the number of viscoelastic dampers is reduced, if viscoelastic dampers are installed at only suitable places in building structures, vibration would be controlled by efficiency. In this paper, responses of building structures according to the situation of viscoelastic dampers are compared. Then efficient and economical arrangements of viscoelastic dampers are proposed.

• 국제초고층학회논문집
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• 제5권4호
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• pp.251-262
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• 2016

Tall Buildings have been one of the most prominent symbols of economic growth for nearly a century. Yet, in the aftermath of the tragedies of September 11, "signature" Tall buildings have become the focus of much debate. The structural systems today are undergoing a major evolution to address the ability of providing flexibility in the design and use of the building together with sustainability (Green) and cost-effective system. This paper describes a new invented structural system, evolutionary structural analysis and design of Tall buildings, which involves the entire analysis process, including conceptual and design stages and comparison with the existing Tall building. This study presents an new innovative structural system, Beehive (Hexagrid), for Tall buildings. The final results are achieved by modeling an 80 story Tall building with the optimized angle and topology of hexagon members by using a computer analysis, ETABS finite element analysis. The objective function of this system is to use one structural system in order to both maximize Eigen frequency for resisting dynamic responses and minimize mean compliance for static responses. Finite element analysis is carried out by using standardized materials. Optimal Hexagrid topologies with the highest stiffness are finally determined to resist both static and dynamic behaviors. Holistic design integration approaches between structures and facades to save energy for environmental control are studied. Innovative design ideas to control structural motion as well as to utilize that motion to harness energy are discussed. Considering abundant emergence of tall buildings all over the world in recent years, the importance of the studies presented in this paper cannot be overemphasized for constructing more sustainable built environments.

• 한국공간구조학회논문집
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• 제18권3호
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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.

• Wind and Structures
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• 제18권6호
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• pp.599-618
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• 2014

In this study, a square rectangular tall building is considered to investigate the effects of turbulence integral length scale and turbulence intensity on the along-wind responses, across-wind responses and torsional responses of the tall building by Large Eddy Simulation (LES). A recently proposed inflow turbulence generator called the discretizing and synthesizing random flow generation (DSRFG) approach is applied to simulate turbulent flow fields. It has been proved that the approach is able to generate a fluctuating turbulent flow field satisfying any given spectrum, desired turbulence intensity and wind speed profiles. Five profiles of turbulence integral length scale and turbulence intensity are respectively generated for the inflow fields by the DSRFG approach for investigating the effects of turbulence integral length scale and turbulence intensity on the wind-induced responses of the tall building. The computational results indicate that turbulence integral length scale does not have significant effect on the along-wind (displacement, velocity and acceleration) responses, across-wind displacement and velocity responses, while the across-wind acceleration and torsional responses vary without a clear rule with the parameter. On the other hand, the along-wind, across-wind and torsional responses increase with the growth of turbulence intensity.

• Wind and Structures
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• 제15권4호
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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%.

• Wind and Structures
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• 제30권6호
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• pp.597-616
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• 2020

The blockage effect on the aerodynamic characteristics of tall buildings is a fundamental issue in wind tunnel test but has rarely been addressed. To evaluate the blockage effects on the aerodynamic forces on a square tall building and flow field peripherally, large eddy simulations (LES) were performed on a 3D square cylinder with an aspect ratio of 6:1 under the uniform smooth inflow and turbulent atmospheric boundary layer (ABL) inflow generated by the narrowband synthesis random flow generator (NSRFG). First, a basic case at a blockage ratio (BR) of 0.8% was conducted to validate the adopted numerical methodology. Subsequently, simulations were systematically performed at 6 different BRs. The simulation results were compared in detail to illustrate the differences induced by the blockage, and the mechanism of the blockage effects under turbulent inflow was emphatically analysed. The results reveal that the pressure coefficients, the aerodynamic forces, and the Strouhal number increase monotonically with BRs. Additionally, the increase of BR leads to more coherence of the turbulent structures and the higher intensity of the vortices in the vicinity of the building. Moreover, the blockage effects on the aerodynamic forces and flow field are more significant under smooth inflow than those under turbulent inflow.

• 건축역사연구
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• 제9권3호
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• pp.51-69
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• 2000

This study tries to analyze the development of architectural technologies appeared in several tall buildings and large spatial structures from 1955 to 1999 in Korea. We suppose that these buildings represent the development of technology in Korean modern architecture. By the detailed analysis of these buildings, we can arrive at a conclusion as such; During the years 1955-1999, there existed a great changement in the eighties. We can find this fact very well in the domain of structural system and curtain wall system. In large spatial structures, the structural-system of shell and steel truss dome was replaced by that of space frame, space truss and cable truss with membrane. In tall building, the structural system of rigid frame and shear wall was replaced by tubular system, core and outrigger system. Korean architects introduced the aluminum curtain wall in the sixties, but its low technological level caused many problems in reality. Therefore, precast concrete curtain wall appeared from seventies as the main method for an outer wall in tall building. With the augmentation of height after 1980, PC curtain wall was replaced by the aluminum curtain wall of unit type and structural glass wall system. These systems help to stress the transparency in a tall building.

• Wind and Structures
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• 제14권6호
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• pp.559-582
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• 2011

This paper presents an integrated wind-induced dynamic analysis and computer-based design optimization technique for minimizing the structural cost of general tall buildings subject to static and dynamic serviceability design criteria. Once the wind-induced dynamic response of a tall building structure is accurately determined and the optimal serviceability design problem is explicitly formulated, a rigorously derived Optimality Criteria (OC) method is to be developed to achieve the optimal distribution of element stiffness of the structural system satisfying the wind-induced drift and acceleration design constraints. The effectiveness and practicality of the optimal design technique are illustrated by a full-scale 60-story building with complex 3D mode shapes. Both peak resultant acceleration criteria and frequency dependent modal acceleration criteria are considered and their influences on the optimization results are highlighted. Results have shown that the use of various acceleration criteria has different implications in the habitability evaluations and subsequently different optimal design solutions. The computer based optimization technique provides a powerful tool for the lateral drift and occupant comfort design of tall building structures.

• Earthquakes and Structures
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• 제21권5호
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• pp.515-530
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• 2021

In a tall reinforced concrete (RC) core wall system subjected to strong ground motions, inelastic behavior near the base as well as mid-height of the wall is possible. Generally, the formation of plastic hinge in a core wall system may lead to extensive damage and significant repairing cost. A new configuration of core structures consisting of buckling restrained braced frames (BRBFs) and RC walls is an interesting idea in tall building seismic design. This concept can be used in the plan configuration of tall core wall systems. In this study, tall buildings with different configurations of combined core systems were designed and analyzed. Nonlinear time history analysis at severe earthquake level was performed and the results were compared for different configurations. The results demonstrate that using enough BRBFs can reduce the large curvature ductility demand at the base and mid-height of RC core wall systems and also can reduce the maximum inter-story drift ratio. For a better investigation of the structural behavior, the probabilistic approach can lead to in-depth insight. Therefore, incremental dynamic analysis (IDA) curves were calculated to assess the performance. Fragility curves at different limit states were then extracted and compared. Mean IDA curves demonstrate better behavior for a combined system, compared with conventional RC core wall systems. Collapse margin ratio for a RC core wall only system and RC core with enough BRBFs were almost 1.05 and 1.92 respectively. Therefore, it appears that using one RC core wall combined with enough BRBF core is an effective idea to achieve more confidence against tall building collapse and the results demonstrated the potential of the proposed system.

• Wind and Structures
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• 제9권6호
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• pp.473-492
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• 2006

This paper presents numerical results of pedestrian-level wind environment around the base of a row of tall buildings by CFD. Four configurations of building arrangement are computed including a single square tall building. Computed results of pedestrian-level wind flow patterns and wind speeds are compared to previous wind tunnel measurement data to enable an assessment of CFD predictions. The CFD model uses the finite-volume method with RNG $k-{\varepsilon}$ model for turbulence closure. It is found that the numerical results can reproduce key features of pedestrian-level wind environment such as corner streams around corners of upwind building, sheltered zones behind buildings and channeled high-speed flow through a building gap. However, there are some differences between CFD results and wind tunnel data in the wind speed distribution and locations of highest wind speeds inside the corner streams. In locations of high ground-level wind speeds, CFD values match wind tunnel data within ${\pm}10%$.