• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.3
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• pp.85-92
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• 2015

Response spectra of a building are made with a SDOF system taking into account a first mode shape, even though higher modes may affect on the dynamic responses of a high-rise building. A soft soil layer under a building also affects on the responses of a building. In this study, seismic responses of a MDOF system were investigated to examine the effects of higher modes on the response of a tall building by comparing them with those of a SDOF system including the kinematic interaction effect. Study was performed using a pseudo 3D finite element program with seven bedrock earthquake records downloaded from the PEER database. Effects of higher modes on the seismic responses of a tall building were investigated for base shear force and base moment of a MDOF system including story shear forces and story moments. Study results show that higher modes of a MDOF system contribute to a reduction of base shear force up to 1/4-1/5 of KBC and base moment. The effect of higher modes is more significant on the base shear force than on the base moment. Maximum story shear force and moment occurred at the top part of a building rather than at a base in the cases of tall buildings differently from short buildings, and higher modes of a tall building affected on the base forces making them almost constant at the base. A soft soil layer also affects some on the base shear force of a high-rise building independently on the soft soil type, but a soft soil effect is prominent on the base moment.

• Computational Structural Engineering : An International Journal
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• v.1 no.1
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• pp.11-20
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• 2001

The paper describes the conceptual design, structural modelling and wind load analysis of tall buildings. The lateral stiffness of the building can be obtained economically through the interaction of core walls with peripheral frame tube and/or bundle of frame tubes and integrated design of the basement. The main structural components should be properly distributed such that the building will deflect mainly in the direction of the applied force without inducing significant response in other directions and twist. The cost effectiveness can be further enhanced through close consultation between architects and engineers at an early stage of conceptual design. Simplified structural modelling of the building and its response in three principal directions due to wind load are included. Effects of the two main structural components on the performances of a 70-story reinforced concrete building in terms of peak drift and maximum acceleration under wind load are discussed.

• Computational Structural Engineering
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• v.10 no.2
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• pp.203-211
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• 1997

In the design of tall building system, the wind loading can be more dominant factor than earthquake loading, and thus, it is important to check the stability and human comfort against wind. Experimental wind tunnel test is usually performed to predict wind behavior of a tall building, however, the test is not cost-effective in the preliminary stage for various structural models of tall building systems. In this regard, the study is focused on the numerical wind analysis of the tall building with and without tuned mass dampers based on the three dimensional model of wind loads and building behavior. As a numerical result, an asymmetrical 102-story tall building is presented to show the results of root mean squares of build responses with and without tuned mass dampers.

• Journal of Korean Association for Spatial Structures
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• v.13 no.1
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• pp.79-86
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• 2013

For most of recent tall buildings, one characteristic is that their building shapes vary with height such as taper and setback, and this implies that the distribution of their structural components may also vary with height. Because of these structural variations, although the sectional shapes of these buildings are symmetric, it is difficult to say whether or not they are structurally symmetric. The acceleration responses of structurally asymmetric tall buildings are larger than those of non-eccentric buildings, thus raising the possibility of problems during strong winds and typhoons. This paper describes wind tunnel tests carried out using building models with height variations and acceleration response analyses, and discusses the resulting response characteristics. For tapered and setback buildings, although the across-wind accelerations are larger than those of a square building, the total root-mean-square accelerations remain small because of smaller along-wind and torsional rms accelerations. And it was found that the effects of statistical couplings between along-wind force and other two forces are negligible.

• Wind and Structures
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• v.32 no.5
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• pp.405-421
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• 2021

To gain insight into the wind-induced safety concerns associated with attached tower cranes during the construction of super-tall buildings, a 606 m level frame-core tube super-tall building is selected to investigate the wind-induced vibration response and fragility of an outer-attached tower crane at all stages of construction. The wind velocity time history samples are artificially generated and used to perform dynamic response analyses of the crane to observe the effects of wind velocity and wind direction under its working and non-working resting state. The adverse effects of the relative displacement response at different connection supports are also identified. The wind-resistant fragility curves of the crane are obtained by introducing the concept of incremental dynamic analysis. The results from the investigation indicate that a large relative displacement between the supports can substantially amplify the response of the crane at high levels. Such an effect becomes more serious when the lifting arm is perpendicular to the plane of the connection supports. The flexibility of super-tall buildings should be considered in the design of outer-attached tower cranes, especially for anchorage systems. Fragility analysis can be used to specify the maximum appropriate height of the tower crane for each performance level.

• International Journal of High-Rise Buildings
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• v.8 no.4
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• pp.283-290
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• 2019

Corner cut, corner chamfered or a building shape change are adopted in the design of tall buildings to achieve aerodynamic superiority as well as response reduction. Kikuchi et.al pointed out that large negative peak external pressures can appear near the inside corner of set-back low rise buildings. It is therefore necessary to pay attention to facade design around steps in building surfaces. Peak wind pressures for corner cut or corner chamfered configurations are given in the AIJ code. However, they cannot be applied where there are many variations of vertical and horizontal steps. There has been no previous systematic research on peak wind pressures around steps in building surfaces. In this study, detailed phenomenon of peak wind pressures around steps in buildings are investigated focusing on vertical and horizontal distances from the building's corner.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.499-504
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• 2008

Recently, the problem controlling lateral drift is important in tall buildings for improvement in economic efficiency and habitability. But, the Outrigger System, general used for tall building in Korea, has weak points with the occupancy of special space and the long duration of works. The dampers are applied to actively control building's response by earthquake and wind load in these days. Accordingly, we analyze the effect of the drift control using various dampers to substitute for the Outrigger System as the efficient system in tall buildings.

• Wind and Structures
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• v.21 no.1
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• pp.63-84
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• 2015

The shape of a tall building has significant impact on wind force generation and wind-induced dynamic response. To study the effect of recessed cavities, wind excitations on a wind-tunnel model of an H-section tall building were compared with those on a square-section building model. Characteristics of the fluctuating wind pressures on the side faces of the two tall buildings and their role in the generation of crosswind forces on the buildings were investigated with the space-time statistical tool of proper orthogonal decomposition (POD). This paper also compares the use of different pressure data sets for POD analysis in situations where pressures on two different surfaces are responsible for the generation of a wind force. The first POD mode is found to dominate the generation of crosswind excitation on the buildings.

• Wind and Structures
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• v.37 no.3
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• pp.229-243
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• 2023

This study analyzes the response of a tall building with an H-shaped cross-section when subjected to wind loading generated by the same H-shape. As normative standards usually adopt regular geometries for determining the wind loading, this paper shows unpublished results which compares results of the dynamic response of H-shaped buildings with the response of simplified section buildings. Computational Fluid Dynamics (CFD) is employed to determine the steady wind load on the H-shaped building. The CFD models are validated by comparison with wind tunnel test data for the k-ε and k-ω models of turbulence. Transient wind loading is determined using the Synthetic Wind Method. A new methodology is presented that combines Stochastic and CFD methods. In addition, time-history dynamic structural analysis is performed using the HHT method for a period of 60 seconds on finite element models. First, the along-wind response is studied for wind speed variations. The wind speeds of 28, 36, 42, and 50 m/s at 0° case are considered. Subsequently, the dynamic response of the building is studied for wind loads at 0°, 45°, and 90° with a wind speed of 42 m/s, which approximates the point of resonance between gusts of wind and the structure. The response values associated with the first two directions for the H-shaped building are smaller than those for the R-shaped (Equivalent Rectangular Shape) one. However, the displacements of the H-shaped building associated with the latter wind load are larger.

• Wind and Structures
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• v.18 no.4
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• pp.391-422
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• 2014

The high frequency force balance (HFFB) technique provides convenient measurements of integrated forces on rigid building models in terms of base bending moments and torque and/or base shear forces. These base moments or forces are then used to approximately estimate the generalized forces of building fundamental modes with mode shape corrections. This paper presents an analysis framework for coupled dynamic response of tall buildings with HFFB technique. The empirical mode shape corrections for generalized forces with coupled mode shapes are validated using measurements of synchronous pressures on a square building surface from a wind tunnel. An alternative approach for estimating the mean and background response components directly using HFFB measurements without mode shape corrections is introduced with a discussion on higher mode contributions. The uncertainty in the mode shape corrections and its influence on predicted responses of buildings with both uncoupled and coupled modal shapes are examined. Furthermore, this paper presents a comparison of aerodynamic base moment spectra with available data sets for various tall building configurations. Finally, e-technology aspects in conjunction with HFFB technique such as web-based on-line analysis framework for buildings with uncoupled mode shapes used in NALD (NatHaz Aerodynamic Loads Database) is discussed, which facilitates the use of HFFB data for preliminary design stages of tall buildings subject to wind loads.