• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 가을 학술발표회 논문집
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• pp.267-272
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• 1993

Currently about 60 contries in the world require earthquake resistant structural design in case of multistory building constructions. In these cases the equivalent lateral force procedure is commonly adopted because of its simplicity and convenience. This procedure, however, is developed based mainly on the first vibration mode response of building structure. The dynamic analysis of tall building shows that the effect of higher modes of vibration on the response of the building can not be neglected. In this paper, the effect of higher modes of vibration on seismic response is evaluated through modal analysis of tall building structures. On the basis of evaluation results, an improved procedure is to be proposed for the extended application of the equivalent lateral force procedure.

• Wind and Structures
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• 제36권2호
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• pp.105-120
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• 2023

The present study is performed to find the effect of corner recession on a square plan-shaped tall building. A series of numerical simulations have been carried out to find the two orthogonal wind force coefficients on various model configurations using Computational Fluid Dynamics (CFD). Numerical analyses are performed by using ANSYS-CFX (k-ℇ turbulence model) considering the length scale of 1:300. The study is performed for 0° to 360° wind angle of attack. The CFD data thus generated is utilised to fit parametric equations to predict alongwind and crosswind force coefficients, C_fx and C_fy. The precision of the parametric equations is validated by employing a wind tunnel study for the 40% corner recession model, and an excellent match is observed. Upon satisfactory validation, the parametric equations are further used to carry out multiobjective optimization considering two orthogonal force coefficients. Pareto optimal design results are presented to propose suitable percentages of corner recession for the study building. The optimization is based on reducing the alongwind and crosswind forces simultaneously to enhance the aerodynamic performance of the building.

• 국제초고층학회논문집
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• 제12권2호
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• pp.153-162
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• 2023

Achieving sustainable spaces is one of the emerging trends of tall buildings regarding their significant impacts on the cities. Reducing energy consumption and material using is investigated as a widely used approach to achieve more efficient tall buildings. Defining more efficient geometries and form modifications have been adopted for this goal. In this paper the effect of plan shape and diagrid angle on structural efficiency of diagrid tall buildings have been studied. A parametric workbench is applied to generate and analyze models. The goal is to find effective form parameters resulting in more efficient forms. Respectively, all models were generated in Rhino/grasshopper architecturally and analyzed by a finite element plug-in structurally. Based on the results, steeper angles almost cause more displacements and needs to be more stiffened. it can be seen almost more sided models need less weight for the structures and it could lead to more efficient forms.

• Wind and Structures
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• 제18권4호
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• pp.443-456
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• 2014

A popular modern architectural form for tall buildings is two (or more) towers which are structurally linked through such features as a shared podium or sky-bridges. The fundamental features of the wind loading and the structural links of such buildings can be studied by measuring load components on the individual unlinked towers along with their correlations. This paper describes application of dual high frequency force balance (DHFFB) in a wind tunnel study of the base wind loading exerted on generic tall twin buildings in close proximity. Light models of two identical generic tall buildings of square plan were mounted on DHFFB and the base wind loading exerted on the buildings was simultaneously acquired. The effects of the relative positions of the buildings on the correlations and coherences involving loading components on each building and on the two buildings were investigated. For some relative positions, the effects of the building proximity on the wind loading were significant and the loading was markedly different from that exerted on single buildings. In addition, the correlations between the loadings on the two buildings were high. These effects have potential to significantly impact, for example, the modally-coupled resonant responses of the buildings to the aerodynamic excitations. The presented results were not meant to be recommended for direct application in wind resistant design of tall twin buildings. They were intended to show that wind loading on tall buildings in close proximity is significantly different from that on single buildings and that it can be conveniently mapped using DHFFB.

• 국제초고층학회논문집
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• 제1권1호
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• pp.53-59
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• 2012

With the rise in CPU power and the generalization and popularity of computers, engineering practice also changed from hand calculations to 3D computer models, from elastic linear analysis to 3D nonlinear static analysis and 3D nonlinear transient dynamic analysis. Thanks to holistic design approach and current trends in freeform and contemporary architecture, BIM concept is no longer a dream but also a reality. BIM is not just providing a media for better co-ordination but also to shorten the round-the-clock time in updating models to match with other professional disciplines. With the parametric modeling tools, structural information is also linked with BIM system and quickly produces analysis and design results from checking to fabrication. This paper presents a new framework which not just linked the BIM system by means of parametric mean but also create and produce connection FE model and fabrication drawings etc. This framework will facilitate structural engineers to produce well co-ordinate, optimized and safe structures.

• Wind and Structures
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• 제32권5호
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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.

• Wind and Structures
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• 제29권2호
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• pp.139-147
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• 2019

One of the most important factors in tall buildings design in urban spaces is wind. The present study aims to investigate the aerodynamic behavior in the square and triangular footprint forms through aerodynamic modifications including rounded corners, chamfered corners and recessed corners in order to reduce the length of tall buildings wake region. The method used was similar to wind tunnel numerical simulation conducted on 16 building models through Autodesk Flow Design 2014 software. The findings revealed that in order to design tall 50 story buildings with a height of about 150 meters, the model in triangular footprint with aerodynamic modification of chamfered corner facing wind direction came out to have the best aerodynamic behavior comparing the other models. In comparison to the related reference model (i.e., the triangular footprint with sharp corners and no aerodynamic modification), it could reduce the length of the wake region about 50% in general. Also, the model with square footprint and aerodynamic modification of chamfered corner with the corner facing the wind could present favorable aerodynamic behavior comparing the other models of the same cluster. In comparison to the related reference model (i.e., the square footprint with sharp corners and no aerodynamic modification), it could decrease the wake region up to 30% lengthwise.

• 국제초고층학회논문집
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• 제7권3호
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• pp.215-221
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• 2018

Buckling-Restrained Braces (BRBs) have been widely applied to tall buildings in seismic areas in the world. In this paper the author summarizes representative types of BRB compositions and shows two cases of special applications of BRBs. In the first case, BRB diagonals for tall building were used to provide stable cyclic nonlinear hysteresis and also used to limit forces generated at columns, connections and walls. The top outriggers are pre-loaded by jacks to resolve long-term differential shortenings between the concrete core wall and concrete-filled steel box columns. The second case is the retrofit work for a communication tower by replacing the insufficiently strong members with BRBs in Japan.

• 한국공간구조학회논문집
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• 제16권3호
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• pp.107-115
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• 2016

In recent years, an outrigger damper system has been proposed to reduce dynamic responses of tall buildings. However, a study on outrigger damper system is still in its early stages. In this study, time history analysis was performed to investigate the dynamic response control performance of outrigger damper. To do this, a actual scale 3-dimensional tall building model with outrigger damper system has been developed. El Centro earthquake was applied as an earthquake excitation. The control performance of the outrigger damper system was evaluated by varying stiffness and damping values. Analysis results, on the top floor displacement response to the earthquake load, was greatly effected by damping value. And acceleration response greatly was effected by stiffness value of damper system. Therefore, it is necessary to select that proper stiffness and damping values of the outrigger damper system.

• Structural Engineering and Mechanics
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• 제23권6호
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• pp.675-689
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• 2006

In structural analysis of tall buildings the traditional primary loading analysis approach that assumes all the loads are simultaneously applied to the fully built structure has been shown to be unsuitable by many researches. The construction sequential analysis that reflects the fact of the level-by-level construction of tall buildings can provide more reliable results and has been used more and more. However, too much computational cost has prevented the construction sequential analysis from its application in CAD/CAE software for building structures, since such an approach needs to deal with systematic changing of resultant stiffness matrices following level-by-level construction. This paper firstly analyzes the characteristics of assembling and triangular factorization of the stiffness matrix in the finite element model of the construction sequential analysis, then presents a fast construction sequential analysis strategy and a corresponding step-by-step active column solver by means of improving the existing skyline solver. The new strategy avoids considerably repeated calculation by only working on the latest appended and modified part of resultant stiffness matrices in each construction level. Without any simplification, the strategy guarantees accuracy while efficiency is greatly enhanced. The numerical tests show that the proposed strategy can be implemented with high efficiency in practical engineering design.