• 한국강구조학회 논문집
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• 제20권4호
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• pp.505-517
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• 2008

휨지배 거동을 나타내는 세장한 이중강판합성벽의 비탄성 거동을 예측하기 위하여 비선형 수치해석 모델이 연구되었다. 수치해석의 편리를 위하여, 제안된 모델은 비교적 단순한 모델을 가지고 비탄성 거동을 근사적으로 예측할 수 있는 거시적 모델로 개발되었다. 휨지배 거동을 나타내는 벽체에 대해서는 다중평행요소 모델이 사용되었으며, 깊은 연결보의 전단거동을 위하여 X형 대각요소 모델이 사용되었다. 각 요소의 주기거동을 예측하기 위하여 콘크리트 및 강판 요소에 대한 간략화된 일축의 주기모델을 제안하였다. 제안된 해석모델은 1자형 및 T형 단일벽과 병렬벽에 적용하였으며, 그 결과는 기존의 실험결과와 비교되었다.

• Wind and Structures
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• 제38권1호
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• pp.15-42
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• 2024

A flexible-base coupled-two-beam (CTB) discrete model with equivalent tuned mass dampers is used to assess the effect of soil-structure interaction (SSI) and different types of lateral resisting systems on the design of passive dynamic absorbers (PDAs) under the action of along-wind and across-wind loads due to vortex shedding. A total of five different PDAs are considered in this study: (1) tuned mass damper (TMD), (2) circular tuned sloshing damper (C-TSD), (3) rectangular tuned sloshing damper (R-TSD), (4) two-way liquid damper (TWLD) and (5) pendulum tuned mass damper (PTMD). By modifying the non-dimensional lateral stiffness ratio, the CTB model can consider lateral deformations varying from those of a flexural cantilever beam to those of a shear cantilever beam. The Monte Carlo simulation method was used to generate along-wind and across-wind loads correlated along the height of a real shear wall-frame building, which has similar fundamental periods of vibration and different modes of lateral deformation in the xz and yz planes, respectively. Ambient vibration tests were conducted on the building to identify its real lateral behavior and thus choose the most suitable parameters for the CTB model. Both alongwind and across-wind responses of the 144-meter-tall building were computed considering four soil types (hard rock, dense soil, stiff soil and soft soil) and a single PDA on its top, that is, 96 time-history analyses were carried out to assess the effect of SSI and lateral resisting system on the PDAs design. Based on the parametric analyses, the response significantly increases as the soil flexibility increases for both type of lateral wind loads, particularly for flexural-type deformations. The results show a great effectiveness of PDAs in controlling across-wind peak displacements and both along-wind and across-wind RMS accelerations, on the contrary, PDAs were ineffective in controlling along-wind peak displacements on all soil types and different kind of lateral deformation. Generally speaking, the maximum possible value of the PDA mass efficiency index increases as the soil flexibility increases, on the contrary, it decreases as the non-dimensional lateral stiffness ratio of the building increases; therefore, there is a significant increase of the vibration control effectiveness of PDAs for lateral flexural-type deformations on soft soils.

• 콘크리트학회논문집
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• 제27권6호
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• pp.661-668
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• 2015

병렬전단벽시스템은 횡력저항에 있어서 효율적인 구조시스템이지만, 각 독립벽체를 연결하는 연결보의 복잡한 철근상세로 인해 시공상의 어려움이 있다. ACI-318에서는 개선된 철근상세를 제안했지만, 이 또한 과도한 횡보강근으로 인해 대각철근의 중심부의 철근 배근 혼잡으로 인해 현장 적용에 어려움이 따른다. 본 연구에서는 프리캐스트를 통하여 철근 배근 오차 및 콘크리트 품질 등의 저하를 줄이고 ACI 318-11의 개선된 상세에 따른 기준 실험체와 일반대각철근을 묶음대각철근으로 대체한 철근콘크리트 연결보의 이력거동을 비교 평가하였다. 그 결과, 묶음대각철근을 적용한 실험체는 현행기준에 따른 연결보와 비교하여 유사한 이력거동을 나타냈고, 더 우수한 에너지소산능력을 나타냈다. 묶음대각철근을 적용한 철근콘크리트 연결보가 현행기준에 따르는 연결보를 대체하여 현장적용이 가능할 것으로 판단된다.

• Coupled systems mechanics
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• 제8권3호
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• pp.199-218
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• 2019

This paper studies the forced vibration of the hydro-elastic system consisting of the anisotropic (orthotropic) plate, compressible viscous fluid and rigid wall within the scope of the exact equations and relations of elastodynamics for anisotropic bodies for describing of the plate motion, and with utilizing the linearized exact Navier-Stokes equations for describing of the fluid flow. For solution of the corresponding boundary value problem it is employed time-harmonic presentation of the sought values with respect to time and the Fourier transform with respect to the space coordinate on the coordinate axis directed along the plate length. Numerical results on the pressure acting on the interface plane between the plate and fluid are presented and discussed. The main aim in this discussion is focused on the study of the influence of the plate material anisotropy on the frequency response of the mentioned pressure. In particular, it is established that under fixed values of the shear modulus of the plate material a decrease in the values of the modulus of elasticity of the plate material in the direction of plate length causes to increase of the absolute values of the interface pressure. The numerical results are presented not only for the viscous fluid case but also for the inviscid fluid case.

• 콘크리트학회논문집
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• 제23권5호
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• pp.569-579
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• 2011

주기하중을 받는 철근콘크리트 벽체는 형상비, 배근상세, 재하 조건 등에 따라 복잡한 비탄성 거동을 보인다. 이 연구에서는 벽체의 휨-압축 거동과 전단거동을 간편하게 고려할 수 있는 거시 요소를 이용한 비선형 해석 방법을 개발하였다. 철근콘크리트 벽체의 휨-압축 거동 및 전단거동은 각각 길이 방향 및 대각 방향 1축 요소로 이상화된다. 1축 요소는 콘크리트와 철근으로 구성되고, 비선형 재료 모델로서 1축 상태에서 반복하중을 받는 콘크리트와 철근의 주기거동 모델을 사용한다. 검증을 위하여 제안된 방법을 사용하여 주기하중을 받는 철근콘크리트 단일벽 및 병렬벽의 비선형 해석을 수행하였다. 그 결과 제안된 방법은 휨-압축 거동이 지배적인 세장한 벽체와 전단거동이 지배적인 낮은 벽체의 주기거동을 정확하게 예측하였다. 제안된 거시 해석 모델은 모델링이 편리하고 수치해석의 안정성이 우수하므로, 전단벽 및 코어벽이 사용된 건물의 비선형 해석을 위한 범용 프로그램으로 개발이 용이할 것으로 판단된다.

• Coupled systems mechanics
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• 제11권4호
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• pp.315-333
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• 2022

Fluid-Structure Interaction (FSI) modeling is highly effective to reveal deformations, fatigue failures, and stresses on a solid domain caused by the fluid flow. Mechanical properties of the solid structures and the thermophysical properties of fluids can change under different operating conditions. In this study, we investigated the interaction of [45/-45]₂ wounded composite tubes with the fluid flows suddenly pressurized to 5 Bar, 10 Bar, and 15 Bar at the ambient temperatures of 24℃, 66℃, and 82℃, respectively. Numerical analyzes were performed under each temperature and pressure condition and the results were compared depending on the time in a period and along the length of the tube. The main purpose of this study is to present the effects of the variations in fluid characteristics by temperature and pressure on the structural response. The variation of the thermophysical properties of the fluid directly affects the deformation and stress in the material due to the Wall Shear Stress (WSS) generated by the fluid flow. The increase or decrease in WSS directly affected the deformations. Results show that the increase in deformation is more than 50% between 5 Bar and 10 Bar for the same operating condition and it is more than 100% between 5 Bar and 15 Bar by the increase in pressure, as expected in terms of the solid mechanics. In the case of the increase in the temperature of fluid and ambient, the WSS and Von Mises stress decrease while the slight increases of deformations take place on the tube. On the other hand, two-way FSI modeling is needed to observe the effects of hydraulic shock and developing flow on the structural response of composite tubes.

• Earthquakes and Structures
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• 제1권1호
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• pp.1-19
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• 2010

It has been known that one-dimensional rod theory is very effective as a simplified analytical approach to large scale or complicated structures such as high-rise buildings, in preliminary design stages. It replaces an original structure by a one-dimensional rod which has an equivalent stiffness in terms of global properties. If the structure is composed of distinct constituents of different stiffness such as coupled walls with opening, structural behavior is significantly governed by the local variation of stiffness. This paper proposes an extended version of the rod theory which accounts for the two-dimensional local variation of structural stiffness; viz, variation in the transverse direction as well as longitudinal stiffness distribution. The governing equation for the two-dimensional rod theory is formulated from Hamilton's principle by making use of a displacement function which satisfies continuity conditions across the boundary between the distinct structural components in the transverse direction. Validity of the proposed theory is confirmed by comparison with numerical results of computational tools in the cases of static, free vibration and forced vibration problems for various structures.

• 한국지진공학회논문집
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• 제21권6호
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• pp.303-310
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• 2017

The coupled shear wall system with coupling beams is an efficient structural system for high-rise buildings because it can provide excellent ductility and energy dissipation to the buildings. The objective of this study is to simulate the hysteretic behavior of diagonally reinforced concrete coupling beams including pinching and cyclic deteriorations in strength and stiffness using a numerical model. For this purpose, coupling beams are modeled with an elastic beam element and plastic spring element placed at the beam ends. Parameters for the analytical model was calibrated based on the test results of 6 specimens for diagonally reinforced concrete coupling beams. The analytical model with calibrated model parameters is verified by comparing the hysteretic curves obtained from analysis and experimental tests.

• 소음진동
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• 제5권2호
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• pp.225-234
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• 1995

In this study, first, transformation process of damping ratios, whose are evaluated in active control analysis, into damping matrix resulting from installed viscous dampers is illustrated. Then, a method is followed to maximize the effect of response reduction, which leads to optimum locations and size of viscous dampers using sensitivity analysis. Highly coupled nonlinearity between damping ratios and dampers makes it hard to find the optimal size of dampers. Therefore, the nonlinearity is transformed to linear problem with small increments of damping ratios and the size of dampers can be found. However, there are many cases for the size of dampers satisfying the small increment of damping ratios, so it is necessary to select minimum size using optimization technique. To determine optimum locations of dampers, dampers are assumed to be installed between the different stories and their locations are selected corresponding corresponding to the degree of damping size. Numerical examples for the frame structure and the shear wall structure show that optimum locations and size of dampers are different form each other depending on the characteristics of modal responses of the structures. The proposed method in this study can be applied to get optimum locations of active controller in the active control.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.129-132
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• 2008

병렬 전단벽구조의 이상적인 거동을 만족시키기 위한 대안의 하나로 철근콘크리트커 플링보에 전단 성능이 우수한 철골 플레이트를 매립하는 방안이 제시되었다. Lam의 연구에 의하면 플레이트를 보강한 시험체가 기존의 철근 콘크리트 커플링보에 비하여 내진성능이 매우 우수한 것을 제시하고 있다. 철골 플레이트 커플링보는 철골 부재와 철근콘크리트 부재로 구성된 합성구조이다. 따라서 철골 부재는 강구조 설계 기준에 의해 설계하고, 철근콘크리트 부재는 철근콘크리트 설계기 준에 의해 설계하여 중첩시키는 방법으로 설계한다. 그러나 아직까지 합성구조에 대한 설계 기준이 마련되어 있지 않은 이유로 본연구에서는 실무에서 쓰이는 기준식의 평가를 통하여 철골 커플링보의 안전성을 검토하고자 한다. 기존 연구의 데이터를 통계학적 분석방법을 이용하여, ACI 기준식과 BS 기준식을 각각 검증하였다. 분석 결과 철근콘크리트의 전단력과 철골 플레이트의 전단력을 중첩하여 계산하는 철골 플레이트 커플링보에 대한 현재의 실무에서의 설계방법은 기존의 실험결과와 비교하면 적절한 설계방법으로 판단된다.