• Earthquakes and Structures
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• 제14권5호
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• pp.459-465
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• 2018

Reducing response of buildings during earthquakes by mass dampers, has been examined in many articles and books. Nowadays, many researchers are trying to realistically examine this type of dampers by new methods of performance. In this paper, for the better study of tuned mass damper (TMD), two schematic models are presented for a passive TMD with softening stiffness (softening TMD) and a passive TMD with hardening stiffness (hardening TMD). Then by modeling and analysis of the damper on a single degree of freedom (SDOF) structure and an 11-story steel building, the dampers performance was evaluated. State space was used for damper and structure modeling and to solve nonlinear equations, the Newton-Raphson method was used. The results show that when the structure is subjected to the Chi-Chi earthquake, response of the sixth floor in the system without TMD reduces 54.0% in comparison to the structure with softening TMD. This percentage of reduction for hardening TMD is 55.0%. Also for the Tabas earthquake, reduction in the RMS acceleration of the sixth floor in the system with hardening TMD is 96.2% more than the structure without TMD. This percentage of reduction for hardening TMD is 96.3%.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.492-499
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• 2004

The purpose of this paper is to present a design procedure of coulomb friction dampers for controlling elastic and inelastic responses of building structures. The equivalent damping and frequency increased by the friction damper are estimated using ATC-40 and ATC-55 procedures which provide equivalent linear system for bilinear one, and then a design formula to achieve target performance response level by friction damper is presented. It is identified that there exists error between the responses obtained by this formula and by performing nonlinear analysis and the features of the error vary according to the hardening ratio, yield strength ratio, and structural period. Equations for compensating this er개r are reposed based on the least square method, and the results from numerical analyses indicate that the error is significantly reduced, and the proposed formula can be used without much error for designing coulomb friction damper for retrofitting a structure showing elastic or inelastic behavior.

• Structural Engineering and Mechanics
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• 제66권2호
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• pp.161-172
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• 2018

The passive control of structures using a pendulum tuned mass damper has been extensively studied in the technical literature. As the frequency of the pendulum depends only on its length and the acceleration of gravity, to tune the frequency of the pendulum with that of the structure, the pendulum length is the only design variable. However, in many cases, the required length and the space necessary for its installation are not compatible with the design. In these cases, one can replace the classical pendulum by a virtual pendulum which consists of a mass moving over a curved surface, allowing thus for a greater flexibility in the absorber design, since the length of the pendulum becomes irrelevant and the shape of the curved surface can be optimized. A mathematical model for a building with a pendular tuned mass damper and a detailed parametric analysis is conducted to study the influence of this device on the nonlinear oscillations and stability of the main system under harmonic and seismic base excitation. In addition to the circular profiles, different curved surfaces with softening and hardening characteristics are analyzed. Also, the influence of impact on energy dissipation is considered. A detailed parametric analysis is presented showing that the proposed damper can not only reduce sharply the displacements, and consequently the internal forces in the main structure, but also the accelerations, increasing user comfort. A review of the relevant aspects is also presented.

• 한국지진공학회논문집
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• 제9권1호통권41호
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• pp.9-16
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• 2005

본 논문의 목적은 탄성과 비탄성 구조물의 지진응답제어를 위한 마찰감쇠기의 설계절차를 제시하는 것이다. ATC-40과 ATC-55를 이용하여 비탄성 구조물의 등가선형감쇠비와 등가선형주기를 구하였고, 이에 기초하여 목표 성능을 만족하기 위한 마찰감쇠기의 최대마찰력을 결정하는 식을 제시하였다. 이 식은 항복 전후 강성비와 요구되는 탄성강도에 대한 항복강도비, 그리고 구조물의 주기에 따라 비선형 수치해석과 오차가 발생한다. 수식에 의해 산출한 최대마찰력과 비선형 수치 해석에 의해 산출된 값과의 오차를 줄이기 위하여, 최소 제곱법을 사용하여 오차 보정식을 제시하였다. 수치해석결과는 제안된 보정식을 사용하면 탄성 및 비탄성 지진응답제어를 위한 마찰감쇠기의 설계를 합리적으로 수행할 수 있음을 보여준다

• 대한기계학회논문집A
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• 제20권1호
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• pp.127-134
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• 1996

In general, seismic isolators which are made of laminated rubber and shim plate have characteristics of complex hysteretic behavior. When shear deformation of the seismic isolator is small, the isolator hassimple hysteretic almost bi-linear behabior. But on large shear deformation hardening effects may occur. This paper proposes a moldeling method of the seimic isolator with modified hysteretic bi-linear model which can consider the hardening effects. From the results of the seismic analyses of the isolated system it is shown that the responses are singificantly reduced compared with those of the non-isolated system. The modified hysteretic bi-linear model of the isolator gives larger ZPA(zero period acceleration) than those of the simple hysteretic bi-linear model and the equivalunt spring-damper model.

• 한국지진공학회논문집
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• 제12권6호
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• pp.65-71
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• 2008

본 논문에서는 반복하중에 의한 반복 경화 및 연화 현상을 나타낼 수 있는 수정 IWAN 모델을 이용하여, 1차원 비선형 부지응답 해석프로그램(이하 KODSAP; Kaist One Dimensional Site-response Analysis Program)을 개발하였다. 개발된 프로그램은 지진하중 재하에 따른 지반의 반복경화 및 연화현상에 의한 부지응답 특성 변화를 재현할 수 있다. KODSAP을 이용하여 기반암 상부 40m인 모형지반의 반복경화 및 연화 정도, 지진가속도의 크기에 따른 부지응답특성 변화를 살펴 보았으며, 현재 실무에서 널리 적용되고 있는 등가선형, 비선형해석과 KODSAP 해석결과(지반의 반복경화 및 연화현상을 고려한)과의 차이점을 살펴 보았다.