본 연구진은 최근 U자 형태인 액체댐퍼의 수직관을 다수의 셀(사각 기둥)로 나누어 셀 상부를 개폐함에 따라 다양한 고 유진동수를 쉽게 재현하는 새로운 멀티셀 액체댐퍼를 제시하였다. 이러한 댐퍼를 1층 건물 모형에 설치하여 진동대 실험을 수행하여 건물응답이 감소되는 것을 검증하였다. 64층의 풍응답인 가속도를 제어할 수 있도록 댐퍼를 설계하기 위하여 건 물을 1자유도계로 축소하였다. 가속도 기반 상사비인 1/20를 적용하여 1층 건물 모형과 새로운 댐퍼를 제작하였다. 설계 진 동수인 0.65Hz가 구현되도록 모형건물의 질량과 강성을 쉽게 조절할 수 있도록 탈부착식으로 제작하였다. 모형건물은 중량 을 부담하는 질량부와 하부에 스프링과 LM guide가 설치된 구동부로 나누어서 제작되었다. 18개의 셀을 가지는 액체댐퍼 를 제작하여 고유진동수 조절 범위가 0.65Hz～0.81Hz인 것을 파악하였다. 대형 진동대에 설치한 모형건물의 일방향 가진을 통하여 모형의 응답을 측정하고 모형상부에 멀티셀 액체댐퍼가 설치되었을 경우 모형의 응답을 측정하여 비교하였다. 진동 대 가속도를 입력과 모형건물의 가속도를 출력으로 하는 전달함수를 통해 결과를 나타내었다. 예상한 바와 같이 멀티셀 액 체댐퍼의 고유진동수를 건물의 진동수에 동조시켰을 경우 건물의 가속도 응답이 감소함을 알 수 있었다.

This study proposed simply design procedure of a single degree of freedom (SDOF) structure equipped with friction dampers. General method is suggested in order to reduce the structural seismic response by using friction dampers. The analysis model was transformed into an equivalent mass-spring-dashpot system by approximating nonlinear friction damping force with equivalent viscous damping force. A closed form solution for dynamic amplification factor (DAF) for steady-state response was derived by the energy balance equation. The equivalent damping ratio was defined by using DAF at natural frequency. The transfer function between input harmonic excitation and output structural response was obtained from the DAF, and the response reduction factor of the root mean square (RMS) for displacements without and with friction dampers was analytically determined. Using the proposed procedure the friction force required for satisfying given target response reduction factor was obtained. Mean response reduction factors matched well with the target values based on the dynamic analysis results. It is concluded that the proposed method is quite simple for the design of friction dampers to reduce seismic response of the structure.

This study proposed simply design procedure of a single degree of freedom (SDOF) structure equipped with friction dampers. General method is suggested in order to reduce the structural seismic response by using friction dampers. The analysis model was transformed into an equivalent mass-spring-dashpot system by approximating nonlinear friction damping force with equivalent viscous damping force. A closed form solution for dynamic amplification factor (DAF) for steady-state response was derived by the energy balance equation. The equivalent damping ratio was defined by using DAF at natural frequency. The transfer function between input harmonic excitation and output structural response was obtained from the DAF, and the response reduction factor of the root mean square (RMS) for displacements without and with friction dampers was analytically determined. Using the proposed procedure the friction force required for satisfying given target response reduction factor was obtained. Mean response reduction factors matched well with the target values based on the dynamic analysis results. It is concluded that the proposed method is quite simple for the design of friction dampers to reduce seismic response of the structure.

Heunginjimun as treasure No.1 is wooden structure of 2 story. This stucly presents an investigation on vibration characteristics of Heunginjimun in Seoul through ambient vibration test. The research team studied structural characteristics unlike general building and performed the test. Natural or environmental excitation as ambient vibration source is always present and hence the test implies a minimum interference with normal use of the structure. Natural frequencies, damping ratio and modes are identified and compared using two strategies, Frequency Domain Decomposition, Stochastic Subspace Identification techniques. The result shows that behavior and dynamic property of Heuninjimun.

Friction dampers using the flexural deformation of shear walls can be installed as coupling beam system between two adjacent walls of shear wall structures. To verify the seismic control performance of proposed friction dampers, numerical nonlinear analysis of shear walls governed by flexural behavior is conducted. Control effectiveness of shear walls connected by beams with the proposed dampers are compared for single shear wall with same flexural rigidity. Average responses of the shear walls with the dampers are found with seven scaled-downed earthquakes based on KBC 2005 design spectrum. Slip load is the most important design parameter. It is designed to be 5, 10, 20, 30, 60, 90% of total vertical shear force at damper location to prevent damper slip in specific stories. Nonlinear time-history analysis is conducted by using SeismoSturct analysis program. Seismic control performance of the dampers is evaluated for base shear, energy dissipation and top-floor displacement. Results show that the dampers are the most effective in reducing the responses when their total slip load is 30% of total vertical shear force.

This study deals with the design of a bi-directional liquid damper for a SDOF structure. Two dampers are usually needed to reduce wind-induced responses of tall structures since they are along and across wind ones. The proposed damper has the advantage of controlling both responses with a single damper. The damper shows dynamic behavior of both tuned liquid column damper (TLCD) and tuned sloshing damper (TSD) in the direction of two axes perpendicular with each other. This paper presents experimental verification to confirm its control performance. First, shaking table test is carried out to investigate reducing responses of a SDOF structure by the damper. Control performance of the damper is expressed by the transfer function from shaking table accelerations to SDOF structure ones. Testing results show that the damper reduced bi-directional responses of a SDOF structure. Also, it reduced torsion responses. It was confirmed from system identification results that damping ratio of a SDOF structure increased by the bi-directional liquid damper.

This paper presents an investigation on dynamic characteristics of Heunginjimun through both ambient vibration and impact hammer tests. Heunginjimun, treasure No. 1 in Seoul, Korea, is a traditional wooden structure. Ambient vibration test is performed and spectrum analysis of time history is carried out to identify dominant frequency contents of Heunginjimun. Impact hammer test is undertaken to find the natural frequency of Heunginjimun with frequency response functions and phase information. Test results show that natural frequencies are 1.lHz, l.5Hz, 3.2Hz and 4.2Hz in two principal axes. Natural frequencies obtained by the tests are used to find the lateral stiffness of Heunginjimun. Simple dynamic models for Heunginjimun are suggested based on the moment resistance from joint beams and the restoring force due to column rocking. Lateral stiffness is found with identified natural frequencies and simple dynamic models.

In this study, nonlinear dynamic characteristics of a tuned liquid column damper (TLCD) varying with the amplitude of excitation input are evaluated through shaking table tests and numerical model of a TLCD. The tuned mass damper (TMD) analogy of a TLCD is used to simplify the formulation, in which involves equivalent viscous damping of the inherent nonlinear damping term of a TLCD. The equivalent TMD model of a TLCD shows that the dynamic behavior of a TLCD is affected by the natural frequency, the damping ratio and the ratio of total liquid mass to the mass in horizontal column of a TLCD. Shaking table test is performed to obtain experimental transfer functions that describe the dynamic behavior of a TLCD specimen subjected to a harmonic loading with various excitation amplitudes. Transfer functions for various excitation amplitudes are measured from shaking table acceleration to both the liquid displacement within a TLCD container and the control force produced by a TLCD specimen. Also, the dissipation energy due to the inherent damping of a TLCD is measured from the shaking table test varying with excitation amplitude. The variation of design parameters of a TLCD according to the excitation amplitude is investigated by comparing the transfer functions obtained from the shaking table test to those derived from the TMD analogy of a TLCD. These results showed that both the natural frequency and the mass ratio of a TLCD are independent on the variation of excitation amplitude, while the damping ratio of a TLCD increases with larger excitation amplitude.

High-rise apartments of shear wall system are governed by flexural behavior like a cantilever beam. Installation of the damper-brace system in a structure governed by flexural behavior is not suitable. Because of relatively high lateral stiffness of the shear wall, a load is not concentrate on the brace and the brace cannot perform a role as a damping device. In this paper, a friction damper applying flexibility of shear wall is proposed in order to reduce the deformation of a structure. To evaluate performance of the proposed friction damper, nonlinear time history analysis is executed by SeismoStruct analysis program and MVLEM(Multi Vertical Linear Element Model) be used for simulating flexural behavior of the shear wall. It is found that control performance of the proposed friction damper is superior to one of a coupled wall with rigid beam. In conclusion, this study verified that the optimal control performance of the proposed friction damper is equal to 45% of the maximum shear force inducing in middle-floor beam with rigid beam.

The purpose of this study is to verify the transfer function of input acceleration and output control force based on linearizing a damping term of Tuned Liquid Column Damper(TLCD) with nonlinearity analytically. In addition, analysis is conducted for dynamic characteristics according to the design parameter such as section ratio of both vertical and horizontal column and the level of liquid in the vertical column which is used for tuning method. The dynamic characteristics is identified by the analysis for the natural frequency, damping ratio and effective mass ratio of TLCD and a shaking table test for the transfer function. The results indicates that the level of liquid and section ratio affect the characteristics of damping ratio and mass ratio. Damping and mass ratio increase as the section of vertical column of TLCD decreases due to turbulence in the elbow of TLCD.

High-rise apartments of shear wall system are governed by flexural behavior like a cantilever beam. Installation of the damper-brace system in a structure governed by flexural behavior is not suitable. Because of relatively high lateral stiffness of the shear wall, a load is not concentrate on the brace and the brace cannot perform a role as a damping device. In this paper, a friction damper applying flexibility of shear wall is proposed in order to reduce the deformation of a structure. To evaluate performance of the proposed friction damper, nonlinear time history analysis is executed by SeismoStruct analysis program and MVLEM(Multi Vertical Linear Element Model) be used for simulating flexural behavior of the shear wall. It is found that control performance of the proposed friction damper is superior to one of a coupled wall with rigid beam. In conclusion, this study verified that the optimal control performance of the proposed friction damper is equal to 45% of the maximum shear force inducing in middle-floor beam with rigid beam .

This paper proposes a tuned liquid column sloshing damper(TICSD) and its optimal design to mitigate bidirectional responses of building structures. The proposed damper acts as a liquid column vibration absorber (LCVA) and a tuned sloshing damper(TSD), respectively, in both principal axes of building structures. Optimum designs of the TLCSD addresses the minimizing in terms of live load, area and volume due to its installation, comparing to each installation with two dampers in two principal directions, respectively. Numerical results from optimum designs shows that the control robustness due to changes in the effective column length and the effective mass of the TLCSD superiors to that uses the head loss coefficient and damping nets in an existing liquid column vibration absorber(LCVA) and TSD. The TLCSD is designed according to the similarity laws of 76 story benchmark building model. Numerical model of the proposed TLCSD is derived based on the experimentally obtained transfer functions according to rotational angles.

본 연구에서는 동조질량감쇠기(TMD)와 동조액체 기둥감쇠기(TLCD)로 구성된 2방향 감쇠기의 제어성능을 실험적으로 검증하였다. 본 연구에 사용된 감쇠기는 한방향으로는 TMD로 거동하고, 다른 직교하는 방향에서는 TLCD로 거동하여 제어력이 발생하는 감쇠기이다. 우선, 제작된 감쇠기의 동적특성과 TMD와 TLCD에 의해 발생하는 제어력들의 연계효과를 조사하기 위한 진동대 실험을 수행하였다. 다음으로 이러한 실험결과를 바탕으로 감쇠기의 동적특성에 영향을 미치는 파라미터를 정량적으로 평가하였다. 본 연구에서 사용된 감쇠기가 입사각을 갖는 진동에 의해 가진될 때 TMD와 TLCD에 의해 연계된 제어력이 발생하는 것을 진동대 실험결과로부터 확인하였다. 또한, 감쇠기가 건축물의 2방향 응답제어에도 효과적으로 사용될 수 있음을 확인하였다.

실시간 하이브리드 실험법(real-time hybrid testing method)은 구조물의 수치해석부와 실험부 부분구조를 운동방정식으로 통합하여 실시 간으로 동시에 계산과 실험을 수행하는 방법이다 본 연구는 실시간 하이브리드 실험법을 사용하여 수동 및 준능동 MR감쇠기가 설치된 건축구조물의 내진성능을 정량적으로 평가한다. 건물 모델은 실물 크기 5층 건물을 강제진동실험 결과를 통해 식별한 수치모델로 사용하였고, MR감쇠기는 실험적 부분구조르 UTM에 설치되었다. 본 연구에서 수행되는 실시간 하이브리드 실험은 사인파 및 지진파 가진을 통하여 얻은 결과와 전류에 따른 MR감쇠기의 제어력을 이용하여 얻은 Bouc-Wen모델을 사용하여 얻은 해석모델과 일치함으로 그 유효성을 입증하였다. 또한 예비연구로써 구조물의 응답을 최적으로 제어하기 위한 clipped-optimal 제어알고리즘과 modulated homogeneous friction 준능동 제어알고리즘을 MR감쇠기에 적용하였다. 각 전류별 Bouc-Wen모델을 곡선맞춤하여 각각의 Bouc-Wen모델 파라미터를 식별하였으며 그 결과를 준능동 제어알고리즘 수치해석에 적용하였다. 또한 실시간 하이브리드 실험법을 이용한 준능동 제어 실험결과와 해석결과를 비교하여 준능동 제어알고리즘의 성능을 평가함에 있어 실시간 하이브리드 실험이 합리적임을 보여준다.

Real-time hybrid testing technique (RT-HYTT) is a structural dynamic testing method that the numerical calculation of the equations of motion of a structure and the experimental measurement of the reaction forces resulting from the application of this motion to the numerical structure are simultaneously implemented in real time. In this paper, structural control performance of the magneto-rheological (MR) damper installed in a real-scaled 5 story building is experimentally evaluated through real-time hybrid test method. In this method, a numerical substructure is based on a structural model identified from the forced vibration testing results of a real-story building, and an MR damper that is used as an experimental substructure is physically tested with a universal testing machine (UTM). In the test, load cell on the UTM measure the force necessary to attain the required story displacement and these structural reaction forces are returned to the computer for use in next time step calculation of a numerical structural model. Test results show that the higher level of control force generated by the Mr damper causes the lower level of controlled response of a structure.

A bi-axial tuned liquid mass damper(TLMD) was proposed and evaluated on its control performance. The proposed TLMD controls structural response in a specific one direction by using the liquid sloshing of TLCD. Also, the TLMD controls structural response in the other orthogonal direction by TMD behavior which mass consists of the container itself and liquid within container of TLCD installed on linear motion guides. Force-vibration tests on a real-sized structure with the TLMD were performed to verify its independent behavior in two orthogonal directions. Test results showed that the responses of a structure were considerably reduced by using the proposed TLMD and its usefulness for structural control in two orthogonal directions.

본 연구에서는 하나의 제어장치로 서로 직교하는 2방향의 건물응답을 동시에 제어할 수 있는 동조액체질량감쇠기(Tuned Liquid Mass Damper; TLMD)를 제안하고 제어성능을 실험적으로 검증하였다. 본 연구에서 제안된 TLMD는 한 방향으로는 동조액체기둥감쇠기(Tuned Liquid Column Damper; TLCD) 내부에 채워진 액체의 운동에너지를 이용하여 구조물의 응답을 제어하게 된다. 그리고, 다른 한 방향 즉 TLCD의 직각 방향으로는 LM guide(linear motion guide) 위에 놓인 TLCD 수조와 내부의 액체의 질량을 이용하여 동조질량감쇠기(Tuned Mass Damper; TMD)로 거동하게 함으로써 구조물의 응답을 감소시킨다. 이와 같은 TLMD의 양방향 독립거동 특성을 증명하기 위해 실물크기의 구조물에 설치하여 강제진동실험을 수행하였다. 실험결과, 양방향 모두 대상 구조물의 응답을 감소시키는 것을 확인하여 제안된 TLMD의 효용성을 검증하였다.

An experimental real-time hybrid method, which implements the wind response control of a building structure with only a two-way TLMD, is proposed and verified through a shaking table test. The building structure is divided into the upper experimental TLMD and the lower numerical structural part. The shaking table vibrates the TLMD with the response calculated from the numerical substructure，which is subjected to the excitations of the measured interface control force at its top story and an wind-load input at its base. The results show that the conventional method can be replaced by the proposed methodology with a simple installation and accuracy for evaluating the control performance of a TLMD

In this paper, a two-way tuned liquid mass damper(TLMD) using a tuned liquid column damper(TLCD) and a rubber-bearing-type tuned mass damper(TMD) was manufactured for controlling two-way direction acceleration responses of a high-rise building structure. The proposed controlling device behaves as a tuned liquid column damper in one direction and as a tuned mass damper in the other direction. In this study, Performance evaluation of the downscaled model is conducted. The results show that the two-way controllability is behaved independently each other and realscale TLMD applicable to the high-rise building can be designed.

본 논문에서 건축구조물의 풍응답 구현을 위한 선형질량가진기(linear mass shaker, LMS)와 능동동조질량감쇠기(active tuned mass damper, ATMD)를 이용한 가진시스템을 제안한다. 가진시스템을 위한 가진기의 힘은 가진기에 의한 구조물의 목표응답의 전달함수를 사용하여 계산된다. 필터와 포락곡선함수는 예측하지 못한 모드응답에 의한 가진과 초기 과도응답을 제거함으로써 실제 바람에 의한 응답과 가진기에 의한 응답의 오차를 최소화하기 위하여 사용되었다. 수치예제로는 풍동실험을 통한 풍하중이 주어진 76층 벤치마크 구조물을 이용하여 수치해석을 수행하였으며, 그 결과는 특정층에 설치된 가진시스템은 풍하중이 전층에 가진되었을 때의 응답을 근사하게 구현할 수 있음을 보여준다. 제안된 방법에 의해 설계된 가진시스템은 실제 건축구조물의 풍응답 특성을 평가하는데, 그리고 풍하중을 받는 건물의 정확한 수치모델을 얻는데 효과적으로 사용될 수 있다.