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.

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.

This paper deals with the numerical model of a bracing-friction damper system and its deployment using the optimal slip load distribution for the seismic retrofitting of a damaged building. The Slotted Bolted Connection (SBC) type friction damper system was tested to investigate its energy dissipation characteristic. Test results coincided with the numerical ones using the conventional model of a bracing-friction damper system. The placement of this device was numerically explored to apply it to the assumed damaged-building and to evaluate its efficiency. It was found by distributing the slip load that minimizes the given performance indicies based on structural response. Numerical results for the damaged building retrofitted with this slip load distribution showed that the seismic design of the bracing-friction damper system under consideration is effective for the structural response reduction.

In this paper, excitation systems using linear mass shaker (LMS) and active tuned mass damper (ATMD) are presented in order to simulate the wind induced responses of a building structure. The actuator force for the excitation systems is calculated by using the inverse transfer function of a target structural response to the actuator. Filter and envelop function are used such that the error between the wind and actuator induced responses is minimized by preventing the actuator from exciting unexpected modal response and initial transient response. The analyses results from a 76-story benchmark building problem in which wind load obtained by wind tunnel test is given, indicate that the excitation system installed at a specific floor can approximately embody the structural responses induced by the wind load applied to each floor of the structure. The excitation system designed by the proposed method can be effectively used for evaluating the wind response characteristics of a practical building structure and for obtaining an accurate analytical model of the building under wind load.

본 연구에서는 건물모델만을 물리적인 실험체로 이용하여 동적 지반강성을 갖는 지반-구조물계의 동적거동을 모사하기 위한 하이브리드 진동대 실험법을 제안하고 이를 실험적으로 검증하였다. 본 연구에서 제안되는 실험방법은 상부구조물과 진동대의 가속도를 계측하여 진동대 제어기로 피드백하고, 전체 지반-구조물계의 동적거동을 묘사하기 위해 요구되는 기초부분의 절대가속도 응답(가속도 피드백 방법) 또는 절대속도 응답(속도 피드백 방법)을 계산하여 진동대를 구동시키는 방법이다. 지반부분을 계산하기 위해서 이론적인 동적지반강성을 제안방법에 따라서 다르게 근사화하여 진동대 제어기에 반영함으로써 실험을 수행하였다. 기초 고정계 모델에 대한 실험으로부터 계측된 응답과 본 논문에서 가정한 지반-구조물 계에 대한 실험으로부터 측정된 응답을 비교하고, 진동대 제어기에 반영한 동적지반강성과 실험데이터를 이용하여 식별된 동적지반강성을 비교함으로써 본 논문에서 제안된 실험방법의 유효성을 검증하였다.

Forced vibration testing is important for correlating the mathematical model of a structure with the realone and for evaluating the performance of the real structure. There exist various techniques available for evaluating the seismic performance using dynamic and static measurements. In this paper, full scale forced vibration tests simulating earthquake response are implemented by using a hybrid mass damper. The finite element(FE) model of the structure was analytically constructed using ANSYS and the model was updated using the results experimentally measured by the forced vibration test. System identification of real-scaled 5 story building structure which is located in UNISON INC. is conducted on the updated FE model.

It is considered that taking off such thought that our country is safe from earthquakes, the development of technologies to prevent secondary calamities due to seismic loads such as a fire and gas explosion is urgently required. The objective of this study is to establish the level of indices for determining the danger level of structures, which can be applied to a real-time seismic monitoring to minimize auxiliary damages of structures due to earthquakes. First, the cumulative absolute velocity (CAV) closely related to the concept of averaged velocity of a certain earthquake wave and the spectral intensity (SI) values based on the velocity response spectrum are addressed to specify a certain level of indices for a real-time seismic monitoring. Then, the CAV and SI values are calculated with the artificial seismic waves that are produced based on the design response spectrum of a structure specified in the seismic criteria of KBC 2005. Finally, the early warning, shut-down of facilities and escape stages are proposed by determining the level of indices which are compared with the results of existing studies.

본 논문에서는, 동조액체감쇠기(이하 TLD)만을 실험적 부분구조로 이용하여 TLD가 설치된 건축구조물의 지진 응답 제어효과를 평가하기 위한 실시간 하이브리드 실험법을 제안하고 진동대 실험을 통해 실험적으로 규명한다. 제안된 실험법에서, TLD가 설치된 전체구조물은 상부의 TLD와 하부의 구조물 부분으로 각각 실험적 그리고 수치해석적 부분구조로 나누어진다. 이때 부분구조 사이의 경계면에서 작용하는 하중 또는, TLD에 의한 제어력은 진동대에 설치된 전단형 로드셀에 의해 계측되며 진동대는, 계측된 경계면에서의 제어력이 상부에 작용하고 또한 동시에 기초에 지진하중이 작용하는 수치해석적 부분구조로부터 계산된 응답으로, 상부에 설치된 TLD를 가진하게 된다. 제안된 실험법에 의한 결과와 TLD와 건물모델 모두를 제작하여 실험하는 기존의 방법에 의한 실험 결과들은 서로 잘 일치하며, 이로써 본 논문에서 제안된 실험법을 이용하여 TLD의 제어성능을 손쉽게 평가 할 수 있음을 알 수 있다.

가섭선 및 애자가 연결되어 있는 복잡한 구조물인 송전철탑의 3차원 모델링을 통하여 동특성을 파악하고, 풍하중에 대한 응답 특성을 정적, 동적 및 좌굴 해석을 가섭선의 절단 유무에 따라 분석하였다. 우선, 고유치해석을 통해, 송전철탑이라는 구조시스템이 일반 건축물과는 달리 극소수의 저차 모드가 구조물의 동적 거동을 좌우하지 않고, 상대적으로 많은 모드들이 동적 거동에 기여한다는 것을 확인하였다. 두 번째로, 정적 해석과 좌굴 해석을 통해, 대상 구조물이 정적인 개념의 풍하중에 대해서 구조적으로 안전하고 좌굴에 대해서도 충분한 안전율을 확보하고 있음을 확인하였다 그러나, 모든 가섭선이 단절되는 극단적인 경우에는 안전율이 상당히 낮아졌으며 이러한 경우에 구조물의 붕괴 및 전도를 방지할 대책에 대한 검토가 필요하다고 사료된다 마지막으로, 풍하중의 시간에 따른 변화를 고려한 동적해석을 통해, 풍하중의 동적 변동성분이 구조물의 응답을 증가시키고 있음을 확인하였다.

Seismic control performance of MR dampers, which have severe nonlinearity, is different with respect to the dynamic characteristics of earthquake excitations such as magnitude and frequency contents. In this study, effects of excitation characteristics on the equivalent linear system represented by an equivalent damping ratio for single-degree-of-freedom (SDOF) systems with a MR damper are investigated through numerical analysis for various natural frequencies of the structures and design parameters of the MR damper. In addition, to implement the an equivalent linearization procedure considering non-stationarity and frequency contents of the earthquake excitation, seismic response reduction factors for artificial earthquake ground motions are proposed using regression analysis of the linear structural responses. Analysis results show that the relative magnitude of the excitation compared to the friction force of the MR damper and frequency contents of the excitation affect the equivalent damping ratio considerably, and appropriate combination of friction and damping produces additional damping effect