• Smart Structures and Systems
• /
• 제25권2호
• /
• pp.155-167
• /
• 2020

This paper demonstrates a real-time hybrid substructuring (RTHS) shake table test to evaluate the seismic performance of a base isolated building. Since RTHS involves a feedback loop in the test implementation, the frequency dependent magnitude and inherent time delay of the actuator dynamics can introduce inaccuracy and instability. The paper presents a robust stability and performance analysis method for the RTHS test. The robust stability method involves casting the actuator dynamics as a multiplicative uncertainty and applying the small gain theorem to derive the sufficient conditions for robust stability and performance. The attractive feature of this robust stability and performance analysis method is that it accommodates linearized modeled or measured frequency response functions for both the physical substructure and actuator dynamics. Significant experimental research has been conducted on base isolators and dampers toward developing high fidelity numerical models. Shake table testing, where the building superstructure is tested while the isolation layer is numerically modeled, can allow for a range of isolation strategies to be examined for a single shake table experiment. Further, recent concerns in base isolation for long period, long duration earthquakes necessitate adding damping at the isolation layer, which can allow higher frequency energy to be transmitted into the superstructure and can result in damage to structural and nonstructural components that can be difficult to numerically model and accurately predict. As such, physical testing of the superstructure while numerically modeling the isolation layer may be desired. The RTHS approach has been previously proposed for base isolated buildings, however, to date it has not been conducted on a base isolated structure isolated at the ground level and where the isolation layer itself is numerically simulated. This configuration provides multiple challenges in the RTHS stability associated with higher physical substructure frequencies and a low numerical to physical mass ratio. This paper demonstrates a base isolated RTHS test and the robust stability and performance analysis necessary to ensure the stability and accuracy. The tests consist of a scaled idealized 4-story superstructure building model placed directly onto a shake table and the isolation layer simulated in MATLAB/Simulink using a dSpace real-time controller.

• 한국음향학회지
• /
• 제15권5호
• /
• pp.99-106
• /
• 1996

컴프레서의 소음은 냉장고로부터 발생하는 전체 소음레벨중 높은 기여를 나타낸다. 그리고, 컴프레서로부터 방사되는 소음의 상당부분이 컴프레서 쉘의 진동에 의해 방사되는 소음이다. 본 연구에서는 컴프레서 쉘의 동특성을 규명하기 위하여 범용 구조해석 패키지인 MSC/NASTRAN을 이용하여 컴프레서 쉘을 여러 분계로 분리하여 해석한 뒤, 부분구조 합성법을 이용하여 전계의 동특성을 규명하였다. 그리고 각 분계의 변형 에너지와 운동에너지를 산정하여 각 분계가 전계에 기여하는 정도를 파악하였다. 컴프레서 소음에 가장 높은 영향을 미치는 1차모드를 고주파로 이동시키기 위하여, 1차 모드에 기여가 높은 분계의 질량과 강성을 변경하여 컴프레서 쉘의 동특성 개선 방향을 제시하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
• /
• pp.169-175
• /
• 1997

Recently it is increased by degrees to produce complex and large lattice structures such as bridge, tower, crane, and space structures. In general, in order to analyse these structures we have used finite element method(FEM). In this method, however, it is necessary to use a large amount of computer memory and to take long computation time. For overcoming this problem, the Authors have developed the transfer dynamic stiffness coefficient method(TDSCM) which consists on the concept of the substructure synthesis method and transfer influence coefficient method. In this paper, the new free vibration analysis method for large type lattice structure is formulated by the TDSCM. And the results obtained by TDSCM are compared with those obtained by FEM, transfer matrix method and experiment. And it is confirmed for TDSCM to be the numerical high accuracy and high speed structure analysis method.

• 오토저널
• /
• 제5권1호
• /
• pp.54-62
• /
• 1983

This paper presents structural analyses performed on the white body of vehicle using the most competitive analyzer, Finite Element Method, and attempts to obtain design criteria of body. By applying the substructure and restart technique to structural model, computation time is reduced. The synthetic processing from modelling to graphic visualization is accomplished by several subprograms, viz., various pre-post processors. On the basis of home-made vehicle modeling, typical cases of accident and service load is analyzed and discussed. The results obtained will guide the designer to design the structure optimally.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2000년도 추계학술대회 논문집
• /
• pp.328-335
• /
• 2000

The substructure of Light Rail Transit is mainly built on elevated structure that is composed of pier, girder and bridge deck. The bridge deck mostly has been made by field formed reinforced concrete so far. The objectives of the study are to find a method for design and construction of the new bridge deck. I-beam is fabricated to make grid and concrete is poured on it at factory. This type can be used for maintenance of duty line by advantages such as good quality control and short construction time.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1995년도 추계학술대회논문집; 한국종합전시장, 24 Nov. 1995
• /
• pp.116-122
• /
• 1995

본 논문에서는 컴프레서 쉘의 구조해석을 수행하기 위하여, 범용 구조 해석 패키지인 MSC/NASTRAN을 이용하여 컴프레서 쉘 전체의 동특성 해석을 수행하였으며, MSC/NASTRAN의 Superelement 모듈인 부분구조합성법을 이용하여 구조물 전체의 동특성해석을 수행하였다. 그리고, 각 분계의 변형 및 운동 에너지를 산출하여 전체 구조물의 고유모드에 대한 분계의 기여도를 평가하였으며, 각각의 에너지에 기여가 높은 분계의 형상을 변경하여 구조물 전체가 원하는 동특성을 얻도록 하였다.

• 한국생명과학회:학술대회논문집
• /
• 한국생명과학회 2008년도 제49회 학술심포지움 및 국제학술대회
• /
• pp.67.2-67.2
• /
• 2008

• Journal of Mechanical Science and Technology
• /
• 제16권10호
• /
• pp.1201-1210
• /
• 2002

A penalty frame method is proposed for the coupled analysis of finite elements with independently modeled substructures. Although previously reported hybrid interface method by Aminpour et al (IJNME, Vol 38, 1995) is accurate and reliable, it requires non-conventional special solution algorithm such as multifrontal solver. In present study, an alternative method has been developed using penalty frame constraints, which results in positive symmetric global stiffness matrices. Thus the conventional skyline solver or band solver can be utilized in the solution routine, which makes the present method applicable in the environment of conventional finite element commercial software. Numerical examples show applicability of the present method.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
• /
• pp.133-136
• /
• 2006

The top-down construction method is an excavation and substructure construction method by excavating earth and building slabs from the ground level to the bottom of a building. The top-down method can be categorized into several types by its process and other technical details. Some of commonly used top-down methods in Korea today are S.O.G., N.S.T.D., and S.P.S. Among these, one method is chosen depending on construction field conditions, cost, construction time and so on. This study explores several factors that may affect the selection of a top-down method. This paper reports preliminary survey results with 54 top-down construction experts and comparison results of 5 top-down construction sites.

• 대한기계학회논문집
• /
• 제18권6호
• /
• pp.1503-1509
• /
• 1994

An analysis method is suggested and experimentally studied in order to solve a vibration problem of a flexible structure while it is moving. In this method, substructure synthesis method, modal analysis method and Newmark's integral method were used. Total deformation of a structure was composed of quasistatic component and dynamic component. Rigid body modes were considered in calculation of dynamic component. Combining those two component, deformation behavior and a real structural model of a transfer feeder showed good agreements with computational results.