현수교의 기하학적 비선형해석

방명석,Bang, Myung-Suk 한국전산구조공학회 1994 전산구조공학 Vol.7 No.3

The purpose of this study is to develop the analytical method and to analyze the geometrically nonlinear behavior of suspension bridges. Two step algorithm is developed to analyze the initial profile under the deal load and the nonlinearity under the live load. Since the geometrically nonlinear effect is great comparing with the linear analysis, it should be considered in the analysis and design. The comparison between analysis and measurement shows that the new algorithm is effective. 현수교의 기하학적 비선형거동을 해석할 수 있는 해석방법을 개발하고 해석을 실시하였다. 해석은 사하중하에서의 초기형상해석과 활하중하에서의 비선형해석의 2단계로 해석하는 알고리즘을 개발하였다. 선형해석 결과와 비선형해석결과를 비교할 때 기하학적인 비선형 효고가 매우 크므로 해석 및 설계시에 반드시 고려해야 함을 알 수 있다. 해석치와 측정치를 비교분석한 결과 새로운 알고리즘이 매우 유용함을 보여주고 있다.

트러스구조물의 확률론적 유한요소 해석

방명석,Bang, Myung Suk 대한토목학회 1993 대한토목학회논문집 Vol.13 No.1

탄성계수의 확률분포를 고려한 트러스 구조물의 유한요소 해석을 수행하였다. 탄생계수의 분포함수를 이용한 형상함수를 유도하여 강성행열을 구성하고 Monte Carlo Simulation 기법을 이용하여 수치해석을 수행하였다. 공간 트러스 구조물 해석을 통해서 해석과정을 검증하고 사장교에서 케이블 장력의 변동폭을 예측하였다. Finite element analyses are conducted with stochastic elastic moduli when truss structures are subjected to static loads of a deterministic nature. Stochastic stiffness matrix is derived from stochastic shape functions and numerical analyses are performed within the framework of the Monte Carlo method. Analysis methods are verified for the space truss and applied to cable stayed bridge for determining the cable force.

콘크리트의 손상모델에 관한 실험적 연구

방명석,Bang, Myung Suk 대한토목학회 1991 대한토목학회논문집 Vol.11 No.1

콘크리트는 고응력 범위에서 적은 반복횟수에 의해서도 파괴에 도달할 수 있고 소성 변형에 의한 콘크리트 손상이 심각하다. 본 연구에서는 반복하중하에서의 콘크리트의 손상과정에 관하여 실험적으로 연구하였고 에너지개념에 의한 소상모델을 개발하였다. 실험은 일축압축상태의 무근콘크리트에 대해서 변위제어상태하에서 수행하였다. 콘크리트의 파괴시점은 잔여강도가 존재하지 않은 상태까지로 가정하였고, 손상도는 실험적으로 파괴시까지 구해진 에너지 발산량과 주어진 횟수의 반복하중에 의한 에너지 발산량의 비로 정의하였다. 고응력 범위에서 손상도는 변형량의 비선형함수로 누적되며, 손상비율은 초기에 높고 파괴상태에 가까울수록 점차적으로 감소하였다. The concept of damage is all-pervasive in structural engineering. It can be considered a state variable and defined to vary from 0(no damage) to 1(failure). Thus, the factor of safety against failure, the most important aspect of a structure, cannot be assessed without evaluating the damageability of a structure under load. It is the objective of the research reported herein to study the behavior of concrete under repeated load applications. Concrete is known to deteriorate under such loading, i.e., it suffers damage of increasing degree. Its response to future loading is a function of the amount of damage sustained during previous load exposures. The same can be said about reinforced concrete members and entire structures, but here we wish to consider only plain concrete and express some of its material properties as functions of the degree of sustained damage. The work described herein is based on the stipulation that the energy dissipation capacity of plain concrete is a material property and the damage accumulates in direct proportion to the degree to which the energy dissipation capacity is being exhausted, in some analogy to both high- and low-cycle failure behavior of materials.

감차적분(減次積分) 비적합변위형(非適合變位形)을 혼합사용한 평판요소(平板要素)의 개발(開發)

방명석,최창근,Bang, Myung Suk,Choi, Chang Kuen 대한토목학회 1985 대한토목학회논문집 Vol.5 No.2

감차적분(減次積分)과 비적합변위형(非適合變位形)을 혼합사용함으로써 고도로 효율적인 새로운 평판요소가 개발되었다. 이 요소의 변위영역은 Ahmad-Irons 요소의 횡방향성분에만 비적합변위형(非適合變位形)을 추가하였고, 요소강성행열은 수정된 차수(次數)의 수치적분에 의하여 계산된다. 다른 요소들과 비교하여 NC 8-4.1과 NC 8-5.1 요소들의 월등함이 발견되었다. 이 요소들에 의한 해는 mesh가 세분됨에 따라 정확한 해에 급속히 수렴함을 알 수 있다. 또한 이 요소들은 두꺼운 펑판문제에서 부터 매우 얇은 평판문제까지 넓은 범위에 적용할 수 있음을 보여 준다. By the combined use of reduced integration and addition of nonconforming displacement modes, a highly effective new plate element has been established. The displacement field of this element was formed by adding nonconforming modes only to transverse displacement component of Ahmad-Irons' element and the element matrices are computed by the numerical integrations with modified orders. Comparing with other elements, the superiority of the both NC 8-4.1 and NC 8-5.1 elements over the elements previously studied has been observed. The solutions with these elements converge to the true solutions very rapidly as the mesh is refined. These elements are also shown to be applicable to the wide range of thick and very thin plate problems.

시공 방법을 고려한 현수교의 시공단계별 해석

한성호(Han Sung Ho),이강혁(Lee Kang Hyuk),신재철(Shin Jae Chul),방명석(Bang Myung Suk) 대한토목학회 2005 대한토목학회 학술대회 Vol.2005 No.10

도시철도 인접굴착진동의 동적영향 연구

최준혁(Jun Hyuck Choi),한우진(Woo-Jin Han),방명석(Myung-Suk Bang) 한국철도학회 2023 한국철도학회 학술발표대회논문집 Vol.2023 No.5

현수교의 비선형해석에 관한 연구

박종섭(Jong Sup Park),김철영(Chul Yung Kim),방명석(Myung Suk Bang) 한국강구조학회 1995 韓國鋼構造學會誌 Vol.7 No.3

An analysis method to investigate the characteristics of three dimensional behaviour of a suspension bridge after construction is presented in this study. A nonlinear static analysis program for the suspension bridge is also developed. Three dimensional frame element with 7 degrees of freedom at each node including warping and flexural-torsional coupling effect is used to model towers and stiffening girders. Generally, cable is an element which has no resistance to bending and compression but only resistance to tension. Therefore, main cables exhibit complex nonlinear behaviour because of the large deformation when they are loaded. In order to consider these effects, elastic catenary cable element developed from the exact solution of a nonlinear differential equation of an elastic catenary cable subjected to self-weight is used to model main cable and hangers. Through Nam-Hae bridge analysis, it has been found that procedures suggested in this study can be applied effectively to three dimensional nonlinear static analysis of a suspension bridge.

근거리지진의 특성과 동적응답스펙트럼에 관한 연구

方明錫 충주대 2004 産業科學論文集 Vol.12 No.-

The characteristics of Near Fault Ground Motions is analyzed and ductility response spectrums from them are developed in this study. The domestic design code was developed based on Far Fault Ground Motions, so the effects of Near Fault Ground Motions, which is very serious especially in large structures with a long period, are not considered in our design code. This study shows that developed response spectrums should be considered in the long period range of long span structures.

현수교의 기하학적 비선형을 고려한 동적 및 시공단계별 해석

방명석 한국산업안전학회 1999 한국안전학회지 Vol.14 No.4

Dynamic structural behavior in long span bridges, especially cable structures, is very sophisticated due to their flexibility and structural members are sequentially erected in each construction step. In this study, the consistent mass matrix for dynamic analysis is formulated and computational program considering construction sequences is developed where structural members can be builded or removed by command language and automatically reanalyzed in the moment when structural system is changed. The dynamic analysis, i.e. eigenvalue and time series analysis and the geometrically nonlinear analysis considering construction sequence are conducted to the Namhae Bridge. The analytical results are satisfactory compared with measuring values and the developed computational program can successfully be applied to design and safety check.

彈性懸垂要素의 質量行列構成에 의한 長大橋梁의 動力學的 解析

方明錫 충주대 산업과학기술연구소 1999 産業科學論文集 Vol.7 No.1

The dynamic structural behavior in long span bridges, especially cable structures, is very sophisticated due to their flexibility. In this study, the consistent mass matrix for dynamic analysis is formulated and the computational program is developed. The geometrically nonlinear analysis and the dynamic analysis, i.e. eigenvalue and time series analysis, are conducted to the Namhae bridge. The analytical results are satisfactory compared with measured values and developed computational program can successfully be applied to design work and safety check.