공용 중 현수교의 계측기반 해석모델 개발

김호경(Kim Ho-Kyung),이호(Lee Ho),장정환(Jang Jeong-Hwan),노상곤(Ro Sang-Kon) 대한토목학회 2007 대한토목학회논문집 A Vol.27 No.6A

현수교의 주케이블 장력은 전체구조계의 강성을 좌우하는 요소로서 구조형상을 계측함으로써 추정이 가능하다. 기존 발표된 형상해석법이나 형상해석 결과는 대부분 설계 시 이상화된 구조계에 대한 것이기 때문에 공용 중인 교량의 유지관리를 위한 해석모델을 작성 또는 보완하고자 할 때에는 계측자료를 활용하기 위한 별도의 배려가 필요하다. 이 연구에서는 공용중인 주경간 500 m의 3경간 현수교에 대하여 형상측량을 수행하고 중량변화 이력과 계측 행어 장력 등을 활용하여 현재 구조상태를 반영한 현수교 해석모텔을 제안하고자 하였다. 고정하중에 대한 형상해석 결과를 토대로 선형화 유한변위해석 모델을 제시하고 형상 및 온도 계측결과 등을 점진적으로 반영함으로써 일반적 형상해석법으로부터 계측기반 형상해석법으로의 확장을 시도하고자 하였다. 검토결과 대상교량의 공용 중 형상은 목표 형상과 비교적 잘 일치하는 것으로 파악되었다. 하나의 해석모델 보완법을 제시함으로써 향후 다양한 유지관리 자료를 토대로 현수교의 해석모델을 작성할 수 있는 이론적 기틀을 제공하고자 하였다. The tension of the main cables in a suspension bridge is influencing critically the stiffness of the whole structural system and can be indirectly measured through the survey of its configuration. Since previously published shape-finding analysis methods or results are mostly based on the idealized structural system adopted during design, need is to pay particular attention on the exploitation of field-measured data when establishing or updating the analysis model for maintenance purpose of the bridge in service. This study intends to propose an analytic model for an actual 3-span suspension bridge with main span of 500m using the measurement resulting from its configuration survey. Based on the shape-finding analysis results relative to the dead loads, a linearized finite displacement FE model is proposed and, an attempt to extend the measurement-based shape-finding analysis method from conventional methods by reflecting progressively the measured configuration and temperature is presented. Analysis results reveal that the current configuration of the bridge in service corresponds fairly with the target configuration. This study proposes a model updating method which could provide theoretical basis for the establishment of analysis model for suspension bridges based on various maintenance data.

가상점성감쇠요소를 이용한 막구조물의 형상해석

김정화(Kim Jung-Hwa),한상을(Han Sang-Eul),이경수(Lee Kyong-Soo) 대한건축학회 2007 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.27 No.1

In shape-finding process of membrane structure by dynamic relaxation method, three-node triangular membrane elements, the finite elements, are generally used. But serious changes of curvature in many membrane structures can make the mesh distortion. As a result, the final form of the membrane is not appropriate for the patterning and the stress analysis. To solve these problems, the artificial viscous damping element is introduced to control the mesh distortion. It is placed at three sides of a triangular membrane element and the nodal force, residual force, can be controled by the damping force. Also, it does not prevent the convergence of residual force. The damping element is applied to various models to evaluate the improvement of mesh distortion and it is verified that the introduction of artificial viscous damping element can control the mesh distortion, efficiently.

가상점성감쇠요소 도입에 의한 막구조의 형상탐색에 관한 연구

한상을(Han Sang-Eul),이경수(Lee Kyong-Soo),김정화(Kim Jung-Hwa) 대한건축학회 2007 大韓建築學會論文集 : 構造系 Vol.23 No.11

In shape-finding process of membrane structure by dynamic relaxation method, three-node triangular membrane elements, the finite elements, are generally used. But serious changes of curvature in many membrane structures can make the mesh distortion. As a result, the final form of the membrane is not appropriate for the patterning and the stress analysis. To solve these problems, the viscous damping element is introduced to control the mesh distortion. It is placed at three sides of a triangular membrane element and the nodal force, residual force, can be controled by the damping force. Also, it does not prevent the convergence of residual force. The damping element is applied to various models to evaluate the improvement of mesh distortion and it is verified that the introduction of viscous damping element can control the mesh distortion, efficiently.

Adaptive Sampling Method of Suspension-Bridge Finite Element Models Based on Coupled Modeling Approach

Lingfeng Luo,Deshan Shan,Miao He 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.10

This paper presents an accurate sampling method for suspension-bridge finite element (FE) model updating. The proposed method utilizes a coupled suspension-bridge modeling approach, which integrates a numerical shape-finding method with conventional FE analysis to efficiently achieve parametric modeling during the sampling process. This study also employs the Nelder-Mead algorithm (NMA) to ensure the efficiency and robustness of the numerical shape-finding calculation. First, the accuracy of the NMA-based coupled modeling approach is examined by numerical investigation of the baseline model of an actual suspension bridge. Then, the computational results of two groups of samples with different sample sizes are compared to test the efficiency of the proposed method. Finally, by relying on the structural health monitoring (SHM) system of this bridge, the measured natural frequencies over half a year are identified, and almost all of them are within the calculated sample space.Therefore, the feasibility of the proposed suspension-bridge FE model sampling method is validated by the uncertainties of the measured responses over half a year.

Geodesic shape finding of membrane structure with geodesic string by the dynamic relaxation method

K.S. Lee,한상을 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.1

The explicit nonlinear dynamic relaxation method (DRM) is applied to the nonlinear geodesic shape finding analysis by introducing fictional tensioned ‘strings’ along the desired seams with a three or four-node membrane element. A number of results from the numerical example for the nonlinear geodesic shape finding and patterning analysis are obtained by the proposed method to demonstrate the accuracy and efficiency of the developed method. Therefore, the proposed geodesic shape finding algorithm may improve the applicability of a four-node membrane element to membrane structural engineering and design analysis simultaneously for the shape finding, stress, and patterning analysis.

Geodesic shape finding of membrane structure with geodesic string by the dynamic relaxation method

Lee, K.S.,Han, S.E. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.1

The explicit nonlinear dynamic relaxation method (DRM) is applied to the nonlinear geodesic shape finding analysis by introducing fictional tensioned 'strings' along the desired seams with a three or four-node membrane element. A number of results from the numerical example for the nonlinear geodesic shape finding and patterning analysis are obtained by the proposed method to demonstrate the accuracy and efficiency of the developed method. Therefore, the proposed geodesic shape finding algorithm may improve the applicability of a four-node membrane element to membrane structural engineering and design analysis simultaneously for the shape finding, stress, and patterning analysis.

아치구조의 최적형상 탐색

이상진(Lee, Sang-Jin) 대한건축학회 2022 대한건축학회논문집 Vol.38 No.5

This study proposes a shape finding method for arch structure. It aims to provide a general procedure for finding the optimal shape of arch structures using the optimization technique. All the process is utilized by using the visual programming technique. The NURBS (Non-Uniform Rational B-spline) definition is introduced to represent the geometry of the arch structure. The strain energy of the arch structure is evaluated by using the plug-in Karamba3D in Grasshopper environment. The shape optimization with the strain energy to be minimized and height constraint is then performed by using the plug-in NM-opti. Numerical examples are carried out to verify the capability of the present shape finding method and to find the optimum shape of the arch in various situations. From numerical examples, the present shape finding method can effectively produce a new optimum shape of the arch regardless of natural and essential boundary conditions.

형상조절기법을 포함하는 내력밀도법에 관한 연구

배정은(Bae Jung-Eun),이상진(Lee Sang-Jin) 대한건축학회 2011 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.31 No.2(구조계)

This paper describes a study of form finding process of arch-like truss using force density method (FDM) with a shape control technique. When we try to find a form of structure based on FDM, we can get all possible shapes with only knowing element connectivity and giving various force density values. However if we want to give certain restriction to a shape of structure such as height or element length, then we would have to repeat iterations by trial and error when we use original FDM to satisfy those restrictions. To resolve the problem, this study is carried out to find and suggest a technique that includes a shape constraint during the form finding process based on FDM.

비선형 형상 탐색 기법에 따른 막구조물의 오차와 수렴성 평가에 관한 연구

손수덕,김승덕,정을석,전진형 한국공간구조학회 2007 한국공간구조학회지 Vol.7 No.3

연성구조시스템 중 하나인 막 구조물은 대공간 구조물에 많이 사용되어진다. 막 구조물은 축강성이 강하고 휨강성이 매우 작은 재료로서 구조물의 설계는 강성구조물과는 달리 형상해석, 응력-변형해석 그리고 재단도 등의 일련의 과정을 필요로 한다. 막 구조물의 형상해석은 일반적으로 초기 불안정 상태의 막 면에 초기강성을 부여함으로서 평형상태에 이르게 되는 역학적 메커니즘을 가지고 있으며, 이와 같은 곡면을 해석적으로 구하는 데는 해석상의 수렴 및 발산 그리고 오차 발생에 따른 문제를 해결해야만 한다. 본 논문에서는 막 구조물의 초기곡면을 형성하기 위한 형상탐색기법에 대한 수렴 및 오차에 관하여 연구하고, 적용된 예제의 해석 결과를 바탕으로 해가 수렴해 가는 과정 및 제어변수에 따른 수렴속도 및 효율성을 살펴본다. The membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and happen large deformation phenomenon. Therefore, in this paper, we investigate the convergence of solution and the speed according to the control variables and the method of shape analysis.

Improved Methods for Determining the 3 Dimensional Initial Shapes of Cable-Supported Bridges

김문영,김동영,정명락,Mario M. Attard 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.1

The TCUD method (Kim and Lee, 2001) can minimize undesirable lateral displacements in cable bridge structures byincluding the unstrained lengths of the cable members as unknowns and introducing additional constraint conditions. The axialdeformations in the girder and the main tower deviating from the target configuration are, however, unavoidable when selfanchoredcable bridges are considered. On the other hand, the IFM (initial force method) can be used to adjust the axialdeformations to conform to the initial shape but it is critical that the unstrained lengths of the cables are accurately evaluated. In this study, improved schemes for the TCUD method and the IFM for finding the initial shape of 3 dimensional cablesupportedbridges under dead load, are presented. For this purpose, the TCUD method and the initial force method are firstlyreviewed. Two improved algorithms, which can overcome shortcomings of the previous initial-shaping analysis methods, aredeveloped based on an elastic catenary cable element and a nonlinear space frame element. Finally, the accuracy andeffectiveness of the proposed analysis algorithms are demonstrated through the numerical application to 3 dimensional initialshape problems for self-anchored suspension and cable-stayed bridges.