• 소성∙가공
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• 제20권2호
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• pp.104-109
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• 2011

The metal front case of a mobile phone is manufactured by press forming and welding of thin metal sheets. Twisting of the frame after the forming process is one of main obstacle for the assembly with reinforcement by welding. This study introduces a method preventing twisting of the metal front case frame in press forming. The spring-back after forming produces twisting of the frame, which leads to a low structural stiffness. To reduce twisting, connectors are required to reinforce the structural stiffness of the frame. In this study, the twisting profile is evaluated using a finite element(FE) analysis for various connector shapes. The actual connector shape is determined by minimization of the frame twisting within the tolerance of the FE-analysis. To verify the validity of the proposed blank shape, a forming experiment is performed and the twisting profile is measured using a 3D laser scanning method. The dimensional accuracy is found to be within the tolerance and in good agreement with the FE-analysis.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1997년도 가을 학술발표회 논문집
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• pp.177-184
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• 1997

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.253-257
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• 1996

A basic assumption in the current design and analysis of reinforced concrete(RC) box structures, which are constructed by the open cut and fill method, is that the displacements and forces are uniform in the longitudinal direction of the structure. The solution may be therefore obtatined from the analysis of a unit wide strip along longitudinal axis. This strip is said to be in a plane strain condition, meaning that the out of plane deformations are vanished. The current design of box structure is carried out by the result of planar frame model for the sake of simplicity. The purpose of this study is to show more rational design method of box culverts considering a rigid zone of corner joints. The current analysis of box structures will be compared with the plane strain analysis as well as 3-d shell model. Reinforcement quantity is also determined to resist the tensile force in corner joints of box structures using strut-tie model which has been developed through the elastic analysis.

• Steel and Composite Structures
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• 제9권4호
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• pp.381-395
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• 2009

This paper presents the details of an advanced Finite Element (FE) analysis of a plane steel portal frame with semi-rigid beam-to-column connections subjected cyclic loading. In spite of several component models on cyclic behaviour of connections presented in the literature, works on numerical investigations on cyclic behaviour of full scale frames are rather scarce. This paper presents the evolution of an FE model which deals comprehensively with the issues related to cyclic behaviour of full scale steel frames using ABAQUS software. In the material modeling, combined kinematic/isotropic hardening model and isotropic hardening model along with Von Mises criteria are used. Connection non-linearity is also considered in the analysis. The bolt slip which happens in friction grip connection is modeled. The bolt load variation during loading, which is a pivotal issue in reality, has been taken care in the present model. This aspect, according to the knowledge of the authors, has been first time reported in the literature. The numerically predicted results using the methodology evolved in the present study, for the cyclic behaviour of a cantilever beam and a rigid frame, are validated with experimental results available in the literature. The moment-rotation and deflection responses of the evolved model, match well with experimental results. This proves that the methodology for evolving the steel frame and connection model presented in this paper is closer to real frame behaviour as evident from the good comparison and hence paves the way for further parametric studies on cyclic behaviour of flexibly connected frames.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.344-351
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• 1999

Stress analysis of bogie frame by using the finite element method has been performed for the various loading conditions according to the UIC (International Union of Railways) Code 615-4. Multiaxial fatigue damage models such as signed von Mises method and typical critical plane theories were reviewed, and multiaxial fatigue analysis program (MUFAP) has been developed. Fatigue analysis of bogie frame under multiaxial loading was performed by using MUFAP and finite element analysis results. The procedure developed in this study is considered to be useful for the life prediction in preliminary design stage of railway components under multiaxial loading conditions. 3-dimensional surface modeling, mesh generation and finite element analysis were performed by Pro-Engineer, MSC/PATRAN and MSC/NASTRAN, respectively, which were installed in engineering workstation.

• Coupled systems mechanics
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• 제5권2호
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• pp.127-144
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• 2016

Two dimensional numerical investigations were carried out to study the influence of interface thickness and their pattern on the behavior of reinforced concrete frames subjected to in-plane lateral loads using commercial finite element tool SAP 2000. The linear elastic analysis was carried out on one and two bay structural systems as well as the influence of number of stories was studied by varying the number of stories as single, three and five. The cement mortar was used as interface material and their effect was studied by varying thicknesses as 6, 8, 10, 14 and 20 mm. The interface was recognized as one sided, two sided, three sided and four sided and their effect was studied by removing the interface material between the reinforced concrete frame and masonry infill. The effect of lateral loads on infill masonry wall was also studied by varying assumed loads as 10, 20, 30, 40, 50 and 60 kN. The behavior of infilled frames studied has revealed that there is a maximum influence of interface thickness and interface pattern corresponding to 10 mm thickness. In general, the lateral displacement of frame is increased linearly with increase in lateral loads.

• Earthquakes and Structures
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• 제5권1호
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• pp.111-127
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• 2013

This paper describes effects of infill walls on behavior of RC frame with low strength, including numerical modeling, modal testing and finite-element model updating. For this purpose full scaled, one bay and one story RC frame is produced and tested for plane and brick in-filled conditions. Ambient-vibration testis applied to identify dynamic characteristics under natural excitations. Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods are used to obtain experimental dynamic characteristics. A numerical modal analysis is performed on the developed two-dimensional finite element model of the frames using SAP2000 software to provide numerical frequencies and mode shapes. Dynamic characteristics obtained by numerical and experimental are compared with each other and finite element model of the frames are updated by changing some uncertain modeling parameters such as material properties and boundary conditions to reduce the differences between the results. At the end of the study, maximum differences in the natural frequencies are reduced on average from 34% to 9% and a good agreement is found between numerical and experimental dynamic characteristics after finite-element model updating. In addition, it is seen material properties are more effective parameters in the finite element model updating of plane frame. However, for brick in-filled frame changes in boundary conditions determine the model updating process.

• Steel and Composite Structures
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• 제52권1호
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• pp.77-87
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• 2024

Analytical methods for assessment of the out-of-plane buckling of unbraced top chords of truss bridges may look obsolete while comparing them to finite element analysis. However they are, usually, superior when rapid assessment is necessary. Analytical methods consider the top chord as a bar on elastic supports provided by bracing (Holt, Timoshenko). Correct assessment of the support elasticity (stiffness) is crucial. In the case of truss bridge spans of traditional structural layout (cross-beams at the truss chord nodes only), the elasticity may be set based on the analysis of the, so called, U-frame stiffness. Here the analyses consider the U-frame itself (a pair of verticals and a cross-beam) or the U-frame with adjacent diagonals or the pair of diagonals (in the absence of verticals) and the members of the bottom chord in the adjacent panels. For all the cases, the stability analysis of the chord as a bar in compression is necessary. Unfortunately, the method cannot be applied to contemporary truss bridges without verticals, that usually have independent cross-beam decks (the cross-beams attached to truss chords at their nodes and between them). This is the motivation for the analysis resulting in the method of setting the stiffness of the equivalent U-frame for the aforementioned truss bridges. Truss girders of both, gussetless and gusseted, joints are taken into account.

• 대한토목학회논문집
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• 제13권1호
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• pp.13-24
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• 1993

가상(假想)일의 원리(原理)를 이용하여 강절(剛節)-힌지단(端)을 갖는 평면(平面)뼈대요소(要素)와 비대칭(非對稱) 박벽단면(薄壁斷面)을 갖는 공간(空間)뼈대요소(要素)의 접선강도(接線剛度)매트릭스가 유도된다. 양단(兩端) 구속(拘束)된 비틂을 무시하는 경우, 구속(拘束)된 비틂을 고려하는 경우, 그리고 왼쪽단은 구속(拘束)된 비틂을 고려하고 오른쪽단은 구속(拘束)된 비틂을 무시하는 경우 각각에 대하여 박벽공간(薄壁空間)뼈대요소(要素)의 탄성(彈性) 및 기하적(幾何的)인 강도(剛度)매트릭스를 산정한다. 이때, 휨을 받는 평면(平面)보의 처짐함수를 적절히 선택하여 공간(空間)뼈대요소(要素)의 세방향처짐과 비틂회전각에 대한 형상함수(形狀函數)로 사용한다. 공간(空間)뼈대 구조물(構造物)과 원형(圓形)아아치의 횡좌굴(橫挫屈)문제를 해석(解析)하여 본(本) 연구(硏究)에 의한 해석결과(解析結果)들과 엄밀해(嚴密解) 또는 다른 문헌(文獻)의 결과(結果)들과 비교(比較) 분석(分析)하여 본(本) 연구(硏究)에서 제시한 이론(理論)의 정당성(正當性)을 입증(立證)한다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.306-313
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• 1998

Contrary to reinforced concrete frames, the beams or girders found in actual steel frames are neither hinged nor fixed at their ends. Instead, they are usually restrained by the columns to which they are attached. Here in this paper, common finite element program for plane frame stress analysis is improved by including the effect of partial fixities of the girder ends. To include the effect of partial fixities of the girder ends, Kim's modified slope-deflection equation is adopted. The stress analysis results obtained by this proposed method are then compared with Kim's example. Finally, method of choosing the most economic girder section for a multi-story frame is suggested through the examples.