Proceedings of the Computational Structural Engineering Institute Conference (한국전산구조공학회:학술대회논문집)
Computational Structural Engineering Institute of Korea (COSEIK)
- Semi Annual
Domain
- Construction/Transportation > Design/Analysis for Facilities
2005.04a
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The structural analysis considering the soil-structure interaction is very important in the design process of underground structures located on the site with various soil conditions. In practice, simplified modelling techniques to obtain the approximate solution are used in accordance with the specifications. However, their details are insufficient for practical engineers to obtain the stable solutions and the analysis results of each engineer occasionally my be different in spite of the same problem. In this study, the sensitivity of structural behaviour on the underground structures is analyzed according to the structural modelling techniques of existing specifications. It is performed to obtain the fundamental informations to establish the guide to obtain the stable solutions in practical analysis of the underground structures such as subway structures.
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The single layer latticed dome is very sensitive on the slenderness ratio and half open angle of the elements, load condition and the connection type because it is organized by a lot of thin elements, so we have to use the geometrically nonlinear buckling load when the buckling behavior of the structures is analyzed But, it is very difficult to design the single layer latticed domes considered all conditions. Therefore the purpose of this paper is to propose the appropriate design method of the single layer latticed dome considered the geometrically nonlinear buckling load in base on the linear buckling load by the eigen-value analysis.
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Solar radiation causes non-uniform temperature distribution in the structure, depending on the shape of the structure and its shadows. Especially in cases of curved steel box girder bridges, non-uniform temperature distribution due to solar radiation can reduce bridge life and serviceability when combined with another load combination. In this study, the method for predicting the temperature distribution of curved bridges developed by Kim et al., was used to predict the non-uniform temperature distribution which served as a basis for structural analysis of 3-D bridge behavior. In order to seek the most unfavorable conditions of solar radiation, observation data from the Korea Meteorological Administration for solar radiation were analyzed. The region of the most high solar radiation condition was selected and its one year variation of the solar radiation data was considered. From this analysis, the most unfavorable solar radiation condition with lower solar altitude and intense solar radiation was selected. Based on the selected solar radiation condition, structural behavior of curved bridges with diverse bridge direction, span length, radius and support conditions are analyzed.
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It is now well recognized that the ultimate limit state approach is a much better basis for design and strength assessment of ships and offshore structures since it is difficult to determine the realistic margin of safety using the traditional allowable working stress approach on the basis of linear elastic method solutions together with buckling strengthchecks adjusted by a simple plasticity correction. This paper outlines ALPS theory for ultimate limit state assessment of ship structures. ALPS is a computer software which stands for nonlinear Analysis of Large Plated Structures. Application examples of ALPS program to ultimate limit state assessment of plates, stiffened panels and ship hull girders are presented. A benchmark study is made by a comparison with the ALPS solutions with other methods including class rule formulae, nonlinear finite element methods and experimental results. Future trends on ultimate limit state assessment of ship structures are addresse[1]
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Stiffness reduction factor of slab in flat-plate structure is proposed in comparison with UCB test result. Then analysis of structural system of flat-plate apartment buildings is carried out by using effective beam width method and finite element method. Effective beam width method overestimates the lateral stiffness of the system where columns are arranged atypically and overestimates the stiffness of slab-wall joint.
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A web-based platform for structural analysis has been developed. The proposed web-based platform is a 2-tier system composed o( client and server sides to reduce the overburden on the server side. Smart Client is applied for the client side to improve the handling speed and UI. For the server side, MSSQL is applied to deal with database and used as a storage for the web. XML WebService is adpoted for the networking between the client and the server. To examine the efficiency of the developed web-based platform a sample study is carried out with a nonlinear earthquake analysis on a SDOF system.
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In this paper, a CAB/CAE integrated optimal design system is developed, in which design and analysis process is automated using CAD/CAE softwares, for a complicated model for which parametric modeling provided by CAD software is not possible. CAD modeling process is automated by using UG/OPEN API function and UG/Knowledge Fusion provided by Unigraphics. The generated model is transferred to the analysis code ANSYS in parasolid format. Visual DOC software is used for optimization. The system is developed for PLS(Plasma Lighting System), which is a next generation illumination system that is used to illuminate stadium or outdoor advertizing panel. The PLS system consists of more then 20 components, which requires a lot of human efforts in modeling and analysis. The analysis for PLS includes static load, wind load and impact load analysis. As a result of analysis, it is found that the most critical component is a tilt assembly, which links lower & upper body assembly. For more reliable analysis, experiment is conducted using MTS and compared with the Finite element analysis result. The objective in the optimization is to minimize the material volume under allowable stresses. The design variables are three parameters in the tilt assembly that are chosen to be the most sensitive in stress values of twelve parameters. Gradient based method and RSM(Response Surface Method) are used for the algorithm and the results are compared. As a result of optimization, the maximum stress is reduced by 57%.
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For using narrow site effectively, recently constructions of high-rise buildings have been increased. High-rise buildings are mainly governed by wind loads. Since wind flow Is vaned irregularly, the experimental method such as wind tunnel test is used to evaluate real wind loads. In this study, it is intended to estimate design wind pressure and amounts of material of cladding by AIK recommendations and wind tunnel test. Also, this study includes the investigation of reliability, suitability and economical efficiency in design of cladding of buildings by AIK recommendations and wind tunnel test by comparing and examining various results. Finally, it is concluded that not only AIK recommendations but also wind tunnel test should be considered to get the reasonable wind pressure acting on the cladding of high-rise buildings.
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In performance-based design methods, it is clear that the evaluation of the nonlinear response is required. The methods available to the design engineer today are nonlinear tim history analyses, or monotonic static nonlinear analyses, or equivalent static analyses with simulated inelastic influences. The nonlinear time analysis is the most accurate method in computing the nonlinear response of structures, but it is time-consuming and necessitate more efforts. Some codes proposed the capacity spectrum method based on the nonlinear static analysis to determine earthquake-induced demand given the structure pushover curve. This procedure is conceptually simple but iterative and time consuming with some errors. The nonlinear direct spectrum method is proposed and studied to evaluate nonlinear response of structures, without iterative computations, given by the structural linear vibration period and yield strength from the pushover analysis. The purpose of this paper is to compare the accuracy and the reliability of approximate nonlinear methods with respect to RC dual system and various earthquakes.
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This paper deals with the static optimal shapes of simple beams which are subjected to a vertical point load. The area and second moment of inertia of the regular polygon cross-section of the tapered beams are determined, which have always same volume and same length for the parabolic taper. The differential equation governing the elastic curve is derived using the small deflection theory and solved numerically. By using the numerical results of deflections, rotations and bending stresses of such beams, the optimal shapes, namely, optimal section ratios, of the beams subjected to a single point load according to variation of load position parameters are determined and presented in the figures. Examples of the static optimal shapes for beams with a single load and multiple loads are reported. The design process of this study can be used directly for the minimum weight design of simple beams.
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Numerical procedure of design optimality evaluation is studied for caisson structural systems. Two kinds of evaluation methods can be considered; mathematical optimality criteria method (MOCM) and numerical optimization method (NOM). The choice of the method depends on the available information of the system MOCM can be used only when the information of all function values, gradients and Lagrange multipliers is available, which may not be realistic in practice. Therefore, in this study, NOMs are applied for the structural optimality evaluation, where only design variables are necessary. To this end, Metropolis genetic algorithm (MGA) is advantageously used and applied for a standard optimization model of caisson composite breakwater. In the numerical example, cost and constraint functions are assumed to be changed from the orignal design situation and their effects are evaluated for optimality. From the theoretical consideration and numerical experience, it is found that the proposed optimality evaluation procedure with MGA-based NOM is efficient and practically applicable.
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The seismic behavior of framed structure with Chevron-type bucking restrained braces were investigated and their behavior factors were evaluated following the procedure proposed in ATC-19 & ATC-34. Two types of structures, building frame systems and dual systems, with 4, 8, 12, and 16 stories were designed per the IBC 2000, the AISC LRFD and the AISC/SEAOC Recommended Provisions for BRBF. Nonlinear static pushover analyses were carried out to observe the plastic hinge formation and to identify the loads and the displacements at the yield and the ultimate states. Time history analyses were also carried out to compute the permanent displacement md the dissipated hysteretic energy. According to the analysis results, the response modification factors of model structures fumed out to be larger than what is proposed in the provision in low story structures, and a little smaller in medium-story structures. The dual systems, even though designed with smaller seismic load, showed superior static and dynamic performances.
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Recently, Various structural systems for skyscrapers are studied as structures are more higher. The mega frame system of all, which is the structural system developed recently, are considered as a suitable structural system for skyscrapers. This structural system has sufficient stiffness for the lateral forces with mega-columns which consist of many columns and mega-girders which consist of girders with large stiffness or trusses. But there is no efficient analysis method and a design method for it. Therefore, an efficient analytical model, which has only DOFs selected by the user using the matrix condensation technique, is proposed in this study to obtain accurate results in significantly reduced computational time.
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To substitute conventional reinforced-concrete bridge deck glass composite precast bridge deck - Delta
$Deck^{TM}$ , which possesses advantages of light weight, high strength, corrosion resistance and durability, is developed for the DB24 truck load. Pultruded composite bridge deck is designed and fabricated. In this paper some field applications and field load test of developed composite deck bridge are presented. -
This study presents an effective stiffness-based optimal technique to control quantitatively lateral drift for shear wall structures subject to lateral loads. To this end the displacement sensitivity depending on behavior characteristics of shear wall structures is established. Also, the approximation concept that can preserve the generality of the mathematical programming and can efficiently solve large scale problems is introduced. Resizing sections in the stiffness-based optimal design are assumed to be uniformly varying in size and the technique of member grouping is considered for the improvement of construction efficiency Two types of 11-story shear wall structures are presented to illustrate the features of the quantitative lateral drift control technique proposed in this study.
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The focused topic according to be slender and longer of cable stayed bridge's main span is as follows (1) Aerodynamic stability (2) Lateral movement of stiffening girder caused by wind force during and after construction (3) Global bucking of stiffening girder caused by axial force Among this, the number 3 has not received much attention in the past due to high buckling safety factor of stiffening girder. However, according to be slender of stiffening girder, the topic of buckling stability of girder is not any more unconcerned subject. The purpose of this paper is to examine the effect of stay cable's nonlinear behavior on the buckling stability of cable-stayed bridge.
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In this study, to evaluate the collision behaviors of the navigating vessel and the dolphin protective system protecting the substructures of bridges, the numerical simulation was performed. The analysis model of vessel bow that the plastic deformations are concentrated was composed by shell elements, and the main body of vessel was modeled by beam elements to represent the mass distribution and the change of potential energy. The material model reflecting the confining condition was used for the modeling of the filling soil of dolphin system. The surrounding soil of the dolphin system was modeled as nonlinear springs. As results, it is verified that the dolphin system can adequately dissipate the kinematic energy of the collision vessel. The surrounding soil of the dolphin system is able to resist the collision force of the vessel. And the major energy dissipation mechanism of collision energy is the plastic deformation of the vessel bow and the dolphin system.
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For the safety analysis of large structures such as nuclear containment buildings, we conventionally prefer to use analytical approach using finite element method rather than empirical test. Therefor, this paper is mainly focused to develop low-order solid finite element model with the elasto-plastic material model for the safety analysis of nuclear containment building. Drucker-Prager failure criteria in uncracked concrete and maximum tensile stress criteria in cracked concrete are used to model the constitutive behavior of concrete. The concrete material model takes into account the aspects of tensile strain, compression strength reduction of concrete and shear transfer to improve the accuracy of the finite element analysis. Finally, numerical simulation to compare the performance of the developed model with experimental results is employed. The numerical results in this study agree very well with the experimental data.
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The vibration on building structures due to exciting vibration forces has been studied only for the vibration level on existing buildings. Recently, several researches have been performed on the prediction of vertical vibration on structures by using an analytical method. However, these studies have been focused on mainly the vibration analysis through analytical modeling of structures. This study aims to investigate the characteristics of vertical vibration transfer in terms of the directions of transfer(upward transfer and downward transfer) on the shear wall building structures due to 2 type vibration forces. In order to examine the characteristics of vertical vibration transfer, the mode analysis and the impact experiment were conducted several times on one building structure. The results of this study suggest that the characteristics of vertical vibration transfer are different in terms of the directions of transfer.
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Through time-dependent analyses of RC bridges constructed by a movable scaffolding system (MSS) considering the construction sequence and creep deformation of concrete, structural responses related to the member forces are reviewed. On the basis of the compatibility condition and equilibrium equation at every construction stage, basic equations that can describe the moment variation with time in movable scaffolding construction are derived. By using the introduced relations, the design moment and its variation over time can easily be obtained with only the elastic analysis results and without additional time-dependent analyses considering the construction sequences. In addition, the design moments determined by the introduced equations are compared with the results from a rigorous numerical analysis with the objective of establishing the relative efficiencies of the introduced equations.
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The present study is concerned with the application of dynamic relaxation method in the investigation of the large deflection behavior of spatial structures. This numerical algorithm do not require the computation or formulation of any tangent stiffness matrix. The convergence to the solution is achieved by using only vectorial quantities and no stiffness matrix is required in its overall assembled form. In an effort to evaluate the merits of the methods, extensive numerical studies were carried out on a number of selected structural systems. The advantages of using dynamic relaxation methods, in tracing the post-buckling behavior of spatial structures, are demonstrated.
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Nuclear containment structure is the last barrier for being secure from any nuclear power plant accident. Even though the safety requirements of nuclear power plant have been focused on removing accidental situations, nuclear containment structure must reserve the sufficient resisting capacity to any accident because it works as the last barrier. The acceptable nuclear containment structure makes possible to limit the effect of internal accidents and to avoid radioactive release. In this study, to conduct the numerical analysis for the structural safety of a containment structure, loss of coolant accident (LOCA) is considered as the basic accidental load, and Wolsong containment structure is considered as a target structure. The CANDU containment structure, such as Wolsong containment structure, is a prestressed concrete shell structure which has dome and is reinforced with bonded tendons. The evaluation of ultimate pressure capacity was conducted by nonlinear analysis of a prestressed concrete containment structure.
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To monitor the safety and serviceability of a structures, structural responses including displacements due to various design and unexpected loadings must be measured. The maximum displacement and its distributions of a structure can be used as a direct assessment index on its stiffness. For this reason, there have been diversely studied on measuring of the maximum displacement of a structure. However, there is no practical method for measuring displacement of a structure. Therefore, in this paper, new displacement measuring method is developed and accuracy of LiDAR is examined in detail for development of a new method for measuring displacement of a structure.
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Neuro-Fuzzy modeling approach is proposed to predict the dynamic behavior of a single-degree-of-freedom structure that is equipped with hybrid base isolation system. Hybrid base isolation system consists of friction pendulum systems (FPS) and a magnetorheological (MR) damper. Fuzzy model of the M damper is trained by ANFIS using various displacement, velocity, and voltage combinations that are obtained from a series of performance tests. Modelling of the FPS is carried out with a nonlinear analytical equation that is derived in this study and neuro-fuzzy training. Fuzzy logic controller is employed to control the command voltage that is sent to MR damper. The dynamic responses or experimental structure subjected to various earthquake excitations are compared with numerically simulated results using neuro-fuzzy modeling method. Numerical simulation using neuro-fuzzy models of the MR damper and FPS predict response of the hybrid base isolation system very well.
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The controller that can control the smart base isolation system consisting of M damper and friction pendulum systems(FPS) is developed in this study. A fuzzy logic controller (FLC) is used to modulate the M damper force because the FLC has an inherent robustness and ability to handle non-linearities and uncertainties. A genetic algorithm (GA) is used for optimization of the FLC. When earthquake excitations are applied to the structures equipped with smart base isolation system, the relative displacement at the isolation level as well as the acceleration of the structure should be regulated under appropriate level. Thus, NSGA-II(Non-dominated Sorting Genetic Algorithm) is employed in this study as a multi-objective genetic algorithm to meet more than two control objectives, simultaneously. NSGA-II is used to determine appropriate fuzzy control rules as well to adjust parameters of the membership functions. Effectiveness of the proposed method for optimal design of the FLC is judged based on computed responses to several historical earthquakes. It has been shown that the proposed method can efficiently find Pareto optimal sets that can reduce both structural acceleration and base drift from numerical studies.
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A higher order zig-zag shell theory is developed to refine the predictions of the mechanical and thermal behaviors partially coupled. The in-plane displacement fields are constructed by superimposing linear zig-zag field to the smooth globally cubic varying field through the thickness. Smooth parabolic distribution through the thickness is assumed in the out-of-plane displacement in order to consider transverse normal deformation and stress. The layer-dependent degrees of freedom of displacement fields are expressed in terms of reference primary degrees of freedom by applying interface continuity conditions as well as bounding surface conditions of transverse shear stresses. Thus the proposed theory has only seven primary unknowns and they do not depend upon the number of layers. In the description of geometry and deformation of shell surface, all rigorous exact expressions are used. Through the numerical examples of partially coupled analysis, the accuracy and efficiency of the present theory are demonstrated. The present theory is suitable in the predictions of deformation and stresses of thick composite shell under mechanical and thermal loads combined.
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In this paper, to prediction of large deformation behavior of steel structures under loading, 3-Dimensional elastic-plastic FE analysis method is developed by using finite deformation theory and proposed cyclic plasticity model. The accuracy of developed analytical method was verified by comparison of experiment result and analysis results using infinitesimal deformation theory. The good agreement between analysis result by developed analytical method and experiment result is shown. Proposed 3-dimensional FE analysis using finite deformation theory and cyclic plasticity hysteresis model can be predict the large deformation of steel members under cyclic loading.
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The objective of this study is to evaluate the simulated effects of axial and off-axial vertical loads at the implant/bone interface and the stress distribution according to the bone density of a single-unit dental implant in the cylinder and square thread implants by 3D FEA The implants were placed in the mandibular model with 25mm in height, 15mm in width and 20mm in length; then the mandibular bone density was classified into the bone type : I, II III and IV. In addition, the force were applied into 0mm, 2mm, 4mm away from the center of the implants.
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본 논문에서는 현재 진행 중인 인공 슬관절 연구에서 역학적 분석분야의 동향과 접촉 응력해석에 대하여 언급한다. 인공 관절 특히 슬관절은 인체에서 가장 크고 움직임이 복잡하여 인공 관절 설계가 어려우며 또한 이에 대한 생체역학적 실험이 쉽지 않다. 무엇보다도 외국에서 연구가 활발하고 제품 생산도 선진국에서 주도하고 있으며 그 기술 격차는 매우 큰 현실이다. 최근까지 발표된 논문과 특히 실험과 수치해석이 병행되어 우수한 결과가 발표된 논문 내용을 중심으로 역학 분야를 소개하고자 한다. 접촉 유한요소해석이 수행된 내용도 일부도 포함된다.
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Rigorous FE(Finite Element) analyses of the cable-stayed bridge with steel-box girder, the main construction method of which is FCM (Free Cantilever Method), are presented in this paper. The analysis and the checking of design for a derrick crane under several loading conditions are performed using the software MIDAS/Civil and the beam elements are used to model the main structure. Among all the construction stages, special construction stages are chosen and considered to ensure the safety of segments of box girder The stress analysis for lifting of a segment of box girder is performed using the software SAP2000 and the shell elements of which having 6 DOF(Degrees Of Freedom) per nodes are successfully used to model the segment of box girder for the purpose of capturing the detailed behaviors on the folded-plates in the segment. Finally, concluding remarks are given to improve a design of the derrick crane and the segment based on the results from this study.
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This paper presents the estimation of buckling coefficients and an ultimate strength for a longitudinally profiled plate (LP plate). From the buckling analysis of the LP plate compressed in one direction, the buckling coefficients for the thickness ratio are obtained by Rayleigh-Ritz method and Galarkin method. This paper also provides the technique of a finite element analysis considering the residual distributions of residual stresses and forces equilibrium in the LP plate. The strength behavior of the LP plate obtained from the analysis shows that the ultimate strength differs from the strength which is calculated from the current design code. Based on the results, this paper presents some new proposals about the strength evaluations of the LP plate.
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For bridge-vehicle interaction analysis of cable-supported brides, the superposition method is applied based on the results of 3-dimensional free vibration analysis using General-purpose FEM Software. This study firstly performs the eigenvalue analysis for the free vertical and the torsional vibration of bridges using FEM analysis. Next the equations of motion considering interaction between bridges and vehicles/train are derived from mode superposition method. And then dynamic analysis is performed using the Newmark numericial method. Finally through the numerical examples, the dynamic responses of cable-supported bridges by this study are presented and discussed.
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The design of structural engineering optimization is to minimize the cost. This problem has many objective functions formulating section and shape as a function of the included discrete variables. simulated annealing, genetic algerian and TABU algerian are searching methods for optimum values. The object of this reserch Is comparing the result of TABU algorithm, and verifying the efficiency of TABU algorithm in structural optimization design field. For the purpose, this study used a solid truss of 25 elements having 10 nodes, and size optimization for each constraint and load condition of Geodesic ome, and shape optimization of Cable Dome for verifying spatial structures by the application of TABU algorithm.
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제철용 고로구조물의 안전성 위협 요인으로는, 고로자중이나 철광석 낙하 둥과 같은 기계하중 외에도 구조물 내부 온도가 최대
$1700^{\circ}C$ 에 이르는 고온 환경을 들 수 있다. 이러한 고온의 작업 환경은 고로 구성부재들의 크립손상, 열피로 문제 등을 야기시키기 때문에 이들 고열에 의한 영향평가는 고로의 안전성 평가에 있어 필수요소로 거론되고 있다. 일반적으로 고로의 단면을 구성하고 있는 내화재, 냉각판, 철피 등의 냉각시스템을 거치면서 내부의 고온 환경은 고로 외피에 이르는 동안 온도강하가 이루어진다. 급격한 온도강하는 나타나지 않지만 장기간 고로 가동에 있어 상시하중으로 작용하는 이 열원에 의해 고로 각 구부위에는 열응력이 발생하고 이 열응력과 나머지 기계적 하중의 조합에 의해 크립이나 열피로 등과 같이 고로 구조물 안전성 위해요인들이 발생한다고 분석되어 진다. 따라서 본 연구에서는, 고로 안전성 평가를 위한 첫 번째 단계로서 범용유한요소해석 프로그램인 ANSYS를 이용한 열응력 해석을 수행하여 잠재적인 안전성 위해요인으로 알려진 열응력 발생 특성을 분석하고, 고로 건전설계 및 보수 유지 관리지침으로 활용할 수 있는 기반기술을 개발한다. -
본 해석은 제철용 고로 구조물에 대해여 고로 내의 온도 분포를 이용한 열전도 유한요소 해석을 수행하고자한다. 해석모델인 고로는 내화벽돌, 냉각판, 내화재(castable), 철피의 복잡한 구조로 이루어져있다. 각각의 재료뿐만 아니라 고로에 사용되어지는 모든 내화벽들의 재료 물성치 값을 사용하여 보다 실직적인 해석을 수행하고자 하며 고로의 냉각 시스템인 냉각판과 냉각 pipe의 효과 규명하고자 한다. 어떠한 부분 모델이 아니라 고로 전체를 대상으로 열전도 해석을 수행한다.
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The freeplay, one of the concentrated structural nonlinearities, is inevitable for control surfaces of a real air vehicle due to normal wear of components and manufacturing mismatches. Also aerodynamic nonlinearities caused by a shock wave occur in transonic region. In practice, these nonlinearities induce the limit cycle oscillation (LCO) and decrease the transonic flutter speed. In this study, the fictitious mass method is used to apply a modal approach to nonlinear structural models due to freeplay. The transonic small-disturbance (TSD) equation is used to calculate unsteady aerodynamic forces in transonic region. Nonlinear aeroelastic time responses are predicted by the coupled time integration method (CTIM). This method was also applied to a 3D all-movable control wing to investigate its nonlinear aeroelastic responses. The angle of attack effect on the LCO characteristics has been found to be closely related with the initial pitching moment.
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In this study, we implement a framework that directly links a general tensor-based shell finite element to NURBS geometric modeling. Generally, in CAD system the surfaces are represented by B-splines or non-uniform rational B-spline(NURBS) blending functions and control points. Here, NURBS blending functions are composed by two parameters defined in local region. A general tensor-based shell element also has a two-parameter representation in the surfaces, and all the computations of geometric quantities can be performed in local surface patch. Naturally, B-spline surface or NURBS function could be directly linked to the shell analysis routine. In our study, we use NLib(NURBS libraray) to generate NURBS for shell finite analysis. The NURBS can be easily generated by interpolating or approximating given set of data points through NLib.
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In this paper, we develop continuum-based design sensitivity analysis (DSA) methods using both direct differential method (DDM) and adjoint variable method (AVM) for non-shape design problems. The developed DSA method is further utilized for the topology design optimization of 3-dimensional structures. In numerical examples, the analytical DSA results are verified using finite difference ones. The topology optimization method yields very reasonable results in physical point of view.
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Korean shipyards have accumulated a great amount of data. But they do not have appropriate tools to utilize the data in practical works. Engineering data contains experts' experience and know-how In its own. It is very useful to extract knowledge or information from the accumulated existing data by using datamining technique. This paper treats an evolutionary computation method based on genetic programming (GP), which can be one of the components to realize datamining.
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In this paper, using an adjoint variable method, we develop a design sensitivity analysis (DSA) method applicable to 3-Dimensional heat conduction problems in steady state. Also, a topology design optimization method is developed using the developed DSA method. Design sensitivity expressions with respect to the thermal conductivity are derived. Since the already factorized system matrix is utilized to obtain the adjoint solution, the cost for the sensitivity computation is trivial. For the topology design optimization, the design variables are parameterized into normalized bulk material densities. The objective function and constraint are the thermal compliance of structures and allowable material volume, respectively, Through several numerical examples, the developed DSA method is verified to yield efficiency and accurate sensitivity results compared with finite difference ones. Also, the topology optimization yields physical meaningful results.
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Using higher order Mindlin plates and piezoelectric materials, eigenvalue problems are considered. Since piezoelectric crystal resonators produce a proper amount of electric signal for a thickness-shear frequency, the objective is to decouple the thickness-shear mode from the others. Design variables are the bulk material densities corresponding to the mass of masking plates for electrodes. The design sensitivity expressions for the thickness-shear frequency and mode shape vector are derived using direct differentiation method(DDM). Using the developed design sensitivity analysis (DSA) method, we formulate a topology optimization problem whose objective function is to maximize the thickness-shear component of strain energy density at the thickness-shear mode. Constraints are the allowable volume and area of masking plate. Numerical examples show that the optimal design yields an improved mode shape and thickness-shear energy.
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A constitutive model was implemented in ABAQUS code. The constitutive equation can model the behavior for overall range of strain level from small to large deformation, which is based on anisotropic hardening rule and total stress concept. The formulation includes (1) finite strain formulation on the basis of Jaumann rate, (2) implicit stress integration and (3) consistent tangent moduli. Therefore the mathematical background was established in order that large deformation analysis can be performed accurately and efficiently with the anisotropic constitutive model. In the large deformation analyses, geometric nonlinearity was considered and the result of analyses with the proposed model was compared with that of Mises model for the overall strain range behavior.
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Many methods have been developed and are in use for structural size optimization problems, In which the cross-sectional areas or sizing variables are usually assumed to be continuous. In most practical structural engineering design problems, however, the design variables are discrete. This paper proposes an efficient optimization method for structures with discrete-sized variables based on the harmony search (HS) meta-heuristic algorithm. The recently developed HS algorithm was conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary In this paper, a discrete search strategy using the HS algorithm is presented in detail and its effectiveness and robustness, as compared to current discrete optimization methods, are demonstrated through a standard truss example. The numerical results reveal that the proposed method is a powerful search and design optimization tool for structures with discrete-sized members, and may yield better solutions than those obtained using current method.
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Most engineering optimization are based on numerical linear and nonlinear programming methods that require substantial gradient information and usually seek to improve the solution in the neighborhood of a starting point. These algorithm, however, reveal a limited approach to complicated real-world optimization problems. If there is more than one local optimum in the problem, the result may depend on the selection of an initial point, and the obtained optimal solution may not necessarily be the global optimum. This paper describes a new harmony search(HS) meta-heuristic algorithm-based approach for structural size optimization problems with continuous design variables. This recently developed HS algorithm is conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary. Two classical space truss optimization problems are presented to demonstrate the effectiveness and robustness of the HS algorithm. The results indicate that the proposed approach is a powerful search and optimization technique that may yield better solutions to structural engineering problems than those obtained using current algorithms.
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The use of system identification approaches for damage detection has been expanded in recent years. Soft computing techniques such as neural networks have been utilized increasingly. Damage assessment using neural networks is presented in this study. Data set for training neural networks are acceleration response of simple beam under the various damage states ,which are the inputs. The outputs are the damage locations and extents. Not only the trained damages but also untrained damages are. detected accuratelyintheassessmentstage.
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In this paper, a practical control method of wind-induced vibration of high-rise buildings is presented in the form of resizing algorithm. In the structural design process for high-rise buildings, the lateral load resisting system for the building is more often determined by serviceability design criteria including wind-induced vibration level. Even though many drift method have been developed in various forms, no practical design method for wind induced vibration has been developed so far. Structural engineers rely upon heuristic or experience in designing wind induced vibration. The performance of the proposed method is evaluated by comparing wind-induced vibration levels estimated both from approximate techniques and wind tunnel test.
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This research is to develop a seismic response analysis method for a spent fuel storage cask. FEM model is built for the test model of 1/8 scale spent fuel dry storage cask using available 3D contact conditions in ABAQUS/Explicit. Input load for this analysis os a seismic wave of El-centro earthquake, and the friction and damping coefficients in the analysis condition we obtained from the test result. Penalty and kinematic contact methods of ABAQUS are used for mechanical contact formulation. The analysis method was verified for rocking angle obtained by seismic response tests. The kinematic contact method with an adequate normal contact stiffness showed a good agreement with tests.
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The purpose of this study is to suggest some references of maintenance and design of concrete gravity dams by analyzing dynamic characteristics in x, y, z directions. It is considered as additional mass, soil interaction for numerical dynamic analysis for gravity concrete dams in Han River basin as some cases. The result shows that the overflow structure can be possibly underestimated for the evaluation of the seismic performance using seismic intensity, modified seismic intensity methods. A much more research is still necessary for the evaluation of comprehensive seismic performance of concrete gravity dam
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The reinforcing effect of modified structure of PSC beams is analyzed in this study. The PSC beams are closed by precast half panels embeding PS tendons at the bottom flange of I-bear The stiffness of box structure is larger and the PS force at half panels makes a time-dependent upward camber of superstructures. The superstructure becomes a second composite structure among 3 elements-PSC ben RC slab, PSC Panel. The time-dependent creep and shrinkage effect at PSC Panels and structural behavior is verified considering construction sequences. The optimal range of to-box reinforcing method is surveyed through reliability analysis.
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Existing results of some related experiments report that variation in the magnitude of prestressing force may leads to a change of dynamic properties of a PSC girder system. Since a usual dynamic equilibrium equation doesn't explain these phenomena, a modified dynamic equilibrium equation is derived in this paper by considering prestressing force as an internal energy of the system. The derived equation is applied to a modified beam element model is proposed. The proposed model validated by comparing the natural frequencies computed by the model with those from an existing experiment result.
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Concrete are brittle materials and they are which come to brittle fracture rapidly by progress of cracks. Therefore, what the time for repairing the damage portion is understands importantly by such cracks. When they happened the glass pipe similar to concrete was used. Such a glass pipe can insert repair material in an inside, or can use it by switch. They are interested in the crack monitoring of structure using FM radio sensor and PZT sensor. In this study, the monitoring to a crack was studied using FM radio sensor and PZT sensor. Therefore, the purpose of this study is the fundamental research which detects damages of main members using the compound sensor which consisted of the radio sensors of resistance, PZT, and FM system.
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It is limited to decrease height or section even by system conversion to indeterminate structure - continuous beam - in existing PSC girder bridges. In this study, the movement of connection is analyzed through actual field test, by increasing stiffness of negative moment area in continuous PSC bridge and developing continuous PSC bridge with embedded steel plate, that can overcome the demerit of existing connection. As a result, it is confirmed that the body unification of the connection is being realized and maintained. Moreover, the height of a span is suggested in continuous PSC girder bridge with embedded steel plate by computational analysis
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This paper describes a reinforced concrete crack model, which utilizes a strain decomposition technique. The strain decomposition technique enables the explicit inclusion of physical behavior across the cracked concrete surface such as aggregate interlock and dowel action rather than intuitively defining the shear retention factor. The proposed concrete crack model is integrated into the commercial finite element software ABAQUS shell elements through a user-supplied material subroutine. The FE results have been compared to experimental results reported by other researchers. The proposed bridge FE model is capable of predicting the initial cracking load level, the ultimate load capacity, and the crack pattern with good accuracy.
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In this study, strain measurement and its applicability to estimated deflection curve using fiber bragg grating sensors was conducted. For this purpose, reinforced concrete beams were made and sensors were attached both on the surface of the beams and inside steel. Two types of sensors were used to detect strain on the beams and steel : fiber bragg grating sensors, electric resistance strain sensors. So fatigue test is done with measuring strain of specimen. In addition, this experiments estimates the optimum deflection curve that converts strain curve data measured by FBG sensors into deflection.
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In this paper, an analytical model for estimation of the time at which the concrete surface begins to dry is introduced to predict whether or not plastic shrinkage cracks occur. First of all, the validity of a consolidation model for bleeding of cement paste proposed by Tan et al. is verified by comparing the analytical results with the experimental results, and used to evaluate the rate and amount of bleed water of concrete. Also an analytical model for evaporation of bleed water which considers the effect of the temperature variation of concrete surface due to hydration heat on the evaporation rate is proposed, and the experimental and analytical results are then compared to verify the validity of the introduced model. In advance, the time at which the concrete surface begins to dry is estimated using above two analytical models, and compared with the experimental results about the time at which plastic shrinkage cracks occur. From the comparison, it is verified that the proposed model can predict the occurrence of plastic shrinkage cracking with comparative precision.
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An analytical procedure to analyze reinforced concrete (RC) beams subject to monotonic loadings is proposed on the basis of the moment-curvature relations of RC sections. Unlike previous analytical models which result the overestimation of stiffnesses and underestimation of structural deformations induced from ignoring the shear deformation and assuming perfect-bond condition between steel and concrete, the proposed relation considers the rigid-body-motion due to anchorage slip at the fixed end. The advantages of the proposed relation, compared with the previous numerical models, are on the promotion in effectiveness of analysis and reflection of influencing factors which must be considered in nonlinear analysis of RC beam by taking into account the nonlinear effects into the simplifying moment-curvature relation. Finally, correlation studies between analytical and experimental results are conducted to establish the applicability of the proposed model to the nonlinear analysis of RC structures.
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The numerical analysis is carried out to identify the influence of design factors to shear capacity of cast-in-place (CIP) anchor in ACI 349 Code that is available for the design of fastening system at Nuclear Power Plant (NPP) in this study. The MASA program is used to develop the numerical analysis model and the developed numerical analysis model is verified on a basis of the various test data of CIP anchor. Both
$l/d_o$ and$c_1/l$ we considered as design factors. As a result, the variation of$l/d_o$ has no influence on the shear capacity of CIP anchor but$c_1/l$ has a large influence on the shear capacity of CIP anchor, Therefore, it is proved that ACI 349 Code may give a non-conservative results compared with real shear capacity of CIP anchor according to$c_1/l$ . -
Geometrical non-linearity due to the flexibility of cables must be considered efficiently in the dynamic analysis of cable structures. In this paper, formulation of tangent stiffness matrix of elastic catenary cable is derived by using relative nodal displacements, self-weight and unstressed cable length. Free vibration analysis of simply supported cable using elastic catenary cable elements is conducted and compared with that using truss elements. The result shows that elastic catenary cable elements are more compatible than truss elements in the case of analysis of cable structures. Furthermore, the characteristic of dynamic behaviors of cable structures by temporary unstability phenomenon is confirmed.
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This study presents a elastic parabolic cable element for initial shaping analysis of cable structures. First, the compatibility condition and the tangent stiffness matrices of the elastic catenary cable element are shortly summarized. Next the force-deformation relations and the tangent stiffness matrices of the elastic parabolic cable elements are derived from the assumption that sag configuration under self-weights is small. To confirm the accuracy of this element, initial shaping analysis of cable-stayed bridges under dead loads is executed. Finally, the accuracy and the validity of the analysis-results are compared and analyzed through numerical examples.
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In this paper, the feasibility of the high-performance damping device vibration suppression of stay cables has been investigated. The proposed damping system consists of a linear viscous damper and a scissor-jack-type toggle linkage. Since the mechanism of the scissor-jack-type toggle linkage amplifies the relative displacement of the linear viscous damper, it is expected that the capacity of the viscous damper used in the scissor-jack-damper energy dissipation system can be reduced without the loss of the control performance. Numerical simulation results demonstrate the efficacy of the damping system employing the scissor-jack-type toggle linkage. Therefore, the proposed damping system could be considered as one of the promising candidates for suppressing vibration of stay cable.
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Stay cables, such as are used in cable-stayed bridges, are prone to vibration due to their low inherent damping characteristics. Several methods have been proposed and implemented to mitigate this problem, though each has its limitations. Recently some studies have shown that active and semiactive control system using MR (Magnetorheological) damper can potentially achieve both higher performance levels than passive control system and adaptability with few of the detractions. However, a control system including a power supply, controller, and sensors is required to maximize the performance of the MR damper and this complicated control system is not effective to most of large civil structures. This paper proposes a smart passive damping system using MR dampers by introducing electromagnetic induction (EMI) system as an external power source to MR damper and verified the performance of smart passive damping system for mitigating the vibration of stay cables. The performances of smart passive damping system are compared with those of linear viscous damper and passive-mode MR damper.
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Analysis program to estimate the dynamic characteristics of bridge is investigated by using three-dimensional analytical model considering vehicle-bridge interaction. A dynamic interaction models of the vehicle-bridge system are established, which is composed of a vehicle element model and a finite element bridge model. The vehicle models are established according to the structure and suspending properties of vehicle. The dynamic responses of the bridge are calculated. But the computer simulation program is being verified with field tests results, it must be corrected according to them.
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In this paper a study on the characteristics and the reduction method for the ground vibration due to traveling tilting car are carried out. The transmitted load which induces the ground vibration is computed through a study on the interaction between tilting car and the line. Then, this load is applied into the numerical model, which is designed considering the diverse ground conditions and tunnels. Through the numerical analysis according to the conditons, the characteristics and the reduction method for the ground vibration by tilting car are studied.
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In this paper, three dimensional dynamic infinite elements are developed for the soil-structure interaction analysis in multi-layered halfspace. For the efficient discretization of 3-D for field regions, five types of dynamic infinite elements are developed. They are the horizontal, vertical, horizontal comer, vertical comer and horizontal/vertical corner infinite elements. The shape functions of the infinite elements are based on approximate expressions of analytical solutions of propagating waves in the infinite region. Numerical example analyses are presented for compliances of rigid circular and square plates to demonstrate the effectiveness of the proposed infinite elements.
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This paper proposes the shaking table testing method, without any soil specimen only using building model as an experimental part, considering dynamic soil-structure interaction based on the substructure method. The two-layered soil is assumed as a soil model of the entire soil-structure interaction syhstem(SSI) in this paper. Differently from the constant soil stiffness, the frequency-dependent dynamic soil stiffness is approximated for the case of both acceleration and velocity feedback, respectively. The interaction force is observed from measuring the accelerations at superstructure. Using the soil filters corresponding to the approximated dynamic soil stiffness, the shaking table drives the acceleration or velocity, which the needed motion to give the building specimen the SSI effects. Experimental results show the applicability the proposed methodologies to the shaking table test considering dynamic soil-structure interaction.
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This paper presents the shaking table testing method, only using building specimen as an experimental part taking into account the dynamic soil-structure interaction based on the substructure method. The Parmelee's soil stiffness is used as an assumed soil model in here. The proposed methodologies are summarized as: (1) Acceleration feedback method is the one that the shaking table is driven by the motion, corresponding to the acceleration at foundation of the total SSI system. This is found by observing the fed-back accelerations of superstructure and using the interaction force based on the acceleration formulation. (2) Velocity feedback method is the one that the shaking table is driven by the motion, corresponding to the velocity at foundation of the total SSI system. This is found by observing the fed-back accelerations of superstructure and using the interaction force based on the velocity formulation. The applicability of the proposed methodologies to the shaking table test is investigated and experimentally verified in this paper.
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Since soil-structure interactions are one of the most important subjects in the structural/foundation engineering, much study concerning the soil-structure interactions had been carried out. One of typical structures related to the soil-structure interactions is the strip foundation which is basically defined as the beam or strip rested on or supported by the soils. At the present time, lack of studies on dynamic problems related to the strip foundations is still found in the literature. From these viewpoint, this paper aims to theoretically investigate dynamics of the elliptic strip foundations and also to present the practical engineering data for the design purpose. Differential equations governing the free, out-of-plane vibrations of such sap foundations we derived, in which effects of the rotatory and torsional inertias and also shear deformation are included although the warping of the cross-section is excluded. Governing differential equations subjected to the boundary conditions of free-free end constraints are numerically solved for obtaining the natural frequencies and mode shapes by using the numerical integration technique and the numerical method of non-linear equation.
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This paper proposed a new substructural identification method to estimate the bending stiffness of a bridge deck, a fundamental structural health index of a super-structure. The proposed method can estimate the bending stiffness without considering actual supporting conditions by using substructural identification method while most of conventional methods need reasonable assumptions on supporting conditions which are hard to be assessed in a real bridge in operation. The mathematical formulation is derived and the results of laboratory tests are summarized. It was verified that the proposed method gives consistent estimation results regardless of actual supporting conditions.
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Two-plate girder bridge and narrow steel box girder bridge are suggested for the steel wheel AGT system. For these bridge system, rail-bridge interaction analysis was carried out and dynamic behavior of these bridges was investigated. The result shows that all the estimated parameters satisfy the criteria concerned. As a result these two suggested bridge systems have enough performance to be competitive for the LRT elevated structures.
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Wind Turbines of big scale of modem stage are made of a part glass F.R.P. Carbon Reinforced Plastic and Kevlar can be used 0 reinforcement but those are not economical in big scale of Wind Turbines. In this study life sized 10kW-class Rotor Blade is made of F.R.P. which is high stiffness and good dynamic behavior characteristic for light weight. It is accomplished an experimental research of Bending analysis blade. Bending analysis blade are calculated with F.E. Analysis performed with commercial F.E.M program ANSYS. Finally, experimental research is compared with F.E. Analysis. The results indicate that experimental values have good agreements with the F.E. Analysis.
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The ship plating is generally subjected to combined in-plane load and lateral pressure loads. In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion of the vessel. Lateral pressure is due to water pressure and cargo. These load components are not always applied simultaneously, but more than one can normally exist and interact. Hence, for more rational and safe design of ship structures, it is of crucial importance to bitter understand the interaction relationship of the buckling and ultimate strength for ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.
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Ship have cutout inner bottom and girder and floor etc. Ship's structure is used much, and structure strength must be situated, but establish new concept when high stress interacts sometimes fatally the area. There is no big problem usually by aim of weight reduction, a person and change of freight, piping etc.. Because cutout's existence grow up in this place, and elastic buckling strength by load causes large effect in ultimate strength. Therefore, stiffened perforated plate considering buckling strength and ultimate strength is one of important design criteria which must examine when decide structural concept at initial design. Therefore, md, reasonable buckling strength about stiffened perforated plate need to ultimate strength limited design . Calculated ultimate strength varied several web height and cutout's dimension, and thickness in this investigated data. Used program(ANSYS) applied F.E.A code based on finite element method
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Welding deformations are affected by various factors. This research investigates effects of welding sequence and self-weight on welding deformation. According to the results by equivalence load method, magnitude of welding deformation with self-weight is about twice one without self-weight on parallel weld path component. But welding deformation with the components used in this research are not affected by welding sequence
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In this study ship collision risk analysis is performed to determine the design vessel for collision impact analysis of the bridge. Method I in AASHTO LRFD bridge design specifications is a semi-deterministic analysis procedure for determining the design vessel. Method ll which is a more complicated probability based analysis procedure is used to select the design vessel for collision impact. The AF allocation by weights seems to be more reasonable than the pylon concentration allocation method because AF allocation by weights takes the design parameter characteristics quantitatively into consideration although the pylon concentration allocation method brings more economical results when the overestimated design collision strength of piers compared to the strength of pylon is moderately modified. Therefore more researches on the allocation model of AF and the selection of design vessel are required.
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An initial member sections of steel structures is selected by experience of expert building structural designers. And appropriate member section is designed by repeat calculation through structural analysis. Therefore an initial assumption of member section is necessary for saving the time for structural design and is important to acquire safety of building structures. Also brace damper are generally used to prevent or decrease structural damage by its hysteretic behavior in building structures subjected to strong earthquake. Based on plastic design, the initial section of members for architectural steel structures with brace hysteretic dampers is presented and seismic effect of structural behavior by the ratio of damper stiffness to structural story stiffness is estimated in this paper.
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The earthquake-resistant structural systems have to ensure the sufficient stiffness and ductility for the stability For those purposes, recently, the seismic isolation system to reduce earthquake energy has been used. So, it is necessary to examine the characteristics of dynamic behavior of spatial structures governed by higher modes rather than lower modes different from the cases of high rise buildings. The objectives of this paper are to inspect the efficiency of the equivalent model method according to the various earthquake loads and half-open angles. Moreover it is examined the dynamic behaviors according to change the mass and the stiffness of sub-structures as a fundamental study of performance design for the spatial structures. Finally, seismic isolation system is applied to boundary parts of roof system and sub-structure to obtain the target performance.
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Recently, performance based seismic design (PBSD) methods have been suggested in numerous forms and widely studied as a new concept of seismic design. The PBDSs are far from being practical method due to complexity of algorithms resided in the design philosophy. In this paper, optimal seismic design method based on displacement coefficient method (DCM) described in FEMA 273 is developed. As an optimizer simple genetic algorithms are used for implementations. In the optimization problem formulated in this Paper, strength design criteria stiffness design criteria, and nonlinear response criteria specified in DCM are included in design constraints. The optimal performance based design(OPBD) method is applied to seismic design of a 3-story two-dimensional steel frame structures.
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The purpose of this paper is to compare the control effect of toggle brace system having amplifying displacement mechanism with that of conventional brace system when the identical MR damper is applied to each system. The force-displacement and lone-velocity relationships of MR damper are obtained using harmonic load test and the analytical model for MR damper is presented. White noise excitation tests of a single degree of freedom system with MR-toggle brace system and MR-chevron system are conducted and the transfer functions of the systems are compared. Test results show that the control effect of the toggle system is superior to that of the conventional brace system.
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Even in moderate to low seismic regions like Korean peninsular where wind loading usually governs the structural design of a tall building, the probable structural impact of the design basis earthquake or the maximum credible earthquake on the selected structural system should be considered at least in finalizing the design. In this study, by using response spectrum analysis and linear time history analysis method, seismic performance evaluation was conducted for wind-designed concentrically braced steel highrise buildings. Both spectrum-compatible artificial accelerograms and recorded accelerograms were used as input ground motions for the time history analysis. The analysis results showed that wind-designed concentrically braced steel highrise buildings possess significantly increased elastic seismic capacity due to the system overstrength resulting from the wind-serviceability criterion and the width-to-thickness ratio limits on steel members. Time history analysis results generally tended to underestimate the seismic response as compared to those of response spectrum analysis.
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Distributed operation of overall structural design process, by which product and process optimization are implemented, is presented in this paper. The database-interconnected multilevel hybrid method, in which the conventional design method and the optimal design approach are combined, is utilized there. The method selectively takes the accustomed procedure of the conventional method in the conceptional framework of the optimal design. Design conditions are divided into primary and secondary criteria This staged application of design conditions reduces the computational burden for large complex optimization problems. Two kinds of numeric and graphic processes, are simultaneously implemented on the basis of concurrent engineering concepts in the distributed environment of PC networks. Numerical computation on server and graphic works on independent client are communicated through message passing. Numerical design is based on the optimization methodology and the drawing process is carried out by AutoCAD using the AutoLISP programming language. The prototype design experimentation for some steel trusses shows the validity and usability of the method. This study has sufficient adaptability and expandability in methodology, in that it is based on general theory and industry standard systems.
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Damage detection is a very active research field, in which significant efforts have been invested in recent years. In this paper, analysis using structural stiffness estimation for damage detection is presented and compared to other methodologies. By using a cantilever analytical beam model, it is shown here that not only location but also the amount of damage in structure can be predicted from the ratio of change in stiffness. Damage detection experiment in real beam specimen on is also peformed and the results are compared.
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This study presents a schema matching technique which can be applied to XML semantic model of structural calculation reports of steel-box bridges. The semantic model of structural calculation documents was developed by extracting the optimized common elements from the analyses of various existing structural calculation documents, and the standardized semantic model was schematized by using XML Schema. In addition, the similarity measure technique and the relaxation labeling technique were employed to develop the schema matching algorithm. The former takes into account the element categories and their features, and the latter considers the structural constraints in the semantic model. The standardized XML semantic model of steel-box bridge's structural calculation documents called target schema was compared with existing nonstandardized structural calculation documents called primitive schema by the developed schema matching algorithm Some application examples show the importance of the development of standardized target schema for structural calculation documents and the effectiveness and efficiency of schema matching technique in the examination of the degree of document standardization in structural calculation reports.
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The aim of this study is to develop a procedure to estimate the wind loads from the accelerations of a tall building structure. The wind loads may be directly calculated using the inverse analysis or simply integrating the wind pressures of the overall structure. But, these methods are too expensive and impossible to implement in some cases. In this study, a simple method is proposed to estimate the wind loads using the Kalman filter. This method is very stable compared to the direct integration of the acceleration to get the velocity or displacement. The proposed method is verified thorough numerical analysis, and results show that the proposed method is robust and estimates the wind loads accurately.
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Recently, the collision problems between a bridge and a navigating ship are frequently issued at the stage of structure design. Even the many study results about vessel to vessel collision are presented, but the collision studies between vessel and bridge structure have been hardly presented. In this study, nonlinear dynamic analysis of vessel and fender system carry out using ABAQUS/Explicit commercial program with consideration of some parameters, such as bow structure we composed to shell element also ship's hull is modeling to beam element. Also, buoyancy effect is considered as spring element. The two types of fender systems was comparable with both collision analysis about steel materials fender system and rubber fender system On the purpose of study is analyzed the plasticity dissipated energy of vessel and fender system. We blow characteristic that kinetic energy is disappeared by plastic large deformation in case of collision. Also, We considered dissipated kinetic energy considering friction effect.
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Recently Life Cycle Cost Analysis for civil infrastructures such as pavements, bridges, and dams has been emphasized However, so far, there are few systems available for life cycle cost analysis of bridges at design stage. Therefore, the objective of this paper is to develop a user-friendly life-cycle cost analysis system for LCC-effective optimal design decision making at design stage. The program is based on the proposed LCC model, formulation, analysis modules and systematic procedure that suit Korean construction conditions. It is expected that the developed system can be effectively utilized for more LCC-effective design of bridges. It is applied to an actual bridge design project in order to demonstrate its effectiveness and applicability.
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In this study, a translator for transferring structural analysis data among commercial structural analysis programs was developed. The translator adopted the neutral format type based on ISO standard STEP AP 209 not only for the international standardization and robustness but also for the efficient management of structural analysis data Additional load entity is developed and added to AP 209 for the prevention of loss of information in retrieving exact loading condition. A modulization which is needed for efficient management and extension of the translator was made for the encapsulation of file format of each commercial code. Pilot tests peformed with 3-D frame analysis data of Sung-su bridge show that the developed translator guarantees the integrated management of analysis information as well as the exact transferring and retrieving of analysis data and related information.
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The optimal design was performed for the bridge superstructure composed of steel box girders and concrete deck considering life cycle cost. The service life of the superstructure was estimated, after load carry capacity curves for steel girder and concrete deck were derived on the basis of condition grade curves and maintenance histories. The object function was determined as life cycle cost, including initial cost, total maintenance cost, disposal cost and user cost, for a period of the estimated service life. The optimal design of the superstructure was performed for the various service lifes. The annual costs were used to compare calculated results and to get the most economical design. Also this paper presents reasonable idea for the use of user cost with uncertainty.