Many studies showed that small imperfections can also have a considerable influence on the behaviour of structures. Especially, in Single-Layer Latticed Domes, initial imperfection occurred by human error and construction error is very important to the buckling load. The definition of imperfection is that a node of structure shifts from perfect condition. For example, in the case of truss structures, imperfections are represented by shifting the location of nodal points relative to the position in which they would be for a perfect structure. This paper uses Arc-length Method in nonlinear iteration analysis, choosing star dome, in which many studies have been accomplished, as a model. The results of analysis show that initial imperfection can reduce the buckling load of structures.

The primary objective of this paper is to grasp many characteristics of buckling behavior of latticed spherical domes under various conditions. The Arc-Length Method proposed by E.Riks is used for the computation and evaluation of geometrically nonlinear fundamental equilibrium paths and bifurcation points. And the direction of the path after the bifurcation point is decided by means of Hosono's concept. Three different nonlinear stiffness matrices of the Slope-Deflection Method are derived for the system with rigid nodes and results of the numerical analysis are examined in regard in geometrical parameters such as slenderness ratio, half-open angle, boundary conditions, and various loading types. But in case of analytical model 2 (rigid node), the post-buckling path could not be surveyed because of Newton-Raphson iteration process being diversed on the critical point since many eigenvalues become zero simultaneously.

The main purpose of this paper is to investigate a more accurate behavior analysis of tapered column with initial imperfection. The nonlinear differential equations governing the deflected shapes of the tapered column with initial imperfection are derived by large deflection theory and solved numerically using the Runge-Kutta method and Regula-Falsi method. Three kinds of cross-sectional shape with simply supported end constraint are considered in numerical examples. The load versus displacement curves including the left and right end rotations are presented in figures. The effect of cross-sectional shapes on deflected shape is analyzed, and the deflected shapes of column for several initial imperfections are shown in figure.

배관을 구속시키기 위한 원통형 배관 지지대 (Trunnion Pipe Support)가 부착된 배관의 응력해석 을 위하여 유한요소해석을 사용하였다. 해석결과로 부터 얻어진 응력은 두께에 대한 평균 및 선 형 응력으로 분류 되었으며, 분류된 응력값은 압력에 의한 일차응력계수(B$_1$)와 이차응력계수(C$_1$), 모멘트에 의한 일차응력계수(B$_2$)와 이차응력계수(C$_2$)를 추정하기 위하여 ASME Code에 정의된 것과 일치하게 해석되었다. 무차원의 함수로써 응력계수에 대한 경험식을 개발하기 위하여 여러 모델의 해석을 수행하였다.

Three procedures are currently used for the design of deep beams, which are Empirical design method, Nonlinear analysis, and Truss models. The engineering logic and decisions inherent in these design procedures are dependent on the acquired knowledge and experience of the structural engineer. Knowledge-based system is useful to solve problems which require human experties. Therefore, this study presents an application of Knowledge-Based System for design of reinforced concrete deep beams with web openings.

An enhanced solution recovery method for recovering accurate derivatives such as moments, or shears, from finite element solutions for $C^{0}$ beam and plate is presented. In the enhanced method, the square of the residuals in the equilibrium equations is included. Results are compared with those of standard Zienkiewicz-Zhu methods. Numerical examples show that in the global projection, the enhanced technique improves the accuracy of projected solution significantly. In the local projection, the enhanced method circumvents the numerical ill-conditioning which occurs in some meshes, and usually recovers derivatives with better accuracy.y.

This paper deals with finite element analysis for incompressible viscous flow problem By formulating the governing equation based on the streamline upwind concept , the wiggle phenomenon of fluid flow is minimized in spite of a few number of finite element used. The penalty function method which can reduce the number of independent variables is adopted for the purpose of computational efficiency and the selected reduced integral is carried out for the convection and pressure terms to reserve the stability of solution. In time-history analysis of fluid flow, the accuracy and reliability of an obtained solution are established by using the predictor-corrector method. Finally, correlation studies between analytical and experimental results are conducted wi th the object ive to establish the validity of the proposed numerical approach.

In this study, an equivalent domain integral (EDI) method is presented to estimate the track-till integral parameter, J-value, for two dimensional cracked elastic bodies which may quantify the severity of the crack-tit) stress fields. The conventional J-integral method based on line integral has been converted to equivalent area or domain integrals by using the divergence theorem. It is noted that the EDI method is very attractive because all the quantities necessary for computation of the domain integrals are readily available in a finite element analysis. The details and its implementation are extened to both h-version finite element model with 8-node isoparametric element and p-version finite element model with high order hierarchic element using Legendre type shape fuctions. The variations with respect to the different path of domain integrals from the crack-tip front and the choice of 5-function have been tested by several examples.

Recently many efforts have been made to improve the efficiency of design and production of the structures using the automation system. But, this work has been progressed as independent or partial system. And, the study on the integrated system is not sufficient in application for practical problems yet. This paper deals with the fundamental concept of modeling system and application method on structural modeling. At first, the core of the integrated system is a shape modeling system that can represent the geometric and topological information. This system must be designed as an open system to be combined with each independent automation system. The appropriate concept to realize this system on structural modeling is object oriented modeling and this enables to integrate each automation system successfully, This concept was applied to automatic mesh generation. For shape modeling system, half-edge data structure that is being used in solid modeling was modified to handle the plate structure in the plane. And, to generate the triangular meshes, direct node connection method was used. And, as a result, the integrated system that generate the meshes of two dimensional structure automatically was realized. And, programmed by C++, these systems can be combined with other systems easily and have good reusability.

A boundary element method which utilizes the fundamental solution in the half plane is developed to analyze the multi-layered elastic media. The objective of this study is to derive numerically the fundamental solutions and to apply those to the exterior multi-layered domain problems. To obtain numerical fundamental solutions of multi-layered structural system, the same number of solutions as that of layers in Fourier transform domain are employed. The numerical integration technique is used in order to inverse the Fourier transform solution to real domain. To verify the proposed boundary element method, two examples are treated: (1) a circular hole near the surface of a half plane; and (2) a circular cavity within one layer of four layered half plane.

The stress intensity factor for an inter(ace crack in dissimilar elastic-elastic bimaterials is presented and the boundary element analysis is performed. It is shown that the proposed method produces the accurate and effective numerical results.

The stress intensity factor for an interface crack in dissimilar elastic and viscoelastic materials is derived and the time-domain boundary element analysis is performed. Numerical results show that the proposed method is very useful for the analysis of the interface crack in elastic and viscoelastic bimaterials.

In this paper, behaviour of underground structural systems due to excavation and change of groundwater level is analyzed using finite elements. Equilibrium equations based on the effective pressure theory and transient flow equations considering the groundwater level are derived. Integration equations are derived using Galerkin's approximation and time dependent analysis is employed to compute groundwater level change and pore pressures. This computed pore pressures are employed in equilibrium equations and then finally displacements and stresses are computed. The developed program is applied to analyze the behaviour of ground excavation below the groundwater level. The program is also applied to multi-step excavation at the same model. The results show that the displacements of the ground surface are much influenced by the change of the groundwater level. Therefore, it is concluded that the change of the groundwater level should be considered in order to analyze the behaviour of the underground structural systems accurately

Dynamic load models which show the practical behavior of truss bridge subjected to moving train load are presented. Three basically approaches are available for evaluating structural response to dynamic effects : moving force, moving mass, and influence moving force and mass. Simple warren truss bridge model is selected in this research, and idealized lumped mass system, modelled as a planar structure. In the process of dynamic analysis, the uncoupled equation of motion is derived from simultaneous equation of the motion of truss bridge and moving train load. The solution of the uncoupled equations of motion is solved by Newmark-$\beta$ method. The results show that dynamic response of moving mass and static analysis considering the impact factor specified in the present railway bridge code was nearly the same. Generally, the dynamic response of moving force is somewhat greater than that of moving mass. The dynamic load models which are presented by this study are obtained relatively adequate load model when apply to a truss bridge.

In this paper, a method of substructural identification is presented for the estimation of localized structural parameters. for this purpose, an auto-regressive and moving average with stochastic input (ARMAX) model is derived for the substructure to process the measurement data impaired by noises. The sequential prediction error method is used fer the estimation of unknown localized parameters. Using the substructural method, the number of unknown parameters can be reduced and the convergence and accuracy of estimation can be improved. For some substructures, the effect of the input excitation is expressed in terms of the responses at the inferences with the main structure, and substructural identification may be carried out without measuring the actual input excitation to the whole structure. Example analysis is carried out for idealized structural models of a multistory building and a truss bridge. The results indicate that the present method is effective and efficient for local damage estimation of complex structures.

In this paper, the effect of neglecting the own weight of the composite plate on the natural frequency of vibration of the laminated plates is presented. The method used has been developed by the author since 1974. This method is very effective for the plates with arbitrary boundary conditions and irregular sections. When the attached mass is equal to the weight of the plate, the effect of neglecting the plate weight is 9.26 percent

In this paper, a simple tut accurate method of vibration analysis of structural elements with or without attached mass/masses is presented. The method used has been developed by the senior author since 1974. This method is very effective for the plates with arbitrary boundary conditions and irregular sections. This method is applied to the special orthotropic Plate with two opposite edges simply supported and the other two opposite edges free. Such plate represents the most of the simply supported bridges/decks, including concrete and girders-cross beam systems. Detailed illustration is given for beams and plates for easy understanding. Some laminate orientation for which the special orthotropic equations can be applied are identified.

The ductility demand for seismic design of a single degree of structure or an individual structural member can be determined easily. However, there is no established method to determine the ductility demand far a structural system. The object of this paper is to develop a method for the estimation of the ductility demand far structural systems, in which the inelastic behavior can be taken into account properly. The validity of the proposed method has been examined far several cases with different structures and different earthquake excitations. The method is also compared with two alternative methods.

The differential equations governing free, out of plane vibrations of horizontally curved beams are derived and solved numerically to obtain the natural frequencies and the mode shapes. The Runge-Kutta method and Regula-Falsi method are used to integrate the differential equations and to determine the natural frequencies, respectively. In nu- merical examples, the hinged-clamped end constraint is considered and four lowest frequency parameters are reported as functions of four non-dimensional system parameters: (1) opening angle, (2) slenderness ratio, (3) shear parameter and (4) stiffness parameter. Also, typical mode shapes of displacements and stress resultants are shown.

Analyses of linear sloshing modes and seismic responses for cylindrical vessel containing fluid are performed by general finite element computer program, ANSYS. In order to examine the effectiveness of the sloshing analysis procedure, the calculated results are compared with experimental ones in the literature. Liquid sloshing effects in cylindrical LNG vessel are analyzed and the fluid-structure interaction effects are evaluated under the seismic loads. The sloshing frequencies calculated agree well with experimental results. The forces and moments for fixed and isolated LNG vessel are also calculated to evaluate the sloshing effects.

Recently, the response of a high-rise building to external dynamic force created by wind and earthquake has received much attention. This response is dependent on wind intensity, surrounding environment, building size, shape, mass, stiffness and amount of energy dissipation available in the system. The study has been done on these parameters. Attempts have been made to increase the damping in building system and thereby reduce structural response. These attempts have centered on adding an energy-dissipative system(passive tuned mass damper; passive TMD) to the building system and increasing the overall effective damping. In this paper the optimum condition of passive TMD will be derived with respect to random excitation and the properties of the optimum condition will have been studied.

In this study, a stochastic finite element model is proposed with a view to consider the uncertainty of physical properties of rock mass in the analysis of structural behavior on underground caverns. Here, the Latin Hypercube Sampling technique, in which can makeup weak points of the Monte Carlo Simulation, is applied for the analysis of underground cavern. The validity of the newly developed computer program has been confirmed in terms of verification examples. And, the applicability of the program to the field has been tested in terms of the analysis of the underground oil storage cavern in korea.

The focus of this study is on the problem of the design of structure of undetermined topology. This problem has been regarded as being the most challenging of structural optimization problems, because of the difficulty of allowing topology to change. Conventional approaches break down when element sizes approach to zero, due to stiffness matrix singularity. In this study, a novel nonlinear Programming formulation of the topology Problem is developed and examined. Its main feature is the ability to account for topology variation through zero element sizes. Stiffness matrix singularity is avoided by embedding the equilibrium equations as equality constraints in the optimization problem. Although the formulation is general, two dimensional plane elasticity examples are presented. The design problem is to find minimum weight of a plane structure of fixed geometry but variable topology, subject to constraints on stress and displacement. Variables are thicknesses of finite elements, and are permitted to assume zero sizes. The examples demonstrate that the formulation is effective for finding at least a locally minimal weight.

설계자는 설계를 진행시켜 가면서 많은 의사 결정을 내려야 한다. 그 결정은 크게 선택 결정과 타협 결정으로 나뉘어질 수 있다. 선택 결정은 여러 평가 기준을 고려해 여러 대안들 중 하나를 선택하는 결정이며 타협 결정은 제한 조건과 목표들을 가장 잘 만족하는 설계 대안의 주요 치수를 결정하는 것이다. 이때 두 결정의 결과는 설계자의 의사에 크게 의존하게 된다. 따라서 설계자의 의사를 체계적이고 정확하게 반영시켜줄 필요가 있다. AHP 기법은 불분명한 선택 문제에 있어서 문제를 계층적으로 분석하여 평가함으로써 설계자의 의사를 체계적으로 반영시켜줄 수 있다. 또한 정성적인 성질들을 정량적인 판단 기준에 따라 평가함으로써 설계자의 의사를 보다 일관적으로 반영할 수 있다. 보통 공학 문제의 경우 하나의 설계 대안을 선택하고 또한 그 대안의 주요 치수를 동시에 결정해야 하는 결합된 문제이다. 이때 선택에 필요한 각 대안의 속성이 타협 문제 변수들의 함수로 표현되기 때문에 최적 과정 중에 계속 변화하게 된다. 또한 여러 속성을 고려할 경우 자릿수와 단위가 모두 다르기 때문에 속성들의 평가가 표준적으로 이루어져야 한다. 이 부분에 학습된 인공 신경망을 도입함으로써 변화하는 속성치를 자동적으로 평가할 수 있으며 설계자의 의사와 경험적인 지식도 반영할 수 있게 되었다.

A number of typical type of steel-box pedestrian bridges are constructed in the metropolitan highway or heavy traffic urban area. Although it has the advantage of speedy construction because of its simple structural form and prefabricated erection method, it has been reported that many of these bridges are deteriorated or damaged and thus are in the state such that it would give unsafe and uncomfortable feeling to pedestrians. In the paper, for the realistic assessment of safety and residual earring-capacity of deteriorated and/or damaged steel box pedestrian bridges, an interactive non-linear limit state model are formulated based on the von Mises' combined stress yield criterion. It is demonstrated that the proposal model is effective for the reliability-based safety assessment and residual carrying-capacity evaluation of steel-box pedestrian bridges. In addition, this study suggests an effective and practical field load test method for pedestrian bridges.