재하속도에 따른 용접강관의 모멘트-곡률 거동특성에 관한 해석적 연구를 수행하였다. 3차원 열역학해석을 통하여 용접이음부의 잔류응력을 산출하였다. 그리고 동적소성모델이 적용된 탄소성 유한요소해석 프로그램을 이용하여 잔류응력을 고려한 용접강관(Welded pipe)의 동적해석을 수행하였다. 그리고 용접이음부가 없는 일반강관(Seamless pipe)에 대한 동적거동과의 비교를 통하여 해석을 수행하여 용접강관의 해석력과 해석결과는 용접강관의 모멘트가 일반강관의 모멘트에 비해 낮은 응답을 보였으나 재하속도가 증가함에 따라 모멘트 응답의 차이는 점차 감소하는 경향을 보였다.

Recently, as steel structures become higher and more long-spanned, application of high-strength steels is increasing gradually. However, criteria and example for design of high-strength steel are not built up. exiting criteria for structural steels is not proper for economical design of high-strength steel. Moreover, exiting criteria will be decrease the fatigue performance of steel bridge using high-strength steel. Therefore, criterion for application of high-strength steel must be established. In this paper, the behavior of plate girder using high-strength vertical stiffeners was clarified by carrying out layer elastic-plastic finite element analysis using finite deformation theory. In order to optimize the design and construction of plate girder using high-strength vertical stiffener, criterion for application of high-strength vertical stiffener is proposed.

Almost the steel bridges are manufactured and constructed by using weld process. The welding is necessary for connecting the flange, web and stiffener of steel bridges. However, residual stress and welding deformation producted by welding is a causes of decreasing the load carrying capacity of steel bridges. therefore, it is need to consider the initial stresses by welding when design the steel bridge. However, the influence of initial stress producted by welding on load carrying capacity of steel bridges is not elucidated. In this paper, the initial stress state on the flange, web and stiffener of steel bridges are clarified by carrying out 3-dimensional non-steady heat conduction analysis and 3-dimensional thermal elastic-plastic analysis. The influence of initial stress by welding on load carrying capacity of steel bridges is clarified by carrying out 3-dimensional elastic-plastic finite element analysis using finite deformation theory.

A three-dimensional (3-D) method of analysis is presented for determining the free vibration frequencies and mode shapes of solid paraboloidal and complete (that is, without a top opening) paraboloidal shells of revolution with variable wall thickness. Unlike conventional shell theories, which are mathematically two-dimensional (2-D), the present method is based upon the 3-D dynamic equations of elasticity. The ends of the shell may be free or may be subjected to any degree of constraint. Displacement components ur, uθ, and uz in the radial, circumferential, and axial directions, respectively, are taken to be sinusoidal in time, periodic in θ, and algebraic polynomials in the r and z directions. Potential (strain) and kinetic energies of the paraboloidal shells of revolution are formulated, and the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four digit exactitude is demonstrated for the first five frequencies of the complete, shallow and deep paraboloidal shells of revolution with variable thickness. Numerical results are presented for a variety of paraboloidal shells having uniform or variable thickness, and being either shallow or deep. Frequencies for five solid paraboloids of different depth are also given. Comparisons are made between the frequencies from the present 3-D Ritz method and a 2-D thin shell theory.

An exact solution procedure is formulated for the free vibration and buckling analysis of rectangular plates having two opposite edges simply supported when these edges are subjected to linearly varying normal stresses. The other two edges may be clamped, simply supported or free, or they may be elastically supported. The transverse displacement (w) is assumed as sinusoidal in the direction of loading (x), and a power series is assumed in the lateral (y) direction (i.e., the method of Frobenius). Applying the boundary conditions yields the eigenvalue problem of finding the roots of a fourth order characteristic determinant. Care must be exercised to obtain adequate convergence for accurate vibration frequencies and buckling loads, as is demonstrated by two convergence tables. Some interesting and useful results for vibration frequencies and buckling loads, and their mode shapes, are presented for a variety of edge conditions and in-plane loadings, especially pure in-plane moments.

속이 빈 축대칭 회전체인 두꺼운 쉘의 정확한 고유진동수와 모우드형상을 결정하기 위해서 3차원적인 해석방법이 사용되었다. 이 축대칭 회전쉘의 모선을 직선으로 한정하지 않았으며, 쉘의 두께 또한 일정한 것으로 제한하지 않았다. 이 쉘의 중앙면은 임의의 곡율을 가지며, 쉘의 두께도 임의적으로 변한다. 자오선방향, 두께방향, 원주방향으로의 변위 성분인는 시간반응의 정현성(sinusoidal)과방향으로의 주기성을 지니며,와 z 방향으로는 대수다항 식의 형태로 가정되었다. 이 쉘의 변형률에너지와 운동에너지를 공식화하였으며, 진동수의 최소화를 통해 상위경계치의 진동수를 구하고 다항식의 차수를 증가시켜 엄밀해에 수렴된 진동수를 구할 수 있다. 선형적으로 두께가 변하는 두꺼운 원추형쉘과 구형쉘에 대한 예를 통하여 하위 다섯 개의 진동수에 대해서 유효 숫자 4자리까지의 정확한 수렴성연구가 이루어졌다. 이 해석 방법은 두께가 매우 두꺼운 쉘 뿐만이 아니라 얇은 쉘에도 적용이 가능하다