For the rational and economic design of the structural elements of ships which is built using welding, the ultimate strength analyses of the plates having initial imperfections, such as welding residual stresses and strains, are needful. The welding deformation usually relied on approximative equations or based on expert's experience. But in this paper, for the thermal elasto-plastic analysis of plates, the finite element analysis was performed, based on initial strain method. In formulating the incremental analysis, unbalanced force terns were included. In the plastic domain during the incremental process, the 2nd order terns stress increment and yield stress increment were considered, so that time increment could be controlled for a more stable solution. The ultimate strength analysis program of the plates having initial imperfections was made. The ultimate strength analysis was carried out based on the results of the welding deformations of this paper. In the ultimate strength analysis the Rayleigh-Ritz method based on the minimum potential theory was used.

최근에는 고장력강의 사용증대와 함께 구조부재가 경량화추세에 있으며 이상부식이 발생한 구조부재는 강도가 크게 저하되리라 예상되지만 지금까지 이에 관한 연구가 거의 없는 상태이다. 본 연구에서는 단소성대변형유한요소법을 적용하여 국부이상부식을 가진 판이 면내압축하중을 받을 경우에 압축최종강도에 미치는 부식부영역의 크기. 부식부의 판두께 감소량 및 세장비의 영향에 대하여 연구하였다.