Comparison of Buckling Check Formulas and Optimal Design

J. Ocean Eng. Technol. 2009;23(5):71-78.

Jang Beom-Seon,Cho Ho-Young

Samsung Heavy Industries Co. Ltd.,Samsung Heavy Industries Co. Ltd.

보강판의 좌굴 평가식에 따른 좌굴 강도 및 최적설계의 비교

장범선,조호영

삼성중공업(주) 해양기본설계팀 서울해양설계,삼성중공업(주) 해양기본설계팀 서울해양설계

Keywords: Stiffened plate, Buckling strength, Ultimate strength, Interaction curve

핵심용어: 보강판, 좌굴 강도, 극한강도, 상관관계 곡선

Abstract

In ship design or offshore structure design, the evaluation of buckling strength (or ultimate strength) is critical to the determination of scantling of stiffened plates. For this reason, it is useful to study the effect of applying different formula or the relationship between stiffened plate with buckling utilization factor (UF). It can facilitate a designer to decide how much the scantling should be reinforced or how much can be reduced for an optimal design. This paper conducts a comparative study for three buckling check methods; DNV-Ship-Rule, DNV-RP-C201, DNV-PULS. The capacity curves and 2D contour plot for utilization factors versus bi-axial in-plane stresses are compared. The contour plots of DNV-Ship-Rule and DNV-PULS show smoothly increasing trends of UF as the applied in-plane stresses increase, however that of DNV-RP-C201 shows rapidly increasing trend as the applied stresses go beyond transverse buckling stress. A sensitivity analysis is performed to investigate the influence level of each parameter of a stiffened plate on UF. Resulting from the analysis, plate thickness is identified to be the most affective parameter to UF regardless of the buckling check methods. Based on the addressed study, optimal designs for bottom plate of 165 K tanker corresponding to three formulas are compared with each other. DNV-PULS yields 1 mm and 2 mm less thickness than DNV-Ship-Rule and DNV-RP-C201, respectively.