## 1 Introduction  
A cylindrically curved plate is an extensively used main member in many industrial fields such as shipbuilding, offshore, automotive, and aerospace industries. In the ship and offshore industries, the curved plate is the most widely used structural member, normally used in applications such as deck plating with a camber, side shell plating at fore and after parts, and bilge circle part. Thus, it is necessary to estimate the buckling strength of a curved plate, because it can be subjected to longitudinal compression under hull girder bending and hydrostatic pressure by seawater conditions. In addition, buckling related issues of curved plates have become more important recently because conventional thick structural steel plates have been replaced with the plates that are relatively thin and made of high tensile steel. In the ship and offshore industries, approval from the classification society is mandatory for shipbuilding. For this purpose, the classification societies have provided design formulae to estimate the buckling strength of curved plates based on the results of commercial finite element analysis. However, there are differences in the design values between the results calculated by the rule given by the classification societies and those obtained from FE analysis. In a previous study, [PERSON] et al. [1] investigated the buckling and ultimate strengths of simply supported curved plates subjected to combined axial compression and lateral pressure by performing a series of elastic and elastoplastic large deflection analyses using commercial finite element program MSC PATRAN/NASTRAN. The numerical buckling analysis results showed that buckling strength and collapse behavior depend on the curvature, initial deflection, slenderness ratio, and aspect ratio. In addition, by comparing the results as per the classification rules and the results of FE analysis, it hasbeen confirmed that the results of the critical buckling strength show significant differences for thinner plates; as a result, the improved design formulae are suggested. In general, this difference occurs because of the absence of an appropriate design procedure for estimating the buckling characteristics of a curved plate, as well as experimental investigations to verify the procedure. For this reason, it is necessary to perform research on the development of an appropriate design procedure as well as conduct experimental investigations to validate the results of FE analysis, and to refine the design procedure. Information on the buckling behavior may be useful when the buckling behavior of curved plates with reduced thicknesses due to corrosion is considered. Therefore, the establishment of an experimental procedure for curved plates and the development of a new design formula are tasks in the ship and offshore industries that must be addressed. In this regard, a few studies that experimentally investigated curved plates have been conducted. [PERSON] reported the results of ultimate strength tests on curved plate girders with circular web openings under transverse compression. It is confirmed that the ultimate load capacity of the girder reduces when the opening and degree of curvature increases in size. In addition, these experimental results are compared with FE analysis using commercial finite element program ABAQUS [2]. [PERSON] et al. performed experiments on six test models of prestressed concrete curved slabs with unbonded tendons. Through validation with the experimental results, a special computer program for estimating the ultimate strength of target structures was developed [3]. [PERSON] et al. observed residual buckling distortion of a mild steel test specimen, which was fabricated by bead-on-plate welding. The experimental result was compared with the result of FE analysis to verify the effectiveness.