## 1 Introduction  
Thin steel plate elements are the main structural components of decks and platforms on ships, webs and flanges of plate and box girder bridges, platforms of offshore structures, and architecture structure [1]. Openings are frequently introduced in plates for the purpose of inspection, maintenance, service, etc. [2]. In such cases, the presence of openings redistributes the membrane stresses in the plates and reduces their buckling and compression capacity significantly [3; 4; 5]. The reduced buckling strength of the perforated plate may be insufficient to meet the requirements of normal structural serviceability and safety. In this situation, it is necessary and important to develop a method to improve the buckling and ultimate strength of perforated steel plates.  
Fiber-reinforced polymer (FRP) has large strength to weight ratios, excellent resistance to corrosion and environmental degradation. It is also very flexible to be formed into any desired shape and easy to be handled during construction. Therefore, FRP has been widely used in strengthening steel structures. In recent years, there have been a number of studies on strengthening steel structures, particularly compressed thin-walled structures. [PERSON] and [PERSON] [6; 7; 8; 9] tested hollow structural steel (HSS) specimens strengthened with carbon fiber-reinforced polymers (CFRP) to study the influence on local and global buckling behavior and column strength. The test indicated that the transverse CFRP layers can help restrain outward directed local buckling of two opposite sides for short columns. [PERSON] [10] employed the strengthening technique of externally bonding FRP sheets to selected sides of steel T-sections in order to improve global and local buckling behavior, and the results show that FRP material provides \"bracing\" against the local buckling. [PERSON] and [PERSON] [PERSON] and [PERSON] (2011) tested ten short cold-formed steel circular hollow section (CHS) columns with externally bonded hoop and longitudinal CFRP, the results show that the reinforcing hoop fibers provide better restraining force to postpone the steel skin buckling when the local slenderness ratio is higher, it also shows that the use of a combination of hoop and longitudinal CFRP in a slender tube can promote the attainment of the yield capacity of the bare tube. [PERSON] (1984); [PERSON] (1984); [PERSON] (1984) tests a CFRP wrapped square hollow sections (SHS) columns with width-to-thickness ratio varying from 12.5 to 120. The experimental results show that the axial capacity of the wrapped SHS is up to twice of that without wrapping the CFRP, due to the restraining on the development of elastic buckling deflections from the wrapping CFRP. The critical stress is up to four times of that of the steel section due to this restraining effect. Moreover, a design method is developed whereby the theoretical elastic critical stress of the composite steel-CFRP sections developed by [PERSON] and [PERSON] [PERSON] and [PERSON] (2015) is used to determine the buckling load and the ultimate load.  
The previous description shows that openings are frequently introduced in plates and the application of FRP is an ideal technique for postponing the local buckling and increasing the ultimate capacity of the steel structure. However, the researches on pasting FRP sheets for improving the degraded buckling of perforated plates are not investigated in the published literatures. Therefore, the objective of the present paper is to investigate the material's geometrical and mechanical properties, boundary conditions, a plate aspect ratio, hole sizes, and hole position on elastic buckling of perforated plates strengthened with FRP under uniaxial compression. And a calculation method of buckling stress is proposed and modified based on the theory of composite plate and the numerical results.