###### Abstract  
Increasing the lifetime and improving the performance of structures through redesign and optimization are important, especially in marine structures. In general, there are two main groups of marine structures: onshore and offshore structures. Most marine structures are offshore, and these are divided into two categories: floating or sunken. One of the important parameters in the design of sunken structures is the critical load resulting from the buckling of walls, which can cause damage to the structure. In the present paper, three rectangular aluminum and steel compartments of different conditions and sizes were modeled using design analysis methods. Then, different finite element analyses were performed, and the compartments were optimized to reduce the weight of the structure. Finally, the buckling results of three types of rectangular reinforced compartments were calculated and were compared with each other. The results show that the stresses calculated using the analytical method are in good agreement with the results of the finite element analyses. In addition, the weight of the compartment is reduced by utilizing the reinforced conductors in accordance with the design principles and considering the minimum thickness. optimization; buckling; sunken reinforced compartments; marine structure; finite element simulation +
Footnote †: journal: Applied  
Bresler presented a new design criterion for reinforced columns under axial and biaxial bending loads [5]. [PERSON] designed columns subjected to biaxial bending [6]. The Genetic Algorithm (GA) was used to investigate the behavior of reinforced concrete columns under buckling phenomenon [7]. [PERSON] et al. studied an analytical solution for biaxial bending in concrete columns [8]. [PERSON] et al. compared the seismic behavior of frame structures considering specially shaped columns and rectangular columns [9]. [PERSON] et al. studied the axial compression stability of a crisscross section column made of square steel tubes filled with concrete [10]. [PERSON] et al. evaluated the cyclic behavior of rectangular reinforced concrete columns under biaxial loading by utilizing experimental data [11]. [PERSON] studied the elastic buckling of steel columns loaded under axial compression condition [12]. [PERSON] et al. analyzed the elastic buckling of steel columns under axial compression load [13]. [PERSON] et al. presented a modified procedure for buckling calculation of steel columns at elevated temperatures [14]. [PERSON] et al. investigated the design of columns with rectangular and L-shapes subjected to axial and biaxial bending loads [15]. [PERSON] and [PERSON] optimized the design of reinforced concrete with rectangular column shapes subjected to axial compression as well as biaxial bending moments [16]. The effects of different column sections (square and rectangle) with different longitudinal reinforcement rates have also been studied [17]. [PERSON] et al. investigated the impact of two types of flux-cored arc and submerged arc welding and different kinds of heat treatment on the strength of High-Strength Steel (HSS) columns [18]. [PERSON] presented a comparative analysis of rectangular and square columns under axial and biaxial bending loads [19]. The results indicated that applying appropriate heat treatment leads to increased strength of the structure in the range of 3-7%. Moreover, a methodology has been presented to test the HSS columns [20]. [PERSON] and [PERSON] conducted a series of different experiments on rectangular flat plates under edge compression to assess strength [21]. The strength of thin plates under compression conditions has also been reported [22]. [PERSON] et al. investigated the vibration behavior of ring-stiffened polymer composite thick shells used for underwater structures [23]. The tests were done in the air and in water. Free-free boundary conditions have also been considered for modal analysis, which showed that the natural frequency in water was lower than that in air.