This research expresses the non-linear analysis of the impacts of the cross sections and number of stiffeners in improving the buckling and ultra-buckling behavior of plates that have been stiffened with longitude stiffeners under the impact of pressure axial load and prior to final destruction with the parameters free from stress dimensions as imposed to the materials submission stress ( uF y s s ) and deformation of the end part of sample to the initial length of the sample ( int end d d ). The results obtained from the numerical analysis were then compared to the lab results and the accuracy was measured.The numerical analysis of samples was performed by using ABAQUS software. According to the results, it could be stated that as the number of stiffeners increases in general status of dimensionless parameter ( int end d d )decreases in numerical analysis, andsubsequently the dimensionless parameters ( uF y s s ) of the samples increases). In fact, the impact of number of stiffeners could be expressed as increase in the resistance and decrease in deformation in the samples; however, the impact of cross sections of stiffeners in longitudinal deformation of each group of samples could be described as, the model with T-shape stiffener has the least longitudinaldeformation and the model with R-shape stiffeners hasthe highest longitudinal deformation. The final resistance of buckling in models starts from approximately 40 percent of submission resistance and increases up to 70percent of submission resistance in samples. In this research, the lab data performed on steel plates with longitude stiffeners were used with three T, L and R cross sections types to compare and check the accuracy of results of numerical analysis. The numerical analysis results showed a difference of approximately 5 percent with the lab results; the highest difference to be on deformation and initial welding. The method used in analysis could study the results in both elastic and plastic regions.
