In linear analysis it is assumed that the material reaction and the construction’s reaction is in proportion to the load which affects it. This assumption results in lower deformations than in reality and the material- and construction properties remains constant. While the linear analysis approximations bring out the opportunity to calculate by hand and less usage of less processor power in a computer, the method has numerical incorrections compared to non-linear analysis. As the non-linear analysis iterates and the linear method is using the principle of super position, the numerical differences become greater with more complex loading and geometric features of the construction.The non-linear analysis considers non-linear behaviors as the change of material properties, changing supportive reactions under load and geometric change of the structure under load. In addition to these, non-linear analysis takes plastic deformations and cracking of the concrete in consideration.This study is based on the simulations of two different geometric structures. One simply supported steel reinforced concrete slab and a rectangular steel reinforced concrete tunnel structure.The result of this study indicates that linear analysis underestimates the forces within the structure compared with non-linear analysis. The non-linear analysis shows increased deformations of all kinds compared to linear analysis. Even though the process of using non-linear analysis might be more time consuming than using linear analysis, the representation of the numerical values could be more realistic.The results also show that the longitudinal moment of both structures was significantly larger while using non-linear analysis than with a linear analysis. This study is examining the numerical difference of the two analysis methods based on the complexity of the geometric structure and loading. as well as the support reactions and the loading properties.