The task of this graduation thesis is to model and determine the dimensions of the mathematical model of footbridge using the SAP2000 software package. The assignment of the first part was to make 4 mathematical models of footbridge loaded only with self weight. All four mathematical models differ in static systems. Mathematical models are as follows: steel truss bridge with arched lower chord, reinforced concrete arch bridge with one row of collumns, steel through arch bridge with cables and cable–stayed bridge. After the models were made and results were analyzed, specific criterias were set as well as a point based system. Model with the highest amount of points was additionaly improved and analyzed in the second part. Second part deals with more detailed analysis of the chosen mathematical model. The task was to simulate the behaviour of the bridge in real conditions as best as possible. After all the loads, that can appear when using the bridge, were applied, different load combinations were made. Combination with the biggest impact on the bridge was used in determining the dimensions of the load bearing elements of the bridge. Using modal analysis, basic period of oscillation and natural frequencies were acquired. Natural frequency was compared with the frequency of people walking determined by norm. The possibility of frequency overlap was detected, therefore, measures were proposed to avoid that kind of state.