Structural bridge’s types: 1. Beam span; 2. Frame, arch, suspension and cable-stayed bridges Materials: 1. Reinforcement concrete; 2. Steel (hot-rolled cross-sections) 3. Steel (cold-formed cross-sections) Base difference of thin walled from thick-walled cross-section is concluded in behavior laws: breach of Bernoulli (plane-sections) hypothesis. Simple example is I-section deformation, when the last is loaded on end by bimoment. Deviation from Bernoulli (plane-sections) hypothesis is more characterized for open then for closed thin walled cross-sections. This is taken into account in non-linear analysis of pedestrian bridge structure. Besides analysis according to 2 rd order theory also non-linear material models for metallic materials is considered. The applied elastic-plastic-zone theory is based on the interaction of any internal forces and moments.