Static analysis and stability of the grillage

Steel floor structures for which the grillage is a computational model, are used as carrying systems in building engineering, e.g. in buildings intended for warehouses. The linear and nonlinear static analysis was carried out as well as the verification of grillage sensitivity to the effect of stability loss. Updating of structure geometry description with every step of load increment and updated Lagrange description was applied, and for solution of equilibrium equations the Newton-Raphson method was used with matrix updating with every step of load increment and after each iteration. At dimensioning of the cross-section should be still added conditions connected with internal forces, so-called limit state of load capacity, which requires to fulfill additional conditions, e.g. related to local stability, geometric imperfections, warps and so on, of individual fragments of beam's cross-section, causing increase of rigidity of the grillage and thus carrying away possibility that nonlinear work of the structure occurs under the right conditions of using. Accomplished assessment of the grillage's sensibility to additional compressive loads Fx gives quantitative information relating to their maximum values, so as to fulfil the condition of the limit deflection as well.