Drift wire chambers are detectors used to track charged particle with a space resolution up 100m. Large arrays of tensioned wire in a gas volume provide an electrical filed capable to detect the ionization caused by the passage of particles. The mechanical support structures must guarantee the wires positioning and tensioning and the gas confinement in the tracking volume. The tensioned wires produce on the mechanical structures stress and deflection that must be study in detail with high level of reliability on the results, because no prototypes are affordable. Mechanical requirements are sometime very stringent and required the use of composite material and complex assembly procedures. The purposes of FEA models are to guarantee the achievement of the requirements. Examples of different studies and approaches are outline on the basis of experiences made.