Obliczanie na zmęczenie obiektów mostowych w ujęciu norm PN-EN

Cyclic loads may cause damage in the constructions as a result of fatigue. General rules for determining all effects on bridges are specified in PN-EN 1990 and Appendix A2. Verification if there is no structural damage due to fatigue should be performed in accordance with the scheme of PN-EN, include the scope of the Ultimate Limit Stage (ULS) verifications. For the reason, that fatigue failure does not occur as a result of the load of a fixed maximum value but as a result of repetition of imposing load on an average level of internal forces, the effect of fatigue depends strongly on the properties of construction materials - steel and concrete. Thus, the effect, in the form of fatigue may be quite different in the case of steel bridges, concrete bridges or even a composite steel-concrete bridges. Therefore, the rules for determining the fatigue load are not specified in the overall standard, but are moved to detailed design standards: PN-EN 1992 to PN-EN 1999. Because of the high complexity of the fatigue verification, in the work the general fatigue calculation rules are presented.