Fatigue life of girders with undulating webs

Steel girders with sinusoidally predeformed webs, commonly used in Central Europe and elsewhere, are described. A review of their static and fatigue resistance, based on tests and theoretical analyses performed at CTU in Prague, is presented. First, results of extensive static tests with local patch loading are given. The tests were statistically evaluated in accordance with Annex Z of Eurocode 3, to determine characteristic and design resistance values. The results were verified using geometrically and materially non-linear finite element analyses accounting for imperfections, and supplemented with parametrical studies. The main part of the paper reports on a vast number of tests dealing with the fatigue of undulating webs under cyclic shear and cyclic steady local patch loading. The results are summarised and statistically evaluated into fatigue curves in compliance with Eurocode 3. Finally, tests simulating moving local crane loads are described, for which the cyclic and moving strain patterns in the undulating web were achieved through a special testing rig. Evaluation of these tests and theoretical analysis of local yielding were performed using ANSYS software. Finally, some recommendations are presented for the practical fatigue design of girders with undulating webs.