Fatigue failure mechanisms of thin-walled hybrid plate girders

Steel plate girders of bridges and industrial structures are usually subjected to dynamic fatigue loading. Their thin-slender webs under dynamic fatigue loading are laterally buckling and vibrating. The consequence of that can be arising and successive development of fatigue cracks along the welded connections of the thin webs with flanges and stiffeners. Therefore, the fatigue strength and life/time of thin-walled plate girders depend beside of usual material-technological and structural influences also on stability aspects. Basic knowledge about fatigue failure mechanisms of thin-walled hybrid plate girders is presented with the regard for their local stability, obtained and by theoretical an experimental analyses. The outcome of obtained results is that the fatigue consequences of thin webs vibration can be effectively reduced by appropriate reduction of their slenderness. Therefore, the empirical formula for the limitation of web slenderness has been proposed and recommended for plate girders subjected to dynamic fatigue loading.