Fatigue induced by breathing on slender webs

J. Construct. Steel Res. Vol. 46. Nos. I-3, pp. 415, papernumber 29, 1998 01998 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0143-974X/98 $19.00 + 0.00 PII: SO143-974X(98)00102-8 ELSEVIER

Fatigue Induced by Breathing on Slender Webs J. Costa and E. Mirambell Escola Tkcnica Superior d’Enginyers de Camins, Canals i Ports, Departament d’Enginyeria de la Construccib, Universitat Politbcnica de Catalunya, Barcelona, Spain

Paper Number 29 Full paper on enclosed CD-ROM

The design of steel webs based on the postcritical resistance permits the webs to be loaded above their critical load of shear buckling, to buckle and to have elastic or plastic out-of-plane deformations. The out-of-plane strains of the web lead inevitably to the appearance of stresses called “secondary bending stresses”, producing an increase in the principal stress. Recent experimental tests have shown that the magnitude of these stresses under repeated loading can result in premature fatigue cracks at the welded web-flange and webstiffener boundaries and lead to girder failure. In this paper the importance of these phenomena is studied by means of a numerical method based on the finite element method taking into account the material and geometrical nonlinearities. A parametric study is carried out using this numerical model. A simplified formulation for fatigue resistant design is proposed and the results obtained are compared to experimental and numerical results. 0 1998 Elseuier Science Ltd. All rights reserved

KEYWORDS Local buckling, finite element method, fatigue, shear buckling, web breathing.

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