Influence of patch load length on strengthening effect in steel plate girders. (August 2022) - Ceranic, A.
Abstract: The present paper aims to numerically investigate the influence of patch load length related to various geometric parameters on the patch loading resistance of steel plate girders. Geometric parameters such as the web thickness, web panel width, and flange thickness are varied in combination with flat longitudinal stiffeners with varying rigidity in determining ultimate strength for various patch load lengths. Of primary interest in this paper is the strengthening effect, defined as the ratio between the ultimate strength of longitudinally stiffened and unstiffened steel plate girders. The strengthening effect for different patch load lengths depends on the rigidity of the longitudinal stiffener, web slenderness, web panel aspect ratio, and stiffness of the loaded flange. Small strengthening effects are obtained for relatively small patch load lengths and all parameters considered. A noticeable strengthening effect is observed for longer patch load lengths. The European design standard EN 1993-1-5 returns uniform strengthening effects independent of patch load length. This is a direct consequence of the definition of the effective loaded length in EN 1993-1-5. The effective loaded length is the same for longitudinally unstiffened and stiffened steel plate girders, and thus, there is no enhancing contribution due to longitudinal stiffening. Therefore, new calculation formulae for predicting the collapse load of longitudinally unstiffened and stiffened steel plate girders subjected to patch loading are defined. The design expressions are determined based on the present numerical results and verified by comparison with experimental and computational results available in the literature. Highlights: Strengthening effect in longitudinally stiffened plate girders subjected to patch loading varies with patch load lengths. Small strengthening effects are obtained for relatively small patch load lengths. Noticeable increases in strengthening effect are obtained for longer patch load lengths. Strengthening effect increases even for flexural rigidities of the longitudinal stiffener higher than the limit value. In-plane bending rigidity of the longitudinal stiffener plays an important role in the strengthening effect.