Experimental and numerical study on stability loss of innovative geometry steel girder

This paper presents the experimental and numerical analysis of an innovative plate girder geometry with variable web thicknesses. An idea proposed in this research is to increase the stability of the girder web by increasing its thickness in the compressed zone. This solution can replace commonly used longitudinal stiffeners which are designed to prevent web local loss of stability. Moreover, such an innovative approach requires only one additional butt weld along the entire element, which is technologically a simpler, cheaper and faster operation (due to the possibility of full automation of production) compared to manual welding of individual stiffeners. The experimental and numerical study shows that application of a web with variable thickness in I-shaped plate girder geometry subjected to four-point bending results in a change in failure mechanism from local to global one. Moreover plate girders with single and double-sided longitudinal stiffeners have been tested numerically. The result of the study clearly shows that values of ultimate load estimated for plate girders with longitudinal stiffeners were smaller than those obtained for innovative ones. It confirms that the proposed solution may prevent web from local stability loss and increase plate girder stability due to bending. This innovative method can be also considered as an effective procedure of strengthening the web in its compressive zone compared to commonly used longitudinal stiffeners.