Abstract: Stiffened web girders are widely used in ship hull structures. They are often damaged due to the in-plane loads during ship collision and grounding accidents, certainly affecting the safety of the ship structure. In this paper, the longitudinal stiffened web girder is selected as the research object, the quasi-static impact test and related numerical simulations are conducted to investigate the structural deformation mechanism of web girder subjected to in-plane load. Then, a new deformation model for web girders subjected to in-plane load is proposed in accordance with the features found in the test and simulation analysis. Based on the new model, the analytical formulae for energy dissipation, instantaneous force and mean resistance of web girders are obtained in the light of the plastic analysis. Finally, the new analytical method is verified by the results of model test. It turned out that the proposed analytical method can be a reference to the preliminary structural design and assessment for ship crashworthiness.

Key words: longitudinal stiffened web girder, in-plane load, deformation mechanism, analytical method