Many attempts have been made to evaluate the buckling loads of plates with various support conditions to predict the strength of plate girders. These attemps have been based on the assumption that the deflections of webplates are relatively small compared with the thickness of the webplates. Due to this assumption, many inappropriate results have been obtained, and the current design practice of plate girders is still based on these results. For this reason, many experimental investigations, and theoretical investigations based on the large deflection theory of plates have been performed.
In this paper, a theoretical method of analysis of webplates with large deflections is proposed. A plate girder panel is simulated by an ideal mechanical model consisting of a thin plate and four beams representing the webplate, two vertical stiffeners, respectively. The loading is a general combination of bending moments and shearing stresses. A method of expanding the unknown displacement components into polynomial series is employed with the magnitude of load taken as the expansion parameter. The sets of linearized partial differential equations are then converted into sets of simultaneous linear algebraic equations by means of finite differences and numerically solved by a digital computer.
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