Exercise 6

NTNUNorwegian University of Science and Technology.

Faculty of Marine Technology

Department of Marine Structures.

TMR4205 Buckling and Collapse of StructuresStiffened panels________________________________________________________________________________________Date: March, 2011 Signature: EKim Distributed 7.03.11 Due Date: 14.03.11PROBLEM 1

a) Consider a stiffened panel with thickness t and stiffener spacing b (Figure 1). The panel can be assumed to be long (a > b). It is subjected to axial compression. The plate stiffener can be represented as an unsymmetrical I profile, where the plate flange has an effective width be. Using the effective width relationship for axial compression, derive an expression for the maximum width of the effective plate flange. b) Plot the maximum possible effective width as a function of t for Y =250 MPa and Y=355 MPa. Why is the effective width reduced when the yield stress increases? What is the importance of the plate thickness with respect to total force in the plate flange? Plot also the actual effective width as a function of stiffener spacing for t=10mm and Y =250 MPa.

c) Discuss how the effective width for a plate loaded in compression on its longest edge, a, may be derived. (Hint: Start by discussing the solution for two extreme cases:

i) a/b 1

ii) a/b

Figure 1. Stiffened panel.