Section IV.3

Section IV.3 Single Cell- Multiple Flange Beams: Symmetric and Unsymmetric Cross Sections

This section deals with statically indeterminate box beams with constant-shear-flow webs. For example, a single cell box beam with four stiffeners and four webs. The shear flow analysis in such box beams is basically the same as that discussed in section IV.1 for closed sections.

We cut the cross section at a particular web in order to start the solution at a point with a known shear flow (i.e., q' = 0), and work around the cross section using the general shear flow equation. Then, we replace the cut web and show a constant shear flow qo around the closed cell. This unknown shear flow is the actual value of shear flow in the web that was originally cut. Both the shear center and direct method can be used to solve for the unknown shear flow. The shear flow between stringers can be calculated as in section III.6. Remember that for these problems, the shear flow between two adjacent stringers is constant in both magnitude and direction. The change in direction can only occur at a stringer location.

The example below shows the analysis procedure.

EXAMPLE PROBLEMS

Example 1 Shear flow distribution and shear center location of a single-cell multiple-flanged box beam

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