U

Outer plies perpendicular to the webs

25hf

0.1i

Particleboard or fibreboard^

30hf

0.2i

t hf is the thickness of the flange being subjected to compression. ^i is the span of the composite section. With random fibre orientation.

t hf is the thickness of the flange being subjected to compression. ^i is the span of the composite section. With random fibre orientation.

7.3.2.2 Plate buckling

For the compression flange, in addition to complying with the shear lag criteria in Table 7.2, in order to prevent plate buckling from occurring, bc>ef must also comply with the maximum effective width criteria for plate buckling, also given in Table 7.2.

Also, unless a full buckling analysis is undertaken, the clear flange width, bf, should not be taken to be greater than twice the effective flange width derived from the plate buckling criteria in Table 7.2.

7.3.2.3 Section properties

The properties of these sections are determined in the same way as in 7.3.1 for thin webbed beams. Equations (7.3)-(7.8) will apply, but in this case the area of the flanges and the webs will be as follows:

• Af: the total flange area, Af = hfjc(bc>ef + bw) + hfjt(bt>ef + bw);

Here the symbols are as shown in Figure 7.5 for an internal I-beam and for an end beam.

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