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Now from the simple bending theory the moment required to produce the yield stress at the edge of the section (in this case the lower edge), i.e. the maximum elastic moment, is ol 6.56 x 10~6 ,

Me =-= erv x -- = 0.065 x 10~3crv ymax 100.5 x 10"3 y

When the section becomes fully plastic the N.A. is positioned such that area below N.A. = half total area i.e. if the plastic N.A. is a distance yp above the base, then yp x 12 = ±(1200+ 1656) y p — 119 mm

The fully plastic moment is then obtained by considering the moments of forces on convenient rectangular parts of the section, each being subjected to a uniform stress ay, i.e.

10"

= oy (30 000 + 2166 + 84 966) 10" = 0.117 x 10"3ctv shape factor =

0 0

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