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## Homework Statement

The cross-section of an idealised I section beam has overall dimensions 12mm x 240mm deep. If the web and Flange are both 25mm Thick, determine the second moment of area of the section.

If the maximum bending stress is limited to 100MN/m2, determine the maximum bending moment the beam can withstand

## Homework Equations

∂ = Stress Applied

Y = Distance form Neutral Axis

M = Applied moment

I = Second moment of area

E = Youngs modulus

R = Radius (measured to neutral axis)

(∂/y) = (M/I) = (E/R)

I = b . (d^3)

----------

12

Y = depth/2

## The Attempt at a Solution

I = b . (d^3)

----------

12

b= 125-25 = 95

d= 240-50 = 190

I = [0.095 . (0.19^3)] / 12 = 5.4x10^-5

(∂/y) = (M/I)

100x10^6 = M

____________ _____________

{(.24/2)=0.12} {5.43x10^-5}

100x10^6

---------- x 5.43x10^-5 = M

0.12

M= 45000nm

45KNM

Is this correct.

Mike

Also i've just tryed the next (and last) one

Which i have no clue about.

A steel bar of rectangular cross-section is bent into a circular arc of 15m. The with of the cross-section is twice its depth.

If the maximum stress due to bending is 60MN/m2, determine the dimensions of the section and the magnitude of the applied moment.

Take young's modulus as 200GN/m2

Dont even no where to start on that one

Mike

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