Strength of Materials

5.2 SECTION MODULUS

From Equation (5.6), let two terms be considered

 

 

It is known that the stress in a fibre is proportional to its distance from the neutral axis. If y_max is the distance of the extreme fibre from neutral axis then

 

 

Here, Z represents Section modulus or Modulus of section, i.e., Z = I / y_max

Thus, moment of resistance of a section is

 

M = f z = p z

 

where f or p denotes the maximum stress, tensile or compressive in nature.

5.2.1 Section Modulus of a Rectangular Section

For symmetrical section, the neutral axis and ...