Calculation of Stresses

The distances of a CG of the angle from the corners (obtained from the IS : Handbook) are shown in Figure 5(c).

The stresses at the extreme corner points A, B and C are calculated below as in the case of biaxial bending (Example 7.3).

f_A = -((5746 × 10³ ) × 37)/ 203.2 × 10⁴ +     ((904 × 10³ ) × 72.8)/ 102.1 × 10⁴

= - 107.5 + 64.5 = - 43.0 N/mm² (Compressive)

f_B = -((5746 × 10)³ × 37) 203.2 × 10⁴ -((904 × 10³ ) × 22.2)/ 102.1 × 10⁴

= -107.5 - 19.7 = -127.2 N/mm² (Compressive)

f_C = + ((5746 × 10)³ × 88)/ 203.2 × 10⁴ -     ((904 × 10³ ) × 22.2)/ 102.1 × 10⁴

= 248.8 - 19.7 = + 229.1 N/mm² (Tensile)

The maximum permissible tensile stress (involving wind effects)

= 1.33 × 165 = 219.5 N/mm²

The maximum stress, f_c, is only slightly in excess to this value (< 5%). Hence, the angle may be adopted. Otherwise the further higher section might be chosen.

An compressive stresses being much smaller are within the permissible value.