Question

A universal beam section 457 x 191 x 67 is subjected to an imposed uniform loading on a simply supported unrestrained 6 m span beam. The beam is laterally restrained at the support only. Use steel grade S355. Determine the allowable imposed uniform loading.

Answer 1

Step 1:

Data provided are

Beam section = UB 457 x 191 x 67

Steel Grade = S355

Yield strength = 355 Mpa

Step 2:

Section properties from BS 4

Designation Dimensions Static Parameters Moment of Inertia Elastic Section Modulus Depth Width Web Thickness -h -W- -S- Sectional Area Weight Ix ly -Wx - Wy: (mm) (mm) (mm) (cm2) (kg/m) (cm) (cm) (cm) (cm) fin) 453.4 189.9 8.5 85.5 67.1 29380 1452 1296 152.9 UB 457 x 191 x 67

Step 3 : Bending Capacity Calculation

Assuming the shear load to be low (<60% of Shear Capacity) and the section is compact,

Moment Capacity about Major Axis,

Сх py Six

Py = Design strength = 355 N/mm2

Sx = Section Modulus for the Beam section = (Ix/Y)

= (29380*2) / 453.4

= 121 mm3

Therefore, = 121 * 255

Сх py Six

= 42.96 kNmm

Step 4:

Calculating the allowable uniform load (w),

  

w12 Mcx = 42.96 kNmm 00

Therefore on calculating, the maximum allowable Unifrom Load is 9.5 N/mm