Week 2 Challenge

QUESTION - 1:

To find: Net section area

Given : Plate = 260 x 20mm

Bolt : 20mm dia

1. Plate – Drilled hole:

A_n = (b-nd_h)t

n = 12nos of holes

d_h = 20mm dia.

t = 20mm

b = 260 mm

Solution:

A_n = [260-(12x20)]20

An = 400mm2

1. ii)Plate – Zig Zag bolting:

An = [b- ∑d_h + ∑(p²+4g)]t

P = 110mm; g = 260mm; ∑d_h = 7x20 = 140mm

n = 7nos of holes

Solution:

A_n = [260 – 140 + (110² + 4(260))]20

An = 265200mm2

1. iii)L- Angle:

b = 300mm; P = 150mm; g = 220mm;

n = 6nos of holes; t = 20mm; d_h = 20mm

Solution:

∑d_h = 6x20 = 120mm

An = [b- ∑d_h + ∑(p²+4g)]t

= [300 – 120 + (150² + 4(220))]20

An = 471200mm2

QUESTION - 2:

To find: Section size for given tensile load.

Given : P = 500kN

L = 5m

f_y = 350N/mm²

Solution:

σ = P/A

350 = 500x10³/A

A = 1428.57mm²

Assume angle, 100x100x8mm

A = 15.39cm2

a) Design strength of the member due to yielding:-

Tdg = 0.909 f_y A_g

= 0.909 x 350 x 1539

Tdg = 489.63kN

b) Design strength of member by tearing of net section:-

Tdn = 0.72 f_u A_n

f_u = (500x10³x1.5)/1539

fu = 487.32N/mm2

A_n = (b-nd_h)t

= (200 – 160)8

An = 320mm2

Tdn = 0.72 x 487.32 x 320

Tdn = 112.28kN