Question

Find the number of HSFG bolts of diameter 20mm, grade 88 for connection of member carrying factored tensile load of 200kN when no slip is permitted.

(a) 5

(b) 4

(c) 3

(d) 2

This question was posed to me during an interview for a job.

Query is from Bolted Connections topic in section Bolted Connections of Design of Steel Structures

Answer 1

The correct answer is (b) 4

For explanation I would say: Fo=0.7fubAnb=0.7x800x0.78x(π/4)x20^2x10^-3=137.22 kN

Assume μf=0.5, ne=1, kh=1

Slip resistance of bolt = μf ne kh Fo/1.25 = 0.5x1x1x137.22/1.25 =54.88 kN

Number of bolts required = 200/54.88 = 3.64 = 4(approximately).