As per IS 800, what coefficient of friction is assumed for surfaces blasted with shot or grit and hot dip galvanized while calculating the nominal shear capacity of a bolt in a friction type bolted connection, where the capacity is governed by slip?

Question

Question

This question was previously asked in

BHEL Supervisor Trainee Civil 21 Jan 2024 Official Paper

Answer 1

Explanation:

Table 20: Typical Average Values for Coefficient of Friction (μₜ)

(Clause 10.4.3)

Sl No.	Treatment of Surface	Coefficient of Friction, μₜ
i	Surfaces not treated	0.20
ii	Surfaces blasted with shot or grit with any loose rust removed, no pitting	0.50
iii	Surfaces blasted with shot or grit and hot-dip galvanized	0.10
iv	Surfaces blasted with shot or grit and spray-metallized with zinc (thickness 50–70 μm)	0.25
v	Surfaces blasted with shot or grit and painted with ethylzinc silicate coat (thickness 30–60 μm)	0.30
vi	Sand blasted surface, after light rusting	0.52
vii	Surfaces blasted with shot or grit and painted with ethylzinc silicate coat (thickness 60–80 μm)	0.30
viii	Surfaces blasted with shot or grit and painted with alcalizinc silicate coat (thickness 60–80 μm)	0.30
ix	Surfaces blasted with shot or grit and spray metallized with aluminium (thickness > 50 μm)	0.50
x	Clean mill scale	0.33
xi	Sand blasted surface	0.48
xii	Red lead painted surface	0.10