Bolted Joints

Question 1

What type of screw needs a special tool to undo

Answer 1

Tamper-resistant screw head

Question 2

What is minimum proof strength and what symbol does it have?

Answer 2

Sp

strength at which threads will have permanent deformation

Question 3

PERMANENT joint fp value

Answer 3

0.9

Question 4

NON-PERMANENT joint fp value

Answer 4

0.75

Question 5

Typical values for C:

Answer 5

0.15 ~ 0.4

Question 6

km and kb relationship for an ungasketed joint

Answer 6

km ~= 3 kb

Question 7

Two tensile loading failure modes:

Answer 7

1) Joint separation
2) Bolt yielding

Question 8

Total km eqs when the two mats are different

Answer 8

(like resistors in parallel)

1 / km = (l1 / A1 E1) + (l2 / A2 E2)

Question 9

Final force for the bolts

Answer 9

Fb = Fi + CP

Question 10

Final force for the materials

Answer 10

Fm = Fi - (1-C)P

Question 11

For a soft joint, common value for C is

Answer 11

1

Question 12

Safety factor eqs for Joint Separation

Answer 12

ns = Fi / (P0 (1 - C))

Question 13

For a hard joint, common value for C is

Answer 13

0

Question 14

Joints in shear with eccentricity

Vertical force distribution, F1 among the num. of bolts, n

Answer 14

F1 = P / n

Question 15

Shear yield strength and max yield stress relationship

Answer 15

Ssy = 0.6 Sy

Question 16

Shear safety factor eqs

Answer 16

ns = Ssy / τ

Question 17

Joints in shear with eccentricity

Moment force distribution, F2 among the num. of bolts, n

Answer 17

F2 = (P l) / (n r)

where P * l is the moment of the external force