Week 2:About HSS

Question 1

What does Cf (C subscript f) represent?

Answer 1

Compression force

Question 2

List 6 advantages of hot-formed HSS

Answer 2

1 tighter corner profile for RHS/SHS
2 slightly higher section properties (A,S,I,r)
3 easier weldability in corner regions
4 higher capacity as a compression member;under dynamic loading
5 better notch toughness
6 no need to galvanize

Question 3

List the two methods of manufacturing hot-rolled coils

Answer 3

1 BOF Basic oxygen furnace (uses about 40% recycled steel)

2 EAC Electric-Arc furnace (uses nearly 100% recycled steel)

Question 4

List 2 methods of producing cold-formed HSS

Answer 4

1 Continuous forming method(circular tubes made before other shapes formed out of it
2 Direct forming method (shapes can be formed directly; not used in Canada)

Question 5

What is a possibility when hot-dip galvanising cold-rolled Steel tubes?

Answer 5

Liquid metal embrittlement which causes corner cracking

Question 6

How is corner cracking controlled in cold-rolled HSS?

Answer 6

The standards recommend limits on corner radius such as radius <= 3t (less than or equal to 3t)

Question 7

What are 2 the methods of fire protection for HSS with examples?

Answer 7

1- Active fire protection (use of water within HSS tube)

2-Passive fire protection (intumescent coatings, concrete filling)

Question 8

List 2 conditions under which corrosion not occur in an HSS

Answer 8

1 when it is located inside an enclosed building

2 when HSS is sealed

Question 9

How do you stop water from accumulating in HSS and possible freezing and expanding and bursting the member?

Answer 9

Create drain holes (13mm at least) and galvanize

Question 10

What is the one downside to metalizing?

Answer 10

It’s more expensive than galvanizing

Question 11

Define hardness

Answer 11

The ability of steel to resist indentation

Question 12

Define toughness

Answer 12

The ability of steel to absorb energy or resist impact

Question 13

List the 7 grades of steel discussed in CIV1175

Answer 13

CAN/CSA-G40.20/G40.21
ASTM A500
ASTM A1085
ASTM A1065
ASTM A847
ASTM A53
ASTM A501 imported hot formed steel
API 5L

Question 14

What does ERW stand for?

Answer 14

Electric resistance welding

Question 15

What does SAW stand for?

Answer 15

Submerged arc welding

Question 16

What is the equivalent of ASTM A1085 supplementary requirement s1 in Canadian grade?

Answer 16

CSA G40.21 Class H

Question 17

What is the difference between CSA G40.20/21 Class H and C?

Answer 17

Class C is not hot-finished, Class H is

Question 18

Are ASTM A1058 and CSA G40.20/21 equivalent?

Answer 18

Yes

Question 19

Why is HSS good in torsion (especially CHS)

Answer 19

Effective cross section due to closed shape uniform distribution of material about longitudinal axis

Question 20

Why is HSS good in compression.

Answer 20

Favourably weak radius of gyration

Question 21

List 2 advantages HSS has over wide flange steel sections

Answer 21

1- Cheaper

2-Lighter

Question 22

What causes concern in curved steel HSS wall distortion? Hot bending or cold

Answer 22

Cold

Question 23

Describe galvanising

Answer 23

Immersing steel in molten zinc

Question 24

Describe metalizing

Answer 24

Spraying steel with melted zinc/alumninium

Question 25

Why would one choose galvanising over metalizing?

Answer 25

Because it is cheaper

Question 26

List 2 ways to reduce the chances of cracking of HSS

Answer 26

1- Grinding the inner corners | 2- Specifying corner radius limits less than or equal to 3t

Question 27

What is the Canadian steel grade equivalent to American ASTM A1085?

Answer 27

CSA G40.20/21 Class C

Question 28

Why are HSS’s galvanised

Answer 28

For protection against corrosion