Rolled Steel Sections

 

Rolled Steel Sections

 

    Structural steel sections are hot rolled into different shapes and sizes to form the different sections. Cross section and size are governed by functional requirements, dimensional and weight capacity of rolling mills, arrangement of material for optimum structural efficiency. In a rolling mill molten steel from furnace is poured into continuous casting system where steel solidifies but it is not allowed to cool completely. Then hot steel passes through series of rollers. Such series of rollers squeezes steel into desired cross sectional shape. If the load to be resisted is small single rolled steel sections are used. If the single section is insufficient, single sections are combined or built up with angles/ channels/ I sections with or without cover plates and /or laced, providing sufficient resistance to heavy loads.

Most commonly used hot rolled steel shapes are as follows:

1. Rolled Steel I -Sections

2. Rolled Steel Channel Sections

3. Rolled Steel Angle Sections

4. Rolled Steel T-Sections

5. Rolled Steel tube sections

6. Rolled Steel Plates

7. Rolled Steel Sheets

8. Rolled Steel Flats

9. Rolled Steel Strips

10. Rolled Steel Bars

Figure: Rolled Steel Shapes

1. Rolled Steel I -Sections

a) Indian Standard Junior Beams (ISJB)

b) Indian Standard Light Beams (ISLB)

c) Indian Standard Medium Weight Beams (ISMB)

d) Indian Standard Wide Flange Beams (ISWB)

e) Indian Standard Column Sections (SC) or (ISSC)

f) Indian Standard Heavy Weight Beams (ISHB)

 

All above sections are designated with the depth of the respective section in mm. for example, ISMB 400 where, 400 indicates the depth in mm.

I sections are used as a beam and column in steel structure.

2. Rolled Steel Channel Sections

a) Indian Standard Junior Channel (ISJC)

b) Indian Standard Light Channel (ISLC)

c) Indian Standard Medium Weight Channel (ISMC)

d) Indian Standard Medium Weight Channel With Parallel Flange (MCP)

All above sections are designated with the depth of the respective section in mm. for example, ISJC 100 where, 100 indicates the depth in mm.

Channel sections are used for column and purlins in steel structure.

3. Rolled Steel Angle Sections

a) Indian Standard Equal Angles

b) Indian Standard Unequal Angles

Angle sections are designated by abbreviation ISA along with the lengths of both legs and their thickness. For example, ISA 50 X 50 X 6 mm means an equal angle section of 6 mm thickness and with both legs 50 mm long or ISA 40 X 25 X 6 means an unequal angle section with leg 40 mm, 25 mm in length and thickness of legs 6 mm 

Angle sections are used as tension and compression members as well as purlins in steel structures.

 

4. Rolled Steel T-Sections

a) Indian Standard Normal Tee Bars (ISNT)

b) Indian Standard Wide Flange Tee Bars (ISHT)

c) Indian Standard Long Legged Tee Bars (ISST)

d) Indian Standard Light Tee Bars (ISLT)

e) Indian Standard Junior Tee Bars (ISJT)

f) Indian Standard Deep Legged Tee Bars (ISDT)

g) Indian Standard Slit Medium Weight Tee Bars (ISMT)

h) Indian Standard Slit Tee Bars From I Sections (ISHT)

All above sections are designated with the depth of the respective section in mm. for example, ISLT 75 where, 75 indicates the depth in mm.

T sections are generally used for various steel structures, like water tanks etc.

 

5. Rolled Steel tube sections:

Steel tubes are designated by their outside diameter and self weight.

 

6. Rolled Steel Plates:

Steel plates are designated by length, width and thickness of section for example; ISPL 2500 X 1500 X 6 means the plate is 2500 mm long, 1500 mm wide and 6 mm thick.

 

7. Rolled Steel Sheets:

Steel sheets are designated by length, width and thickness of section for example; ISSH 1800 X 600 X 4 means the sheet is 1800 mm long, 600 mm wide and 4 mm thick.

 

8. Rolled Steel Flats:

Steel flats are designated by width and thickness of section for example, 30 ISF 10 means the flat is 30 mm wide and 10 mm thick.

 

9. Rolled Steel Strips:

Steel strips are designated by width and thickness of section for example; ISST 100 X 5  means the strip is 100 mm wide and 5 mm thick.

 

10. Rolled Steel Bars:

Rolled steel bars may be circular or square and are designated by diameter or side  for example, ISSQ 20 mm means a square bar of 20 mm side and ISRO 20 mm means a round bar of 20 mm diameter.

 

Choice of Section:

Among all above hot rolled steel section, which section should be used that choice depends upon:

1.   Cross sectional area of section

2.   Section modulus

3.   Radius of gyration

4.   Ease with which sections can be connected

5.   Availability of the section in the market.