WHAT IS COMPRESSION MEMBER IN DESIGN OF STEEL STRUCTURE ? EFFECTIVE LENGTH FOR COLUMN AND DETAILS OF TYPES OF COLUMN
Compression member
1. Compression member is a structural member of a steel
structure which carries compressive load
2. A vertical compression member is called as column whereas
compression member of a roof truss is called as struts.
3. A strut may be inclined or horizontal whereas column is necessarily
vertical.
Axial compression member
Axial compression member is a structural member which
carries compressive load along its axis
Types of compression members
Generally compression member’s types are depends on the
placing of the particular member like explain in below examples.
Selection for columns
Mainly we can design the column with this two types of
arrangements discussed below
1. Angle sections
Angle section placed fact to face (only used in the case of
short column)
2. Double channel
Double channel sections (placed back to back, face to face,
toe to toe.) with or without cover plate are commonly used for column sections.
Effective length for column (Le)
The effective length of column is derived from the actual length
of the member on the basis of its end connections or end restraints (conditions)
The effective length of the column can be taken from the
below give table on the basis of their end conditions
Sr. no.
|
Degree of end
restraint of compression member
(End conditions)
|
Effective length
(Le)
|
symbol
|
1 |
Effectively held in position at. Both the end and restrained (controlled) against rotation at both the ends. |
0.65L |
 |
2 |
Effectively held in position at. Both the end and restrained (controlled) against rotation at one end. |
0.30L |
 |
3 |
Effectively held in position at. Both the end but not restrained (controlled) against rotation at both the ends. |
1.00L |
 |
4 |
Effectively held in position and restrained (controlled) against rotation at one end
And
Not held in position
and restrained (controlled) against rotation at other end.
|
1.20L |
 |
5 |
Effectively held in position and restrained (controlled) against rotation at one end
And
Not held in position
and partially restrained (controlled) against rotation at other end.
|
1.50L |
 |
6 |
Effectively held in position and not restrained (controlled) against rotation at one end
And
Not held in position
and restrained (controlled) against rotation at other end.
|
2.00L |
 |
7 |
Effectively held in position and restrained (controlled) against rotation at one end
And
Not held in position
and not restrained (controlled) against rotation at other end.
|
2.00L |
 |
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