WELCOME TO PRESENTATION ON

COLUMN(STEEL STRUCTURE)

UTTARA UNIVERSITYDEPARTMENT OF CIVIL & ENVIRONMENTAL

ENGINEERING

WHAT IS COLUMN?Column is a vertical structural member. It transmits the load from ceiling/roof slab and beam, including its self-weight to the foundation. Columns may be subjected to a pure compressive load. Steel columns are the most widely used now-a-days.

Types of ColumnLong Column or SlenderShort ColumnIntermediate Column

Steel ColumnStandard Structural Steel Sections

Build-up Column Sections

ADVANTAGES OF STEEL COLUMN

High Strength : This means that the weight of column that made of steel will be small.

Uniformity: Properties of steel do not change in any portion of Column.

Elasticity : Steel follows Hook’s Law very accurately.

ADVANTAGES OF STEEL COLUMN

Ductility : Steel can withstand extensive deformation without failure under high tensile stresses

Toughness : Steel has both strength and ductility

DISADVANTAGE OF STEEL COLUMN

The use of steel columns is very economical because of their high strength and slenderness of a compressive column is increased, its danger of buckling increases

The strength of structural steel member can be reduced if this member is subjected to cyclic loading.

Under certain conditions steel may lose its ductility , and brittle fracture may occur at places of stress concentration.

DESIGN METHOD

ASD=Allowable Strength Design LRFD=Load Resistance Factored Design.

Load CombinationFor ASD 1D+1L 0.75D+0.75L+0.75W 0.75D+0.75L+0.75EFor LRFD 1.4D 1.2D+1.6L+0.5Lr 1.2D+1.6Lr+(0.5L or 0.8W) 1.2D+1.3W+0.5L + 0.5Lr 1.2D±1E+0.5L 0.9D±(1.3W or 1E)

D=Dead Load, L=Live Load,W=Wind Load, E=Earthquake LoadLr=Roof Live Load

The basic requirements for compression members are covered in Chapter E of the AISC Steel Manual. The basic form of the relationship is

Pu cPn = c(AgFcr)where c is the resistance factor for

compression members (=0.9) and Fcr is the critical buckling stress (inelastic or elastic) and Fe is the elastic buckling stress

The nominal strength Pn of rolled compression members (AISC-E3) is given by

Pn = AgFcrFor inelastic columns or

For elastic columns or

Q =1 for majority of rolled H-shaped section (Standard W, S, and M shapes); Others are covered later

yQFE

rKL 71.4 ye QFF 44.0

yQFE

rKL 71.4

yFQF

cr QFF ey /658.0

ye QFF 44.0

Code Requirements ASD Formula

CcrKL

rKL

rKLE

CcrKL

Ccr

KL

Ccr

KL

CcFy

Fa

rKL

22

2

3

2

149000

23

12

81

83

35

211

Construction process

Detailing

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