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Chapter 3Section 2: Columns in Simple

Construction

Columns in Simple Construction Connections are assumed not to develop significant

moments adversely affecting either the members or

the structure as a whole.

The beams may be designed as simply supported.

The columns are designed to carry axial loads as well

as nominal moments from the reaction shear of the

beam, applied at the appropriate eccentricity.

Columns must be fully continuous.

It is assumed that sidesway due to horizontal loading

is prevented by inserting bracing or by utilising shear

walls, lift or staircase closures, acting together with

shear resistance of the floor slab.

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Joints in Simple

Construction

(a) Web Cleats (b) End Plate (c) Fin Plates

100 mm

Simple Construction

Lift Shaft

or stair well

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Simple Braced Frame

Simple Construction

No need to consider pattern loading

Assume all beams at any one level to

be fully loaded

Must consider eccentricity of loading

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No need to consider pattern loading

as shown below

Buckling Capacity

1++yy

y

bs

x

c

c

Zp

M

M

M

P

F

Based on min. (Pcx or Pcy) LT= 0.5L/ry

mLT= 1.0 my = 1.0

Local capacity check is not required

Nominal moments

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Nominal moments

Moment = R x (D/2 + 100mm)

R

100mm

D

t/2

Moment = R x (t/2 + 100mm)

R

100mm

t

D/2

D is the depth of the column t is the thickness of the web

R1

R3

R2

Mx=R2(D/2+100)

My=R1(t/2+100)

R3(t/2+100)

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Column Moments

The applied moment is divided between the

column lengths above and below in

proportion to the stiffness (I/L)

If the stiffness ratio 1.5, the moment may be

divided equally

m=1

The moments have no effects at levels above

and below

Upper column stiffness = I/4

Lower column stif fness = 2I/5

Stiffness ratio =

Example4m

5m

A

2I

I

A M

M

M

u

l

beam

beam

beam 5.16.14/I

5/I2>=

M385.0M

5/I24/I

4/IMu =

+

=

M615.0M5/I24/I

5/I2M l =

+=

*Note: If column stiffness ratio is less than 1.5, then

Ml = Mu = 0.5M

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Buckling Resistance

Where LTB does not need

to be considered Mbs = Mc

In other cases Mbs is

calculated according to

clause 4.3.6.4 using

LT = 0.5 L / ry

1++yy

y

bs

x

c

c

Zp

M

M

M

P

F

Design Procedure

Calculate beam reactions

Calculate moment due to eccentricity

Divide moment between column lengths

Check1++

yy

y

bs

x

c

c

Zp

M

M

M

P

F

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Braced Core to provide lateral stability

UE SQUARE18 Storey office buildi

Steel weight = 1800 to

Castellated beams

Composite slab

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CUPPAGE CENTRE(STARHUB CENTRE)

Completed in 1998

Rebuilt 10-Storey

building

Steel weight = 3000 tons

Composite beam

Encased composite

column Composite slab

Simple construction

Core wall with addition

steel braces for lateral

stability

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Cuppage Centre

Simple connection

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Floor

Diaphragm

Rigid Floor Diaphragm

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EXAMPLE