presenation-moment connection noddy notes

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MOMENT CONNECTIONS(NODDY NOTES)

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MOMENT CONNECTION

FAILURE POINTS

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LOAD CASES

When the loads are issued, from a client they are generally in the form of a Moment

(kNm), a Vertical Shear (kN) and a Axial Load (kN). These issued loads don’t take

into account any reversal conditions, so the connection needs to be looked at for acouple of different Load cases. These basic cases are shown below.

Moment Shear Axial

Load Case 1 + + +

Load Case 2 + + -

Load Case 3 - + +

Load Case 4 - + -

It can be sometimes a good idea to ask the client for a reduction on the reversal

loads as these will be less in reversal for a majority of the time. This can keep the

size of the connection and the need for extra stiffening to be down to a minimum.

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FLANGE THICKNESS  BOLT TENSION 

10 23

12 33

14 45

16 59

18 74

20 92

22 111

24 132

INITIAL SIZING

The table shows the typical bolt tensions

that can be achieved with the flange

thicknesses shown.

To initially size the connection the lever arm from the bottom of the haunch to the

centre of the top two rows of bolts.

To do this the moment has to be divided

by 4 x the relevant bolt tension in the table

above.

Le = M / (4x BOLT TENSION)

Now the initial size is known the

connection can now be sized properly

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END PLATE DESIGN

To design the end plate the actualbolt tension needs to be found.

To do this the Zxx of the bolt needs

to be found.

Zxx = 2 x ( X1² + X2² + X3² + X4² + X5² )

X5

MOMENT TENSION (TM) = MOMENT / Zxx

In addition there is the tension from the axial force.

 Axial force / N° of Bolts = T A

BOLT TENSION (TT) = TM + T A

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END PLATE DESIGN CONT

To check the end plate the bolt tension is used. The

lever arm from the edge of the web to the centre of 

the bolt is treated as a cantilever.

From the centre of the bolt a 30° dispersal goes

back to the web, the distance between this

dispersal is deemed “B”. The dispersal lines of 

bolts can’t cross, so much of the time the dispersalis half the vertical centres between the bolts as

shown.Double Curvature Bending

Minimum Plate t = √( TT x Le x 6000 / 2 / py / B )

Note: - Horizontal c/c should be no more than 55% of 

the plate width to achieve double curvature bending.

Double Curvature Bending

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COLUMN FLANGE DESIGN

The column flange must be checked in the same way as the end plate.

Minimum Flange t = √( TT x m x 6000 / 2 / py / B )

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COLUMN DESIGNCompression Load

Compression Load = 2 x Tm x ( X1 + X2 + X3 + X4 + X5 ) / X5

Web Bearing Web BucklingWeb Shear 

 Additional Compression Load = Axial Load / 2 

Pv = 0.6 x py x ( t x D ) 

Where

py = Design Strength of Column

t = Column web thickness

D = Depth of the Column

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COLUMN STIFFNER DESIGN

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WELD DESIGN

Main Welds to Consider 

Flange Weld

Web Weld 

Flange Weld

The Flange weld should have the capacity for the compression load. The weld to

the top and bottom of the flange should be taken into account.

Web Weld

The Web Weld should have the capacity to take the load on the top bolt as a

minimum (Axial + Shear).

Minimum Weld Sizes 

Tb = Flange Thickness

tb = Web Thickness 

The loads in the bolt should be taken over the

dispersal distance used in the end plate design. 

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BOLT DESIGN 

Bolt Capacity should be able to take the Axial Load ( TT ) and the Shear Load per 

Bolt. 

The bolts should have the capacity to take both loads combined. 

Fs = Shear Load per Bolt

Ps = Shear Capacity of Bolt

Ft = Tension Load per Bolt (TT)

PNOM = Nominal Tension Capacity of Bolt 

Bolt Bearing 

kbs = 1.0

d = Bolt Ø

t = Thickness of Plate / Flange

pbs = Bearing Strength (S275 = 460N/mm²)

e = Edge Distance

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MISC DESIGN 

Flange Compression

The compression capacity of the flange should be in excess of the compression

load used in the checking of the column.

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MISC DESIGN