presenation-moment connection noddy notes
TRANSCRIPT
8/22/2019 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