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FT Timber Frame Wall Tie
FT–75
Tested Values
Compression (kN)
Y m
Tension (kN)
Y m
Nail end (as received) (24mm movement)
0.504 0.582 0.786
0.672 (nail withdrawal)
1.3 (1)
1.15 (3) (buckling of tie – steel failure) 1.15 (3) (buckling of tie – steel failure)
0.690
2.265 (masonry withdrawal)
3 (2)
Masonry end
(1) from BS EN1995-1-1 table 2.3 connections (fixing withdrawal of tie) (2) from NA to BS EN1996-1-1 table NA.1 (mortar failure of tie) (3) from NA to BS EN1995-1-1 table NA.3 (steel buckling of tie)
Based on the following criteria the following calculations have been done:
In the following examples a factored windload of 1.65kN/m 2 is suggested
Partial factor for variable action Combined pressure coefficient
1.5 1.1
Peak velocity pressure
= 1.0 kN/m 2 = 1.65 kN/m 2
Applied wind load on gable panel
= 1.5 x 1.1 x 1.0
Failure
Test Result (kN)
Y m
kmod
Result x kmod / Y m (kN)
Compression
0.504 0.672 2.265 0.786
1.15
1.1 1.1 1.1 1.1
0.482 0.568 0.830 0.751 0.482
Tension Tension
1.3
3
Compression
1.15
*An instantaneous action (kmod value – 1.1) has been used.
Maximum net surface wind pressure for the FT–75
Vertical Tie Spacing (mm)
225
300
375
450
Stud Centres (mm)
Product Code
600
600
600
600
Maximum Net Surface Wind Pressure
kN/m 2
ties/m 2
kN/m 2
ties/m 2
kN/m 2
ties/m 2
kN/m 2
ties/m 2
FT–75
3.56
7.4
2.65
5.5
2.12
4.4
1.78
3.7
1000/225 = 4.4444 4.4444x(1000/600) = 7.4 ties/m 2
1000/300 = 3.3333 3.3333x(1000/600) = 5.5 ties/m 2
1000/375 = 2.6666 2.6666x(1000/600) = 4.4 ties/m 2
1000/450 = 2.2222 2.2222x(1000/600) = 3.7ties/m 2
Lowest failure (with Ym & kmod applied)
0.482 x 7.4 = 3.56kN/m 2
0.482 x 5.5 = 2.65kN/m 2
0.482 x 4.4 = 2.12kN/m 2
0.482 x 3.7 = 1.78kN/m 2
Peak velocity pressure (kN/m 2 )
2.157
1.606
1.284
1.078
Based on the above values this could be worked backwards Provide a maximum wind load for 3.7 ties/m2 = (1.78/1.1/1.5) = 1.078kN/m2 peak velocity pressure
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