# Cullen Technical Guide 2024

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FT Timber Frame Wall Tie

FT–50

Tested Values

Compression (kN)

Y m

Tension (kN)

Y m

Nail end (as received) (24mm movement)

1.057 0.612 0.954

0.648 (nail withdrawal)

1.3 (1)

1.15 (3) (buckling of tie – steel failure) 1.15 (3) (buckling of tie – steel failure)

0.690

Masonry end

1.836 (masonry withdrawal)

3 (2)

(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

0.612 0.648 1.836 0.954

1.15

1.1 1.1 1.1 1.1

0.585 0.548 0.673 0.912 0.548

Tension Tension

1.3

3

Compression

1.15

*An instantaneous action (kmod value – 1.1) has be used.

Maximum net surface wind pressure for the FT–50

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–50

4.05

7.4

3.01

5.5

2.41

4.4

2.02

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)

0.548 x 7.4 = 4.05kN/m 2

0.548 x 5.5 = 3.01kN/m 2

0.548 x 4.4 = 2.41kN/m 2

0.548 x 3.7 = 2.02kN/m 2

Peak velocity pressure (kN/m 2 )

2.45

1.82

1.46

1.22

Based on the above values this could be worked backwards Provide a maximum wind load for 3.7 ties/m2 = (2.02/1.1/1.5) = 1.22kN/m2 peak velocity pressure

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