# Cullen Technical Guide 2024

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HMT High Movement Timber Frame Wall Tie

Product code

Minimum cavity (mm)

Maximum cavity (mm)

HMT–50

45

65

HMT–50

Tested Values

Compression (kN)

Y m

Tension (kN)

Y m

1.705

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

0.895 (nail withdrawal)

1.3 (1)

Masonry end

2.376

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

2.176 (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

1.5

Combined pressure coefficient

1.1

Peak velocity pressure

= 1.0 kN/m 2

Applied wind load on gable panel

= 1.5 x 1.1 x 1.0

= 1.65 kN/m 2

Failure

Test Result (kN)

Y m

kmod

Result x kmod / Y m (kN)

Compression

1.705

1.15

1.1

1.63

Tension

0.895

1.3

1.1

0.757

Tension

2.176

3

1.1

0.797

Compression

2.376

1.15

1.1

2.272 0.757

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

Maximum net surface wind pressure for the HMT–50

Product Code

Vertical Tie Spacing (mm)

225

300

375

450

Stud Centres (mm)

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

HMT–50

5.6

7.4

4.16

5.5

3.33

4.4

2.8

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)

0.757 x 7.4 = 5.6kN/m 2

0.757 x 5.5 = 4.16kN/m 2

0.757 x 4.4 = 3.33kN/m 2

0.757 x 3.7 = 2.8kN/m 2

Peak velocity pressure (kN/m 2 )

3.39

2.52

2.01

1.69

Based on the above values this could be worked backwards Provide a maximum wind load for 3.7 ties/m 2 = (2.8/1.1/1.5) = 1.69kN/m 2 peak velocity pressure

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