Design Information - Beam 18 - Carrolls Wholesale Timber

Mechanical Properties

Mechanical properties have been determined in limit state format form with a comprehensive testing and evaluation program carried out by Hyne Timber. The modulus of rigidity is calculated by using G = E/15.

Density is a measured property and is determined as average seasoned density. However properties such as Bearing Strength Perpendicular to Grain, Bearing Strength Parallel to Grain, Shear Strength at Joints Details and Tension Strength Perpendicular to Grain are secondary properties which are depending on the strength group for the material and are determined in accordance with AS1720.1-2010. Further joint group are based on the material used and the groups are defined based on species and density as per AS1720.1-2010.

Property	Beam 18
Stress Grade	GL18
Bending Strength	F_b = 45MPa
Tension Strength	F_t = 25MPa (parallel) F_tp = 0.6MPa (perpendicular)
Shear Strength	F_s = 5.0MPa (in beam) F_sj = 7.3MPa (at joint details)
Compression Strength	F_c = 45MPa
Bearing Strength	F_l = 59MPa (parallel) F_p = 19MPa (perpendicular)
Modulus of Elasticity	E = 18,500MPa
Modulus of Rigidity	G = 1,230MPa
Strength Group	SD3
Joint Group	JD3
Density	750kg / m³

Capacity Factor

Values of capacity factor (F) for calculating the design capacity of (F Rd) of structural members. Note that in this context, ‘area’ should be taken as the plan area.

Structural member in houses for which failure would be UNLIKELY to affect an area greater than 25m²; or SECONDARY member in structures other than houses:

F = 0.95

Structural member in houses for which failure would be LIKELY to affect an area greater than 25m²; or PRIMARY structural member in structures other than houses:

F = 0.85

Primary structural member in structures intended to fulfill an essential service or post disaster function:

F = 0.75

Conductivity K

Where moisture content is below 25%, approximate thermal conductivity k across the grain can be calculated with a linear equation of the form:

k = G_x (B + C_x) + A

Where G_xis specific gravity based on oven dry mass and volume at moisture content x (%) and A, B, and C are constants.

For G_x> 0.3, temperatures around 24ºC and x < 25% MC, the values of the constants are as follows:

A = 0.01864
B = 0.1941
C = 0.004064 (k in W m_-1 K_-1)

G_x= 0.65

Camber

Hyne Timber glue laminated (glulam) beams with a “C” postfix designates a vertical camber radius of 600mm. An “S” postfix designates a straight beam profile.

Alignment tolerance of both straight and cambered beams shall be no more than 1mm per metre of beam length. Cambered beams are generally supplied with a marking stamped on the top edge of the beam. Unless specifically requested (such as for large cantilevers), cambered beams should not be installed with the camber arch facing downwards.

Service Classes

SERVICE CLASS 1

Characterized by a moisture content in the materials corresponding to a temperature of 20ºC and relative humidity of the surrounding air only exceeding 65% for a few weeks per year (Note: The average equilibrium moisture content in most glue laminated timber products will not exceed 12%).

SERVICE CLASS 2

Characterized by a moisture content in the materials corresponding to a temperature of 20ºC and relative humidity of the surrounding air only exceeding 85% for a few weeks per year (Note: The average equilibrium moisture content in most glue laminated timber products will not exceed 20%).

SERVICE CLASS 3

Characterized by climatic conditions leading to higher moisture contents than Service Class 2, or where timber is directly exposed to sun and/or rain (Note: Refer to Hyne Timber Technical Data Sheets for further information).