EN 338:2016· Europe

D40

Hardwood strength class: bending 40 MPa, E0,mean 13 000 MPa, ρk 550 kg/m³.

All values

Mechanical 10
Design values 14
Physical 2
Moisture and transport not yet
Thermal not yet
Fire 2
Chemical and durability not yet

Mechanical

Elastic

Modulus of elasticity parallel to grain E0,mean

Mean value, for deformation calculations.

Condition	Value	Evidence
	13 000MPa	Single source

Shear modulus Gmean

Mean value, for deformation calculations.

Condition	Value	Evidence
	810MPa	Single source

Modulus of elasticity, 5th percentile E0,05

Parallel to grain. Used for stability (buckling, lateral torsional buckling).

Condition	Value	Evidence
	10 900MPacharacteristic	Single source

Modulus of elasticity perpendicular to grain E90,mean

Mean value, for deformations across the grain.

Condition	Value	Evidence
	870MPa	Single source

Strength

Bending strength fm,k

Characteristic bending strength.

Condition	Value	Evidence
	40MPacharacteristic	Single source

Tension parallel to grain ft,0,k

Characteristic tensile strength along the grain.

Condition	Value	Evidence
	24MPacharacteristic	Single source

Compression parallel to grain fc,0,k

Characteristic compressive strength along the grain.

Condition	Value	Evidence
	27MPacharacteristic	Single source

Shear strength fv,k

Characteristic shear strength.

Condition	Value	Evidence
	4.2MPacharacteristic	Single source

Tension perpendicular to grain ft,90,k

Characteristic tensile strength across the grain; small, so details avoid it.

Condition	Value	Evidence
	0.6MPacharacteristic	Single source

Compression perpendicular to grain fc,90,k

Characteristic compressive strength across the grain: governs bearing at supports.

Condition	Value	Evidence
	5.5MPacharacteristic	Single source

Design values

Modification factor for load duration and moisture kmod

Multiplies characteristic strength: fd = kmod · fk / γM. Wood is weaker under long-lasting loads and when wet.

Condition	Value	Evidence
	0.6	Single source
	0.5	Single source
	0.7	Single source
	0.55	Single source
	0.8	Single source
	0.65	Single source
	0.9	Single source
	0.7	Single source
	1.1	Single source
	0.9	Single source

Deformation factor (creep) kdef

Final deformation = instantaneous × (1 + ψ2 · kdef) for quasi-permanent loads.

Condition	Value	Evidence
	0.6	Single source
	0.8	Single source
	2	Single source

Partial factor for the material γM

Recommended value; each country may set its own in the National Annex (a Nationally Determined Parameter).

Condition	Value	Evidence
	1.3	Single source

Physical

Characteristic density ρk

5th-percentile density.

Condition	Value	Evidence
	550kg/m³characteristic	Single source

Mean density ρmean

Mean density.

Condition	Value	Evidence
	660kg/m³	Single source

Fire

One-dimensional charring rate β0

Charring depth per minute of standard fire exposure on one face.

Condition	Value	Evidence
	0.5mm/min	Single source

Notional charring rate βn

Includes the effect of corner rounding and fissures; used with the reduced cross-section method.

Condition	Value	Evidence
	0.55mm/min	Single source

Sources here are public pages that reproduce EN 338:2016. For design and acceptance, the standard edition named in your specification and the CE marking and Declaration of Performance of the delivered product take precedence. Design factors are recommended values; your National Annex may set others.