Duobalken® and Triobalken® may only be used in service class 1 or 2 according to DIN EN 386: 1996-07 without exposure to extreme climatic change (e.g. air conditioning inside or outside under the roof). Furthermore all applications are permissible for which according to DIN 1052 the use of solid or glulam timber is allowed. Design verification must in all cases be available.
The characteristic values of strength and the calculated values of elasticity and modulus of shear are given from the strength- class of the weakest lamella.
In principle visual as well as mechanical grading is permitted. Presently, however visual grading is customary.
Timber must be in accordance with at least grading- class/strength-class S 10/C24M. Since the individual timber components always have a timber moisture of ≤ 15% the grading- class/ strength-class is denoted with “TS” (for dry sorted).
For Duo-/Triobalken® strength class C24 may deviate from DIN 1052: 2008, table F.5, the modulus of elasticity parallel to the grain to E0,mean = 11.600 N/mm2 applies.
Characteristic values of the strength and stiffness-properties in N/mm2 and the density in kg/m3 for Duobalken® / Triobalken®
| Strength class of the weakest lamella |
C 24 |
C30 |
| Bending strength |
fm,k |
24 |
30 |
| Tensile strength |
ft,0,k |
14 |
18 |
| |
ft,90,k |
0,4 |
| Compressive strength |
fc,0,k |
21 |
23 |
| |
fc,90,k |
2,5 |
2,7 |
| Shear strength |
fv,ka) |
2,0 |
| Modulus of elasticity |
E0,meanc) |
11.600 |
12.000 |
| |
E90,meanc) |
370 |
400 |
| Shear-Modulus |
Gmeanb)c) |
690 |
750 |
| Densitity |
ρk |
350 |
380 |
|
a) The characteristic value of the rolling-shear strength f g,R,k may be applied for all strength classes to 1.0 N/mm2.
b) The rolling-shear modulus can be determined by G g,R,k = 0.10 Gg,mean
|
Other specific values:
-
Material class according to DIN 4102-4: B 2 (normal flammability)
-
Differential shrinkage ratio perpendicular to the grain: 0.24 %/per 1% moisture change
-
Thermal conductivity λ = 0.13 W/(mK)
-
Water vapour resistance value µ: 40
-
The natural durability and corrosion resistance (resistance to aggressive chemical attacks) of Duobalken® / Triobalken® corresponds to the natural durability and corrosion resistance of the respective wood-species, regardless of the adhesive used.
The INFORMATIONSDIENST HOLZ "Konstruktive Vollholzprodukte "(Information Service "Wood Solid and engineered wood products for load-bearing purposes") available for download at www.info.infoholz.de), for example, offers additional information on the properties of various wood species.
