structural timber tests
TRANSCRIPT
Structural engineering 1
Assignment: Timber tests
November 2011
Burak ErkanCristian GarabetianLeevi ValkoniemiStefan ManeaYohannes Molla
Assignment: Timber tests
Assignment A: Elastic modulus and resistance of a timber beam under bending
We chose to calculate the elastic modulus at 50% of the ultimate load. In our case that is 1.2512 kN and the deflection 10.534 mm.Thus we found that E = 7361 N/mm^2, which is equal to 7.361 Gigapascals.
Elastic modulus and resistance of a timber beam under bending.Timber strength class - C24.
Assignment: Timber tests
Assignment A: Elastic modulus and resistance of a timber beam under bending
0 5 10 15 20 250
0.5
1
1.5
2
2.5
3Load vs Displacement Beam Bending
Displacement (mm)
Loa
d (
kN
)
Assignment: Timber tests
Assignment A: Elastic modulus and resistance of a timber beam under bending
Comparing the values to table values, we found that our C24 in practice seemed to be C14. (E0,mean = 7Gpa ; fmk=14 Mpa)
What may cause the differences in test and table values?Density changesDefects vary (eg. Knotty timber)Moisture content and temperature changes
- Defects in Strength and stiffness- Swelling
Duration of loading varies
Assignment: Timber tests
Assignment B: Nails strength connection
The specimen was hammered with 6 nails on both sidesof the connection. The distances from the edges and from the other nails were placed according to the regulations.
Assignment: Timber tests
Assignment B: Nails strength connection
Assignment: Timber tests
Assignment B: Nails strength connection
THE PRESENTED SPECIMEN HAS ALREADY LOST THE CAPACITY OF THE CONNECTION.
Assignment: Timber tests
Assignment B: Nails strength connection
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.000.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
Load vs Displacement
Deflection (mm)
Load (
kN
)
Assignment: Timber tests
Assignment C: Compression perpendicular to grain
The experiment consists in determinate a value of compression perpendicular to grain for timber trusses.
type of wood tested was C24.
The tested specimen had the dimensions of: b (breadth) = 50mm; h (height) = 173mm, L (length) = 26,2mm.
Assignment: Timber tests
Assignment C: Compression perpendicular to grain
After the test, maximum load acting on the specimen was 60 kN, with a displacement of 22mm indicated by the tester. The displacement starts after the load was bigger than 1,3kN.A normal straightness for perpendicular compression in case of C24 timber truss should be fc,90,k=2,5 MPa (2,5 N/mm2).
After the results from tester and personal calculation, the straightness was around 10 N/mm2 much bigger because the specimen was still under bigger load to provide enough displacement in order to by noticed.
-5 0 5 10 15 20 250
10
20
30
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60
70
Load vs Displacement Bearing Test
Displacement (mm)
Loa
d (
mm
)
Thank you for your time and your attention-Group 4-