Apparatus
1. Universal testing machine
2. Pit gauge with magnetic bar
3. Seal two specimen of timber
Theory
When the timber test specimen is subjected to compressive load then the compressive stress in given by
Б = (P / A) Kg/mm2
Where,
Б = compressive stress is given by kg/mm2
P = load at which specimen failure in kg standard
A = cross-sectional area of timber specimen in mm2 ordinary
Objective
Timber is most widely used traditional structure material. Timber joints in roof trusses wooden flooring is subjected two compressive load. The properties of timber is depend upon the direction of grains.
Procedure
1. Measure the actual dimensions of timber specimen.
2. Place specimen along the grains on the platform of universal testing machine.
3. Fix the dial gauge for recording deflection.
4. Apply the load gradually note the maximum load at which the specimen fails.
5. Repeat the above procedure for the specimen across the gauge.
6. Inter the observations in observation table.
Diagram
Compressive Testing Machine
Conclusive
According to I.S. 2629 – 1966 for standard and ordinary groups of timber is given by following
Group | Б N/mm2 | Compressive stress parallel to grain | Compressive stress perpendicular to grain | ||
Ultimate | Permissible | Ultimate | Permissible | ||
standard | 28 | 28 | 7.0 | 4.4 | 2.5 |
ordinary | 26 | 26 | 6.4 | 3.5 | 2 |
E > 9800 for standard group
E > 5600 for ordinary group
It is found that the specimen which is use for testing is form A group.
Observation
Sr. No. | Position of specimen | Cross-sectional area in mm2 | Cross-sectional area in mm x mm | Load at failure in kg | Compressive standard in kg/mm |
1 | Along fiber | 2500 mm2 | 50 x 50 mm2 | 15000 kg | 6 kg/mm2 |
2 | Along fiber | 2500 mm2 | 50 x 50 mm2 | 3000 kg | 1.2 kg/mm2 |
