Abstract:
Timber is a commonly used construction material in Sri Lanka. But the strength
parameters of locally available non-class timber are not available. In this study main objectives are to
determine strength parameters and physical properties of selected local timber materials and to develop a
strength class classification with their possible applications in the construction field. Different strength
parameter tests are conducted in bending, compression (grain parallel and perpendicular), tension
(parallel to grains), and shear perpendicular to grain. In addition, durability, fire resistance tests and
physical properties such as dry density, bulk density, and water absorption were carried out. For those
tests BS 373 (1957) and EURO CODE 5 were used as references. Average moisture contents of nonclass
timber specimens were around 12%, modulus of elasticity varies 3200 MPa - 13,000 MPa, modulus
of rupture varies 37 MPa – 85 MPa, dry density varies 600 kg/m3 - 900 kg/m3. Strength parameters at
serviceability limit, mainly compressive strength at parallel to grains varies 13 MPa - 45 MPa, and
compressive strength perpendicular to grains varies 3 MPa – 22 MPa in most of the non-class timber
species. Shear capacity of perpendicular to graons of non-class timber materials varies 0.9 MPa - 5 MPa
at serviceability limit. Tension capacities of timber materials vary 35 MPa - 100 MPa and charring rate of
timber species varies 0.25 mm/min - 0.8 mm/min. Similarly other test parameters were investigated and
presented in the paper. Finally identified non-class timber species were classified according to available
strength classes and proposed suitable applications for each type.
