
Strength properties
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In general terms, steel and concrete are both homogenous, being uniform in structure, and isotropic, having the same strength properties in all directions. However, in order to understand how timber behaves as a structural material it is necessary to understand that it has different strength properties in the longitudinal and transverse directions, and that it is the arrangement of the cells in timber that determine its strength and behaviour under different loads. Understanding the structure of wood will explain, for example, why it is up to 40 times stiffer in the longitudinal direction than the transverse direction.
Timber has different strength properties in the longitudinal and transverse directions, and it is the arrangement of the cells in timber that determine its strength and behaviour under different loads.
Many factors affect the strength properties of timber: for example material properties, and climatic and environmental growth conditions.
The Modulus of Elasticity (MOE) and the Modulus of Rupture (MOR) are the two most important factors in the way timber responds to stress in the application of a load.