Strength and Adsorption of Energy

As one might anticipate, the two key characteristics influencing the strength of clearwood are density and MFA. However, a further effect is that of branches/knots on the local strength in their immediate vicinity. Discussion on the role of knots is deferred to Chapter 10. 

From these observations, Reiterer et al. (1999) conclude that trees and branches require  

It is not possible to maximize all these eriteria at onee (Table 6.2). Thus the tree is optimized (compromised) to aehieve different goals at eertain times during its growth, while concurrently laying down wood of different densities and MFAs in different parts of the tree. 

Grading for structural markets is generally non-destruetive and relies on eorrelations with wood stiffness. First the stiffness of the member is measured, and from that the strength is estimated. 

Flowever in timber construetion work to failure is of less concern except with pit props, poles and fencing. In construction the metal connectors - bolts, nails and metal plates - are designed to absorb any large deformations that arise in cyclones or earthquakes. The timber members are proteeted by the duetility of the connectors so wood stiffness and strength are more eritieal than work to failure. 

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