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2.2.15 Material and product properties (EC0,4.2)

As in the case of actions, the properties of materials or products are also represented by characteristic values.

When dealing with timber or wood-related properties the characteristic value will be either the 5th-percentile value or the mean value. The 5th-percentile value will apply to strength-related properties and the mean value will normally be used for stiffness-related properties. The exception to this rule is when stiffness-related functions are used in the derivation of a strength property; for example when used for the evaluation of the critical bending strength of a timber beam, in which case the 5th-percentile value rather than the mean value is used.

Characteristic values of the properties of timber and some of the commonly used wood-related products in timber design are given in Chapter 1.

2.2.16 Structural analysis (EC0, 5.1) 2.2.16.1 General

EC0 gives no specific guidance on the method(s) of structural analysis to be used in design other than to require that the structural models be appropriate for the limit state considered, be able to predict behaviour with an acceptable degree of accuracy, and be based on established engineering theory and practice.

When analysing a structure, several alternative methods of analysis are possible and these are outlined in 2.2.16.1.1 and 2.2.16.1.2.

2.2.16.1.1 Linear elastic analysis

It is based on linear stress/strain and moment curvature laws:

(a) First-order analysis without redistribution. This is performed on the initially defined geometry of the structure and its elements without any adjustment of internal forces/moments due to redistribution. It is the basis of most first-order linear elastic analysis computer programs (Figure 2.1a).

(b) First-order analysis with redistribution. This is performed on the initially defined geometry of the structure and its elements but internal forces/moments are adjusted without further calculation to also adjust rotations and check rotation capacity.

(c) Second-order analysis. This is performed on the geometry of the deformed structure (Figure 2.1b).

2.2.16.1.2 Non-linear analysis

It is based on a non-linear stress-strain relationship as shown in Figure 2.2:

(a) First-order analysis. This is performed on the initially defined geometry of the structure.

(b) Second-order analysis. This is performed on the geometry of the deformed structure.

The following descriptions are commonly associated with non-linear analyses incorporating plastic behaviour:

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