Exact Stability Calculation for Timber Beams and Columns

A derivation is given of simplified, exact stability design rules according to limit analysis, applied to timber beam-columns. These rules are lacking but are necessary to be able to provide real and calculable reliability as is required according to European pacts and laws. Necessary therefore are the obtained exact combined bi-axial bending, compression and shear strength equations with the exact equilibrium equations under biaxial loading. As for other materials the elastic-full plastic limit design approach is applied, which is already known to precisely explain and predict uniaxial bending strength behavior. The strength derivation is based on choosing the location of the neutral line. This provides the stress distribution in the beam cross section in the ultimate state for that case, providing the possibility to calculate the associated ultimate bending moments in both main directions combined with the ultimate normal- and shear forces.

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