Load-bearing capacity of imperfection-sensitive timber members under combined bending and compression

This thesis discusses the load-bearing behaviour of imperfection-sensitive timber members under combined bending and axial compression. As there is a fl uent transition between the stability phenomena of fl exural buckling and lateral torsional buckling, the stability phenomena were studied holistically. Imperfection measurements in 23 timber buildings, fl exural buckling tests on beech LVL columns, and lateral torsional buckling tests on glulam beams were conducted. Through analytical investigations, the knowledge of the theoretical background of the stability behaviour was broadened. For the detailed study of the infl uence of structural and geometrical imperfections and combined bending and axial compression, numerical models were developed and employed in extensive parameter studies and Monte Carlo simulations. Thereby, the nonlinear Nx,c-My,1-interaction of the kc-km-method was validated, and consistent equivalent imperfections for design were derived. Additionally, it was demonstrated that the shear and compressive plasticising and the cross-sectional warping due to shear can have a signifi cant infl uence on the load-bearing capacity. Design proposals were developed that modify and extend the design rules in EN 1995-1-1, in favour of a more reliable, consistent, and economical design. For the fi rst time, by means of comprehensive experimental, analytical, and numerical investigations, fl exural buckling and lateral torsional buckling of timber members were combined in consistent analysis and design models. This provides a sound foundation on which subsequent research can build and expand.