Diagonal laminated timber—Experimental, analytical, and numerical studies on the torsional stiffness

This paper deals with the development and implementation of diagonal laminated timber (DLT), a composite timber product, consisting of individual layers which are rotated to each other to a certain angle to increase its torsional stiffness. For the investigation we chose a specific DLT characterized by layers arranged at angles of ±45◦ respectively ±30◦ (±60◦). The adjusted layup increases stiffness properties and provides ideal product properties for plates under biaxial bending. The load-bearing behavior and efficiency of diagonal laminated timber was investigated by means of theoretical and experimental investigations. The applied parametric numerical models explain the influence of the layer arrangement as well as the influence of width and thickness of the laminations on the torsional stiffness. The results prove a considerable increase in torsional stiffness of diagonal laminated timber compared to conventional cross laminated timber. This renders DLT an interesting option for floor systems which are governed by serviceability limit states such as deflections or vibrations.