Experimental investigation and beam-theory-based analytical model of cross-laminated timber panels buckling behavior

This paper investigates the buckling behavior of three-layered cross-laminated timber (CLT) panels, from both the experimental and analytical standpoints. Two different series of specimens are considered: the homogeneous ones, which are entirely made of beech, and the hybrid ones, whose inner layers are made of Corsican pine. The experimental tests aim to evaluate the failure limit loads of the specimens, when loaded by an increasing compression tip force. The analytical formulation is first obtained for a panel with a generic number of layers and after it is specialized for a three-layered panel. Timber layers are modeled as internally constrained planar Timoshenko beams linked together by adhesive layers, which are modeled as a continuous distribution of normal and tangential elastic springs. A closed-form solution of the buckling problem is obtained. The achieved Eulerian critical load of CLT panels depends on two parameters, which account for (1) the interaction between timber layers (due to the glue tangential stiffness) and (2) the rolling shear stiffness of the inner layer. Three different failure criteria are introduced to estimate the limit load. Finally, the analytical limit loads and the experimental ones are compared.