Determining elastic constants of full-size cross laminated timber panel supported on four nodes using a vibration method

Abstract

The objective of this study was to determine the elastic constants and fast identify the modal parameters of the first nine modes of full-size cross laminated timber (CLT) panel under four-node support using a vibration method. Firstly, the theoretical basis of vibration determination for elastic constants (modulus of elasticity in the length and width directions of the panel, Ex, Ey; in-plane shear modulus of the panel, Gxy) of full-size CLT panel under four sides completely free (FFFF) and four-node support boundary conditions (BCs) were established. Then, full-size larch CLT panels were used to experimental modal analysis and elastic constants vibration test under FFFF and four-node support BCs. Modal parameter (modal shapes and modal frequencies) and elastic constants of full-size CLT panel under two BCs were comparison analyzed to verify the feasibility of determination elastic constants of full-size CLT panel under four-node support. And then, a three-point excitation testing method for fast identification of modal parameters of the first nine modes for full-size CLT panel supported on four nodes was proposed and verified the feasibility of this method. The results indicated that the mode shapes can be used to measure Ex, Ey and Gxy of full-size CLT panel, that the modes (2, 0), (0, 2) and (1, 1) under FFFF BC and the modes (2, 0), (0, 2) and (1, 2) under four-node support BC, respectively. Meanwhile, the modes (m, n) (m = 2 or n = 2) under FFFF and four-node support BCs are in good agreement in terms of mode shapes, and the frequencies are approximately equal. It is verified the proposed assumption that mode (m, n) (m = 2 or n = 2) of full-size CLT panel under these two BCs is the same from the perspective of both modal shape and its natural frequency. At the same time, it is feasible to rapid identify modal parameters of the first nine modes and the determination of elastic constants for full-size CLT panel supported on four nodes using the three-point excitation testing method.