EXPERIMENTAL AND NUMERICAL INVESTIGATION OF CLT PANELS WITH DIFFERENT ORIENTATIONS OF TRANSVERSE LAYERS

This paper presents an experimental and numerical investigation of two configurations of panels made of locally produced cross-laminated timber (CLT) with different orientations of laminations (boards) within transverse layers – conventional and modified orientation. Modified orientation refers to laminations of transverse layers positioned at an angle of ±45° in relation to longitudinal layers. The expected advantages of modified CLT are improved mechanical performance, more efficient use of resources considering material properties, reduction in variability of characteristics within the panels and increase in shear resistance. In addition to experimental testing, numerical analysis based on finite element method was performed and successfully validated in order to serve as a more efficient tool for CLT panel investigation and optimization

Determination of mode I fracture properties of European spruce

In this paper an efficient procedure for obtaining a cohesive law for Mode I timber fracture (crack opening), based on the Double Cantilever Beam (DCB) tests is given. DCB tests were performed on ten European spruce specimens in order to determine the energy release rate vs crack length (R curves). Two crucial parameters – crack length during the experiment and the crack tip opening displacement were obtained using 2D Digital Image Correlation (DIC) technique. In order to determine accurate fracture resistance (R curve), procedure which includes calculating cumulative released energy was employed. The cohesive law for Mode I fracture of wood was obtained by differentiation of the strain energy release rate as a function of the crack tip opening displacement. This cohesive law is further implemented in the successful numerical modelling of failure modes in large-scale end-notched glulam beams which were experimentally tested in four-point bending configuration.