Effect of concentrated impulse loading (impact) on massive, glulam, and cross-laminated timber beams

In this study, massive, glulam, and cross-laminated timber beams of rectangular cross-section were examined under a concentrated impulse loading (impact). The task addressed was to determine and compare the deformation and dynamic characteristics of beams made of different types of timber under short-term impact. During experimental studies, dependences of displacements over time were established; oscillation oscillograms were constructed; spectral analysis was performed, and the frequencies of free oscillations (fMT,exp = 75 Hz, fGLT,exp = 73 Hz, fCLT,exp = 67 Hz) and logarithmic damping decrements (βMT,mean = 0.222, βGLT,mean = 0.100, βCLT,mean = 0.092) were determined for each type of beam. It was found that a cross-laminated timber beam is characterized by the lowest deformation resistance and the lowest oscillation damping rate. Glue-laminated timber (glulam), in comparison with solid timber, demonstrates a smaller maximum displacement and a lower oscillation damping rate. The results are attributed to the peculiarities of internal structure of the materials, the orientation of the fibers, the presence of adhesive layers, and the nature of the interlayer interaction, which significantly affect the stiffness, damping properties, and distribution of impact energy. A distinctive feature of the findings is the experimentally confirmed comparison of the dynamic response of beams made of different wooden based materials under the same loading conditions, which made it possible to reasonably assess their effectiveness under the action of impulse influences and solve the research problem. This study's results could be used in the design of timber load-bearing elements of buildings and structures subjected to dynamic or impact loads, as well as to refine calculation models, determine dynamic coefficients, and assess the effectiveness of using solid, glued, and cross-glued wood