Influence of support conditions on vibrational performance of cross laminated timber floor systems
University of New Brunswick
Cross-laminated timber (CLT) is a recent engineered wood material produced in a variety of thicknesses and lengths and used in for floor systems. The design of CLT floors has specific support and connection details that require evaluation on the performance of these mass timber structures. The serviceability criterion is one of the primary considerations for the adequate design of timber floor construction. Proposed design procedures consider the first natural frequency and deflection parameters. Nevertheless, there are many uncertainties concerning the factors that influence these parameters in a CLT floor structure. The main focus of the research project was on the influence of end support condition on vibration performance of CLT floor. The support condition was characterized by the rotational stiffness at the supported edges of the CLT floors. A second interest was the performance of CLT floors when supported in a double-span configuration. Experimental work was conducted to evaluate these influences. In addition, finite element analysis (FEA) modelling was conducted to supplement the experimental work. To obtain material property input into the FEA models, laboratory experiment was conducted to characterize the rotational stiffness of CLT panels measured with vibration and CLT material properties determined under static tests by CLT strips cut from the CLT panels. The results demonstrated the influence of the rotational stiffness tested with double-span setup on the first natural frequency and static deflection of the CLT floors. Also, the FEA modeling proved to be effective in predicting natural frequencies and deflections of CLT floors, with accuracy improving with the use of orthotropic material properties compared with isotropic properties. The presence of panel-to-panel joints in CLT floor was found to have a significant impact on the transverse system stiffness of CLT floor and should be properly accounted for in design if two-way orthotropic plate model is used. It is recommended that further research be pursued on floors supported on all four sides and by beams or columns, and multiple-span floors.