Modeling the coupling effect of CLT connections under bi-axial loading

This paper presents the modeling of coupling effect of tension and shear loading on Cross Laminated Timber (CLT) connections using a finite element based algorithm called HYST. The model idealizes the connections as a “Pseudo Nail” - elastoplastic beam elements (the nail) surrounded by compression-only spring elements (steel sheath and wood embedment). A gap size factor and an unloading stiffness degradation index of the spring elements under cyclic loading were integrated into the optimized HYST algorithm to consider the coupling effect. The model was calibrated to compare with 32 configurations of CLT angle bracket and hold-down connections tests: in tension with co-existent constant shear force, and in shear with co-existent tension force. The results showed that the proposed model can fully capture the coupling effect of typical CLT connections, considering strength degradation, unloading and reloading stiffness degradation, and pinching effect. The model provided a useful tool for nailbased timber connections and a mechanism-based explanation to understand the hysteretic behaviour of CLT connections under bi-axial loading

Influence of furniture on the modal properties of wooden floors

Structure-borne vibration and low-frequency re-radiated noise from internal and external sources cause annoyance for inhabitants in dwellings. A key parameter in the prediction of vibration and noise levels is the modal parameters of the floors in a building, since vibration and sound levels increase when natural frequencies of the floor coincide with the excitation frequencies of a source, e.g. monoharmonic vibration of unbalanced rotating machinery and appliances or HVAC system—or traffic induced ground vibration propagating into the building. This paper has focus on wooden floors built as an assembly of particleboard and timber joists. Such floors constitute horizontal divisions in many dwellings—both older, traditional buildings and new lightweight buildings. The analysis concerns the impact of furniture placed on a floor with otherwise known properties. Given the small mass of a traditional wooden floor, the presence of furniture can be expected to change the modal properties of the floor significantly. The finite-element model, developed for the present analyses, accounts for uncertainty in the position of the furniture, and the analysis addresses the importance of the elevation of the mass above the floor regarding the natural frequencies and the related modes of vibration