Timber-timber composite (TTC) connections and beams: An experimental and numerical study

Abstract

Push-out experiments on cross-laminated timber (CLT) panels connected to laminated veneer lumber (LVL) were carried out and load vs slip response of the CLT-LVL composite joints were obtained and stiffness, peak load, and ductility of the timber-timber composite (TTC) connections were evaluated and reported. Moreover, full scale 6.0 m long CLT-LVL beams with the tested shear connectors were fabricated and tested under four-point bending set up and the load vs mid-span deflection as well as load vs end slip graphs of the TTC beams were provided. Furthermore, the failure mode, service stiffness and load-carrying capacity of the CLT-LVL beams were studied. The main variables in the experimental program were the type of shear connectors (i.e. single or double threaded screws, dowels embedded in cementitious grout or epoxy pocket), size and installation angle of the screws, CLT panel thickness and orientation of the load with respect to CLT panels (i.e., loaded parallel || or perpendicular ⊥ to the outermost timber lamellae). A continuum-based finite element (FE) model for the TTC beams was developed and analysed using ABAQUS software. It was shown that the FE models can capture the load–deflection and peak load of the TTC beams with reasonable accuracy. The validated FE model was employed to conduct a parametric study and investigate the effect of CLT slab segmentation on the stiffness and load-carrying capacity of the CLT-LVL composite beams. Lastly, the adequacy of the existing simple analytical model for predicting stiffness and load-carrying capacity of the TTC connections and beams was demonstrated.