Finite Element modelling of dowel-type connections in CLT Structures - from timber embedment behaviour to CLT shear walls

Cross-Laminated Timber (CLT) is a pre-engineered timber product that has gainedmuch popularity over the last three decades as a sustainable construction material.CLT has excellent mechanical properties, and connections between CLT elementsand other structural elements in CLT structures are often critical in the engineeringdesign. The aim of this thesis is to develop a Finite Element Method (FEM)model for connections with dowel-type fasteners in CLT structures. Through athorough analysis from the embedment behaviour of timber to the simulation ofCLT structures with connections, this thesis aims to deepen the understandingof the load transfer and deformation behaviour of connections. Papers I and IIinvestigate with own and previous experiments the embedment behaviour ofdowel-type fasteners in timber and CLT. A non-linear analytical spring model forthe prediction of CLT embedment behaviour from the embedment behaviour ofthe constituent layers is proposed and shows good agreement with experiments.A Finite Element Method (FEM) model for the non-linear force-displacementbehaviour of single-fastener CLT connections is presented in Papers III andIV. A ‘Beam-on-Foundation’ (BoF) model is implemented in the FEM modelfor simulating the connection behaviour. The BoF model is validated withexperiments on steel-to-CLT and concrete-to-CLT connections, before it is usedto investigate the influence of various parameters on both the strength and slipmodulus of CLT connections. In Paper V, several single-fastener BoF models areintegrated into a multiple-fastener CLT connection model. The FEM model isvalidated with experiments on laterally loaded multiple-fastener steel-to-CLTconnections and used to investigate the influence of various parameters on thestrength and slip modulus of multiple-fastener CLT connections. From theresulting database, a design equation for the group effect in the slip modulusof steel-to-CLT connections with multiple-fasteners is derived. In Paper VI, theFEM model is applied to simulate angle bracket and hold-down bracket CLTconnections, as well as full-scale CLT shear walls with multiple connections.Due to the integrated BoF models, the FEM model provides insight into theload distribution between various connections. The developed FEM model is aneffective tool for the prediction of the force-displacement behaviour, the ductilestrength and the slip modulus of CLT connections with dowel-type fasteners.As it is implemented using a parametrised python script, the FEM model ishighly adaptable to accommodate numerous material and geometrical parameters.In addition to the effectiveness of the developed FEM model, the study alsohighlights the need for further developments in the simulation of the interactionof loading conditions and experimental validation.