Timber-concrete composite (TCC) floor systems have gained interest as a sustainable alternative to concrete floors, particularly in applications requiring longer spans than typical timber floor systems. By connecting timber elements to concrete slabs with shear connectors, TCC systems increase the structural stiffness and improve vibrational characteristics while maintaining a reduced carbon footprint. This study investigates the dynamic performance of a 6 m span glued-laminated timber-concrete composite (GLTCC) floor by means of forced vibration testing and finite element (FE) simulations. Experimental results revealed a first natural frequency of 13.25 Hz, surpassing the 8 Hz requirement specified in Eurocode 5, and a damping ratio of 3.34% for the first mode – close to recommended values for TCC floors with a floating screed. The FE model closely predicts the experimentally measured frequencies and mode shapes, demonstrating the validity of the numerical approach. Parametric studies further highlight the importance of support conditions and connection properties. Continuous supports such as walls or sufficiently stiff beams help maintain higher frequencies, while column supports reduce the frequency in certain modes. Enhanced connection stiffness, as achieved by notches, raises the overall dynamic response, whereas less stiff alternatives, such as screws, lead to reduced composite action and lower frequencies. Overall, these findings confirm the effectiveness of GLTCC floor systems for medium-span applications and highlight the need for careful consideration of support conditions and connection details to ensure optimal vibrational performance.

The lateral behaviour of cross-laminated timber (CLT) shear walls is mainly governed by the non-linear behaviour of connections. Commonly, dowel-type connections that exhibit a ductile force-displacement behaviour are used in the shear angle bracket and hold-down bracket connections. The numerical investigation of CLT shear walls presented herein integrates the so-called Beam-on-Foundation (BoF) model to simulate the ductile connection behaviour in FEM models of shear wall connections and full-scale CLT shear walls. The comparisons of simulation results with experimental data, as well as with engineering design equations and analytical models at the scale of the connection and the shear wall, show reasonable agreement. Due to the integrated BoF model, the shear wall model provides insight into the load distribution between connections, as well as between fasteners within connections and the load distribution over the thickness of the CLT. Despite a need for further investigations, the results of this study highlight the potential of the modelling approach to enhance the understanding of the contribution of the components of the CLT shear wall to its overall structural behaviour. This is indispensable for a safe and reliable design of CLT structures.

This study generalises an upscaling modelling approach, originally proposed for connections loaded parallel to the grain, to account for in-plane multiaxial loading of connections. The main objective is to evaluate how the combination of internal forces affects the brittle response of dowelled connections. A Beam-on-Foundation model is implemented to obtain the nonlinear load-displacement behaviour of single fasteners. Such information is assigned to coupled nonlinear springs located at the connection shear planes in a multiple-fastener connection model to capture the stresses in the timber member between the fasteners. The onset of cracks along the grain direction is evaluated using the mean stress approach. The numerical model shows a strong correlation with prior experimental findings and offers an efficient method for predicting crack initiation in multiple-fastener connections. Additionally, limit curves for the interaction of normal force and bending moment are provided for an exemplary connection layout, considering different slenderness ratios and brittle and ductile failure.

For the design of robust timber buildings, it is essential to develop reliable methods to assess possible brittle failure of connections. Therefore, this paper proposes a three-step modelling approach to predict: (i) the load–displacement behaviour of individual dowels, (ii) the stress distribution in the timber matrix, and (iii) the brittle failure of the timber, in connections with laterally loaded steel dowels. The local nonlinear behaviour of single-dowel connections was determined with a Beam-on-Foundation model and subsequently assigned to nonlinear springs located at the multiple-dowel connection shear planes. The timber member and the steel plate were modelled using 3D shell elements with linear-elastic orthotropic and isotropic material properties, respectively. The interaction between dowels and shell elements was characterised by hard contact and friction. A post-processing module, based on linear elastic fracture mechanics, was implemented to evaluate potential cracks along the grain direction through the mean stress approach. The numerical model aligns well with previous experimental results and provides a novel approach for the prediction of crack initiation based on a realistic load distribution in multiple-dowel connections, while taking advantage of high computational efficiency.

Ductile timber structures are mainly realised using dowel-type connections, which exhibit non-linear force–displacement behaviour that is not directly proportional to the number of fasteners. This so-called group effect has mainly been studied as regards strength, while the group effect in the slip modulus is less investigated. A Beam-on-Foundation (BoF) model for the local behaviour of each fastener is integrated into a multiple fastener steel-to-cross-laminated timber (CLT) connection model, considering CLT layer specific non-linear embedment behaviour. The BoF model for each fastener is kinematically coupled to the surrounding timber matrix, modelled by shell elements with orthotropic linear-elastic material properties. The resulting adaptive connection model is used to predict both shear capacity and slip modulus of steel-to-CLT connections with multiple fasteners and to investigate group effects. A comparison of experimentally-determined and model predicted shear capacity and connection slip modulus showed good agreement. The validated model was applied to study, in addition to the number of fasteners parallel and perpendicular to the outer layer’s fibre direction, the influence of fastener diameter, fastener spacing, loading direction, timber density and steel plate thickness on the load distribution between the fasteners and the overall connection behaviour. The dataset from the parameter study was then exploited to derive a design equation that predicts the group effect in the slip modulus of CLT connections.

To increase and optimize the use of wood in structural elements, a deep understanding of its mechanical behavior is necessary. The transverse material properties of wood are particularly important for mass timber construction and for utilizing wood as a strengthening material in timber connections. This study experimentally determined the stiffness and strength of Scots pine wood under compression perpendicular to the grain and rolling shear loading, as well as their dependence on the annual ring structure. A previously established biaxial test configuration was employed for this purpose. The modulus of elasticity in the radial direction was found to be about twice that in the tangential direction (687 vs. 372 N/mm²), although the strength in the tangential direction (5.19 N/mm²) was comparatively higher than that in the radial direction (4.70 N/mm²). For rolling shear, especially for the rolling shear modulus, a large variation was found, and its relationship with annual ring structure was assessed. The obtained RS modulus ranged from 50 to 254 N/mm², while RS strength was found to be between 2.14 and 4.61 N/mm². The results aligned well with previous findings.

In this study, a numerical model that aimed to predict the strength and stiffness, of a single laterally loaded mechanical fastener in steel-to-cross laminated timber (CLT) connections using a Beam-on-Foundation (BoF) model, is presented. The BoF model was used to predict the ductile failure modes of steel-to-CLT connections and considered the layered structure of CLT. When compared to the European Yield Model (EYM), the BoF model was found to be advantageous as it not only predicted the strength but also the stiffness of the connections. A comparison of the slip modulus and strength from BoF model simulations of experimental tests carried out on steel-to-CLT connections showed good agreement with the experimental results. Using the BoF model, the influence of; (i) density, (ii) deck layer orientation, (iii) embedment behaviour, (iv) dowel diameter, (v) steel plate thickness, and (vi) embedment length, on steel-to-CLT connections was investigated in a parameter study. The results presented herein highlight the benefit of the BoF model that considers CLT layer specific embedment behaviour in determining the shear capacity and stiffness of steel-to-CLT connections.

Cross-laminated timber (CLT) has become popular as a construction material and the design of CLT connections is typically based on empirical equations with an average embedment strength of the wood-based product. The experimental study presented herein aims at enhancing the understanding of the relationship between the CLT embedment behaviour and the single layers it is composed of. Non-linear embedment stress–displacement relationships were measured in 244 full-hole and half-hole embedment tests on structural timber boards as well as on CLT produced of parts of the same boards. Three different fasteners, namely a steel dowel with a diameter of 12 mm and the threaded part of screws with a nominal diameter of 6.5 mm and 10 mm, were studied. The design of the experiments allowed to validate a simple mechanical model with parallel springs for the CLT, which showed good agreement with experiments. In addition to a validation of the non-linear spring model, this unique experimental data-set is further exploited in a comparison with empirical equations and for the derivation of a non-linear embedment ratio, between parallel and perpendicular to the grain embedment stresses, over the displacement. Knowledge of the relationship between the non-linear embedment behaviour of the single layers and the CLT element can be further exploited in the engineering design and numerical modelling of CLT connections with dowel-type fasteners.