Numerical and Analytical Models for Predicting Load-Carrying Capacity of Timber–Concrete Notched Connections

Timber-concrete composite (TCC) structures combine the natural aesthetic and sustainability of timber with the strength and fire resistance of concrete, offering numerous structural, environmental, and economic advantages. A crucial element in the performance of TCC structures is the connection between concrete and timber which determines the effectiveness of the composite action. One type of connection known for its high composite efficiency and superior strength is the notched connection. However, existing analytical models for the design and assessment of notched connections are limited and often based on oversimplified assumptions. This study presents both numerical and analytical models to predict the load-carrying capacity and failure mode of TCC notched connections. A finite element (FE) modeling procedure is introduced in which concrete is represented using a smeared hybrid fixed-rotating crack model, whereas timber is treated as a fixed orthotropic material. Appropriate constitutive models are adopted to capture the nonlinear material behavior, with special attention given to accurately represent the interface between concrete and timber. After validation of the FE model against various pushout tests collected from the literature, a series of parametric studies are conducted to evaluate the influence of key design parameters on the connection behavior. Using the parametric study results and equilibrium conditions, closed-form equations are derived to approximate nonlinear and multiaxial stress conditions in the notch, forming the basis of the proposed simplified analytical model. The proposed model is verified against experimental and FE analysis results and further evaluated against the Eurocode standard. It is demonstrated that the proposed model predicts the connection capacity with good accuracy, often outperforming the Eurocode, and can therefore be used to improve the design and assessment of TCC structures.