Quality assessment of stiffness and load-carrying capacity of composite connections is of great importance when it comes to designing timber–concrete composite structures. The new European regulation intended explicitly for timber–concrete structures has made a significant contribution to this field, considering that until today there was no adequate design standard. Due to the proposed general expressions for determining the stiffness and load-carrying capacity of composite connections made with dowel-type fasteners, which are incapable of describing most of the commonly applied fasteners, engineering, and scientific practice remained deprived of a quality assessment of the essential mechanical properties of the connection. In order to overcome this problem, this paper proposes a numerical model of the connection suitable for determining the whole load–slip curve, allowing it to estimate the stiffness and load-carrying capacity of the connection. The model was developed by considering the non-linear behavior of timber and fasteners, which is determined through simple experimental tests. For the numerical model validation, experimental tests were carried out at the level of the applied materials and on the models of the composite connection. Through numerical simulations, analysis of obtained results, and comparison with experimental values, it can be confirmed that it is possible to simulate the pronounced non-linear behavior of the timber–concrete connection using the proposed model. The estimated values of stiffness and load-carrying capacity are in agreement with the conducted experimental testing. At the same time, the deviations are much less than the ones obtained from recommendations given by the new regulation. Additionally, apart from evaluating the value and the simulation of the complete curve, it is possible to determine local effects, such as the crushing depth in timber and concrete, the fastener’s rotation, and the participation of forces in the final capacity of the connection.

Timber-concrete composite structures are already applied more than 80 years in engineering practice, went trought the intuitive problem solution to the fully prefabricated hybride assemblies for dry building. The development path of timber-concrete composites was always followed by extensive theoretical and experimental research, whose results were successfully implemented in practice, i.e. on the market, but till presence didn't result in modern designer's code. In expectation of new European codes for timber-concrete composites, the objective of the paper is to provide a comprehensive review of available standards provisions and recent conclusions from literature. The key issues for practical design are highlighted and ilustrated on the example of glulam composite arch bridge structure with concrete deck, according the Eurocodes.

The analysis and design of composite timberconcrete (TCC) structures, where the connection of the constituent elements is achieved by dowel type fasteners, is a complex task due to taking into account the slip of the coupling means, i.e. interlayer slip on the contact surface of two materials. The application of simplified procedures and methods in the analysis of the TCC system is a convenient and desirable way of design that enables efficient tool for engineering practice. Widespread simplified calculation procedure, so called 'γ-method', is adopted in EN 1995. Methods based on differential or variational formulation are commonly applied when software for structural analysis are used. Galerkin's and Ritz's methods for analysis and design of TCC systems in the case of simply supported beam loaded with uniformly distributed load are shown in this paper. The selection of trial functions that describe the problem of elastic composite action as well as their influence on the final results were analyzed. For the purposes of numerical analysis, based on the proposed numerical models, several codes are written in MATLAB. The model applied in analysis by Galerkin's method, that best describes the problem of elastic coupling, was chosen for further comparative analysis with experimental data.

The second generation of Eurocode 5 is in preparation and has not yet been adopted, so the calculation of the load-carrying capacity of timber-steel connections is based solely on the rules of the first generation. Currently, load-carrying capacity is determined using expressions for thin or thick steel plates. For cases in between, linear interpolation is used. The thickness and mechanical properties of the steel plate significantly influence the behaviour of the timber-steel connection, which is why research in this field focuses on improving the expressions for the connection capacity. The aim is to define the failure modes more precisely and determine the connection capacity more accurately. This paper shows how Johansen’s expressions for timber-timber connections can be adjusted for steel-timber connections by accounting for the previously mentioned parameters.

Eurocode requires the consideration of geometric imperfections. Imperfections can be considered directly, as is the case in GNIA and GMNIA analyses. Recent studies propose various methods for obtaining the governing imperfection, yet they rarely justify the criterion used to determine the buckling resistance from the nonlinear load-displacement curve, nor do they consider how the choice of criterion affects the assessed imperfection sensitivity. This paper presents criteria for determining buckling resistance in GNIA analysis, applied to and compared on two frames whose imperfections were modelled directly using an exhaustive search of imperfection combinations. The results show that the choice of criterion does not merely affect the assessed resistance value, it fundamentally changes the identification of the governing imperfection and its shape, with different criteria potentially identifying entirely different combinations as the most unfavourable. Consequently, the assessed imperfection sensitivity of the frame also depends significantly on the chosen criterion.