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Vibration performance of a one-way simply supported timber-concrete composite (TCC) floor section has been studied using analytical as well as numerical methods. Focal points have been verification and validation of results from analytical and numerical calculations of vibration response based on experimental data. For the analytical calculations, floor bending stiffness and vibrational response are determined from methods proposed in the current and revised versions of Eurocode 5. The numerical calculations based on the finite element (FE) method are done using 3D solid elements with orthotropic material parameters. When comparing the results of the FE analysis, better agreement with the experimental data is reached for the fundamental frequency when 3D solid elements are used rather than 3D beam elements. Furthermore, better agreement with the experimental data is reached for RMS acceleration by FE analysis rather than the method based on Eurocode 5. For detailed analysis, the authors suggest performing dynamic FE analysis and calculating vibration response from the TCC floor's modal responses as eigenmodes and natural eigenfrequencies below 40 Hz. For future studies, it is recommended that the verification of vibration response may be accomplished by applying standard EN 16929. [ABSTRACT FROM AUTHOR]

This study aims to present a multi-criteria decision analysis (MCDA) for comprehensive performance evaluation of the alternative design of timber–concrete composite (TCC) floor system. Considered objectives are serviceability and sustainability performance with associated criterion as (1) comfort class regarding springiness and vibrations, (2) architectural quality with associated criterion as open spaces, (3) environmental aspect with associated criterion as CO2 emissions and (4) cost aspect with associated criterion as the total costs. Analytical Hierarchy Process (AHP) and Complex Proportional Assessment (COPRAS) as the methods in the multi-criteria analysis have been combined for (1) determining the weighting of criteria based on the survey results, (2) verifying the consistency ratio of decision matrix made by experts and (3) for ranking and selecting the optimal concept design among design candidates. According to the results, the TCC floor with the span length of 7.3 m belonging to comfort class A has got the highest ranking. However, sensitivity analysis indicates that the TCC floor with a 9.0 m span length belonging to comfort class A shall be selected as the optimal concept design. The study contributes by developing a complete concept design tool for TCC floor systems using AHP combined COPRAS methods to handle both beneficial and non-beneficial criteria. [ABSTRACT FROM AUTHOR]

This study focuses on the evaluation of the mechanical behavior of two types of connections for intended use in rural Timber-Concrete Composite traffic bridges. The two connection types used were the "X" type connection - XD and the dowel type connection - PD. Firstly, static shear tests in small-scale specimens were performed in both connection types and higher results were obtained for the XD series, both for stiffness and load carrying capacity. Secondly, the PD connection was chosen, based on practical and economical aspects, for further testing also in small-scale specimens, including cyclic tests. The influence of the number of cycles in the connection stiffness and load carrying capacity was evaluated. It was concluded that the load carrying capacity increased after the application of a pre-defined number of load cycles and that the connection stiffness increased 80,6% and 34,1% after 10000 and 1000 cycles, respectively, for different applied load levels. Also the increase of load level in the cyclic tests affected the performance of the connection, leading to a decrease in stiffness. [ABSTRACT FROM AUTHOR]

• The connection system is strong and also has the ability ductility. • The composite effect is evident when activating the connection system. • The design model, γ-analysis, understands the performance of the structure. This paper presents results of an experimental study implemented with the goal to verify performance of an innovative type of a timber-concrete composite floor structure. It is unique because the connections of both parts of the composite T-cross-section are assembled from non-metallic materials only. The connection element is a glued board made of plywood. Experimentally, by a shear test, values of secant slip modulus were determined at 12 samples in total. Results of shear tests were analysed by exploratory statistical methods. This method of connection has a medium level of rigidity when loaded with shear force and compared to other types of connection. However, at the same time it manifests a significant area of plastic deformations at higher levels of load. Part tests were carried out with 3 samples, each of which was subject to various levels of environmental effects and a load time before the test. Results were compared with results of the test performed with a reference sample – a non-composite structure of identical dimensions. Experimental data were compared with data provided by the theoretical design model as stated in Eurocodes. The comparison relates to short-term behaviour of the structure. This article also includes consideration of a comparison with the performance of the HBV® System type structure. With the part span of 6.5 m, the final maximum short-term resistance of the timber-concrete composite structure was approximately 200 kN and the maximum average mid-span deflection was approximately 54 mm. For a structure exposed for the period of 12 months to an outdoor environment with the load action for 166 days with the intensity of 10 kN/m2, the final short-term resistance of the timber-concrete composite structure was higher by 21% than that of a non-composite structure of identical dimensions. [ABSTRACT FROM AUTHOR]

This paper presents the experimental results of push-out tests on simple timber-concrete connection systems. The tested configurations concern the notch without rod, the rod without notch and the notch combined to rod. The rod is composed by common reinforcing steel bar threaded at their extremity and screwed in the timber beam. These fasteners are combined with rectangular or triangular notch connections between timber and concrete. These solutions are chosen because they are simple to apply in a timber-concrete composite structure using materials available in the local market. The mechanical properties such as the strength, the slip modulus and the failure mode of the tested specimens are obtained from the load-slip curves of the push-out tests. The comparisons are done to evaluate the differences and similarities between the various tested shear connections. The comparisons show the efficiency of the simple composite systems of connections tested using the reinforcing steel bars alone or combined with a notch connection in the timber beam. [ABSTRACT FROM AUTHOR]

• Glued inclined rebar as shear connector. • Association of glued inclined rebar and triangular notch as shear connector. • The use of contact surfaces with cohesive properties in numerical simulations. Shear connectors have a great influence on the mechanical behavior of timber-concrete composite structures, interfering with the stiffness and strength of the structural elements. This paper presents experimental and numerical studies about the mechanical behavior of timber-concrete composite structures by evaluating two types of connectors: one formed by an inclined rebar and another formed by the association of an inclined rebar with a triangular notch. The rebars used were ribbed-type with yield strength equal to 500 MPa, and their fixation on timber was made by gluing with epoxy resin. The experimental determination of the strength, the slip modulus and the failure modes were made by means of push-out tests. Subsequently, a numerical evaluation using ABAQUS was carried out in order to develop a three-dimensional numerical model that represented these types of connections, considering the nonlinearities of the materials, the orthotropy of timber and the interaction between the components. It was observed that the notch connection showed greater strength and stiffness when compared to the connection without notch. The comparison between the numerical and experimental results showed that the numerical model was able to predict, with good approximation, the failure load and the slip modulus of the connection without notch, while the stiffness of the numerical model proved to be higher than that observed in the experimental analysis for the notch connection. [ABSTRACT FROM AUTHOR]

Timber-concrete composite beams (TCCs) are made from a concrete topping fastened to a timber beam. Different methods can be used to construct the TCCs. The concrete topping can be either poured on the timber beam with preinstalled connectors or prefabricated off-site and then connected to the timber beam. The timber beam can be shored during assembling with the concrete topping or left unshored. The use of the shored construction is usually recommended as a way to reduce long-term deflection; however, it is costly. This paper investigates the influence of the construction method on the long-term behavior. A previously developed rigorous uniaxial finite element (FE) software has been first validated on some long-term tests performed in Sweden on TCCs with prefabricated concrete slabs and different connection systems. The FE model has then been used to carry out some analyses where the deflection in the long term has been compared with the same TCC constructed in different ways. Parameters investigated include the mode of construction of the concrete slab (prefabricated off-site or cast in situ), the assembly of the composite beam (with shored or unshored timber beam), the storage time of the concrete slab, and the time between the end of construction and the application of the live load. The outcomes of this numerical study indicate that by prefabricating the concrete slab it is possible to reduce the long-term deflection, particularly when the slab is stored for at least 28-56 days before it is connected to the timber beam and when the timber beam is shored for at least 1 day. In these cases, the effect of concrete shrinkage is reduced, as well as the instantaneous and delayed deflection due to the self-weight of the beam. Conversely, systems with concrete poured on the timber beam should be shored for a longer time (at least 7 days). Shoring the timber beam does not markedly change the increase in longterm deflection due to concrete shrinkage; however, it does raise the tensile stresses in the concrete slab during the period the shores are left in place, leading to the potential for cracking when stiff shear connectors are used and for long shoring times. [ABSTRACT FROM AUTHOR]

In this paper a statistical analysis was done, to assess the most adequate statistical distributions and corresponding parameters for the timber–concrete connection properties, aiming linear and non linear analysis. The properties considered for the linear analysis were the load–slip modulus and load carrying capacity. For the non-linear analysis five mathematical models were selected to describe the connection load–slip behavior. The models were fitted to the load–slip curves available in the references. The obtained parameters were subjected to a statistical analysis in order to assess the most adequate statistical distributions. On this analysis the whole set of suitable results available included more than 1000 single test results to have a sample as broad as possible. A chi-square goodness-of-fit with a 5% of significance level were performed to selected distributions, in most of the situations the normal distribution was found to be adequate. Furthermore, for most of the connection types good load–slip descriptions could be obtained with the 3 parameter models. [ABSTRACT FROM AUTHOR]

• Several kinds of assembled shear connectors were proposed for timber-concrete composite (TCC) beams. • Single-shear tests were conducted on the proposed shear connectors to evaluate the shear behaviour of the connectors. • The assembled shear connectors exhibited improveed load-slip behaviour compared to the shear connectors with single mechanical fasteners. • Finite element modelling was performed to predict the behaviour of the shear connectors. This paper presents three types of assembled shear connectors consisting of a steel component anchored to timber by screws and glued-in rods (GiRs) for timber-concrete composite (TCC) beams. Single-shear tests were carried out to evaluate the shear performance of the proposed shear connectors. The test results showed that the anchors bent obviously and finally failed in "single-hinge" and "double-hinge" yield modes under lateral load. The timber surrounding the anchors was obviously crushed, and cracks in concrete were also observed during testing. The shear connectors with I-shaped steel anchored by GiRs exhibited the highest shear capacity of 158.92 kN. The folded steel plate shear connectors with GiRs and screws showed the highest slip modulus (38.41 kN/mm), and the highest ductility with an average coefficient of 29.6, respectively. In general, the shear connectors anchored with GiRs showed better shear performance compared to the screwed shear connectors. Finally, numerical simulation results indicated that the simulated load–slip curves were generally in good agreement with the test curves. The anchor diameter and strength and the frictional coefficient between anchors and the wall of the holes in timber have significantly influenced the shear performance of the proposed shear connectors. [ABSTRACT FROM AUTHOR]

Design of modern timber floors is often governed by the vibration serviceability requirements. One way to improve vibration serviceability is through the design of two-way floor systems. In this paper, the behaviour of two-way LVL–concrete composite plates and a plate strip is investigated experimentally, with an emphasis on the performance of proposed dovetail joint for connecting the adjacent LVL panels. The investigations consist of the experimental modal analysis and static load deformation tests, performed under multiple support conditions. The results show a significant two-way action, indicated by about 45% higher fundamental natural frequency when four edges are supported instead of two. The point load deflection in the centre of the plate was reduced of about 9%. Furthermore, a numerical model for two-way TCC plates was developed and results show a wide agreement with the experimental behaviour, except for discrepancies related to deflections on the plate edge. The results from the experimental and numerical investigations indicate that the dovetail joint can produce a stiff connection, such that the LVL layer could be regarded as continuous in the connected direction. • Experimental investigations of two-way LVL–concrete composite floor plates with various support conditions. • Continuity between LVL panels provided by a novel dovetail joint. • Experiments include experimental modal analysis (EMA) and static deformations under concentrated loads. • Presented numerical model shows a wide agreement with the experimental results. • Effectivity of the dovetail joint and considerable two-action of the plates are identified. [ABSTRACT FROM AUTHOR]

The aim of this study is to analyze the mechanical behavior of timber-concrete connections established through glued notches, as well as the parameters that may affect it, specifically in the experimental shear test procedure. With these objectives in mind, a database based on a literature survey was created, identifying different shear test set-ups. In addition, a numerical approach was also adopted, based on experimental results. A numerical finite element method model was developed in order to describe the behavior of this type of connection. To validate the model, three sets of experimental tests were used, differing according to the notch material, the concrete class and the set-up's geometry. Using this model, parametric studies were developed to analyze the effects of the material and geometrical parameters and support conditions. The database showed that double-shear tests were the most common experimental test set-up. The numerical modeling allowed a good approximation to a connection's linear-elastic behavior. Parametric studies showed that the parameter with the greatest effect on a connection's stiffness was the modulus of elasticity of timber, in contrast with the support conditions. The locations chosen to measure displacements on timber and concrete elements were also shown to affect the calculated connection stiffness. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the outcomes of short-term collapse tests performed on eleven laminated veneer lumber (LVL)–concrete composite floor T-beams. Different variables such as span length (8 and 10 m), connection and concrete types, and design level (well- and under-designed, in terms of connector numbers) were investigated. During 4-point bending tests, mid-span deflection, connection slips and strains were measured. Connection types investigated include triangular and rectangular (150 mm and 300 mm long) notches cut in the timber and reinforced with a coach screw, and modified toothed metal plates pressed on the edge of the LVL joists. All of the beam specimens were designed using the effective bending stiffness or -method, in accordance with Annex B of Eurocode 5. The same method was used for an analytical–experimental comparison of the beam’s performance at ultimate (ULS) and serviceability (SLS) limit state. All well-designed beams provided more than 95% composite action even though there were relatively few connectors (e.g. six 300 mm long notches on the 8 m span beam). The ULS and SLS live load capacity of the beams was found to be approximately 90% of that of a fully composite beam. Correction factors providing a 15% increase for deflection and a 13% reduction of the effective bending stiffness are proposed for calculations using the transformed section method for all well-designed beams, i.e. beams designed using the -method according to Annex B of Eurocode 5. Although the -method was found to be significantly underestimate the ULS strength, it provided an accurate prediction of the short-term deflection. In terms of the connection type, the 300 mm rectangular notches provided the best performance, with high stiffness and strength beyond the ULS load level, and requiring fewer connectors along the beam. The triangular notch was found to be a viable alternative, with more connectors but was easier and faster to cut than a rectangular notch. Metal plate connectors provide a practical construction possibility, but the beam stiffness was found to rapidly deteriorate beyond the ULS load level. [Copyright &y& Elsevier]

This paper, presents 3D non-linear FEM models developed to predict the mechanical behaviour of timber–concrete joints made with dowel-type-fasteners. They consider isotropic behaviour for steel and concrete and orthotropic behaviour for timber, all the materials are modelled with non-linear mechanical behaviour. Besides, the interaction between materials is modelled using contact elements associated with friction. The results obtained in the numerical simulations are evaluated and compared with results obtained in laboratory shear tests. The model developed showed the capacity to simulate the behaviour of the joints if the materials used are properly modelled. Nevertheless further research is still necessary to improve the modelling of the materials particularly timber. [Copyright &y& Elsevier]

The paper presents the structural solution to the joisted floor when the timber joist of composite cross-section and the concrete slab are interconnected via a special semi-rigid connection and form a timber-concrete joisted floor composite element. Tensioned bottom flange is formed of a solid timber joist, the web is of oriented strand boards (OSB) and the compressive top flange is of a concrete slab into which a part of the web is let in. Studies were carried out on the "sleeved" connector in this part of the web between OSB and concrete slabs that should increase the stiffness of this connection. Theoretical and experimental researches on inter-behaviour of connection of the sub-components of composite timber I beam-concrete were carried out, the obtained results are presented and evaluated. [ABSTRACT FROM AUTHOR]

This paper presents a two-dimensional interface model for timber-concrete contacts, that has been developed based on the empirical observations from a set of friction tests and additional micromechanical assumptions. In tangential direction, the interface model accounts initial bonding and debonding between the surfaces, different static and kinetic friction as well as smooth transition between them, effects of load reversal, pressure-dependence in friction and sticking stiffness and slip softening over increasing cumulative slip. In normal direction, simple linear cohesive and pressure-overclosure behaviour is assumed. The model has been formulated in cohesive-frictional interface framework, coupling damage-based cohesive behaviour with elastoplasticity-based frictional behaviour. The model has been tested in various cases and verified by comparison on a set of 27 tests on timber-concrete contact pairs under cyclic loading with varying normal pressure and multiple different material pairs. The interface model is able to capture relevant parts of the experimentally observed tangential behaviour, indicating suitability to present timber-concrete interface behaviour under cyclic loading. [ABSTRACT FROM AUTHOR]

• Investigates initial bond and friction between timber and concrete under cyclic load. • Influence of wood product, grain orientation and surface treatment is analysed. • Interlocking effect due to matching surfaces is investigated. While friction plays an important role in many timber-concrete composite structures, it has been studied only to a limited extent and current knowledge is not comprehensive enough for rigorous modelling of e.g. timber-concrete connections. The purpose of this study is to fill part of this gap by investigating timber to concrete friction under cyclic loading experimentally. The tests were conducted with small-scale double-sided shear specimens. The materials included surface treated and untreated edge-faces of coniferous laminated veneer lumber and birch plywood combined with high-strength concrete grout that was cast directly on the timber parts. The initial shear strengths are evaluated by the Mohr-Coulomb criterion, and the static and kinetic friction coefficients are determined for each load cycle. Based on the results, influence of the cumulative displacement, the wood product, the grain orientations and the surface treatment on the initial shear strength and the friction coefficients are analysed. The tests also showed interlocking that is likely related to the matching surfaces created by prior de-bonding. As this interlocking affects the results, it was also investigated. [ABSTRACT FROM AUTHOR]