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Numerical determination of the slip modulus of dowel-type timber joints
Abstract
Modeling timber joints it is essential to know the stiffness of the connections. In some cases the prescriptions of the standards contain only general approach without considering significant effects. The presented paper analyzes the load-slip behavior of dowel-type timber joints. A computer calculation method is presented, which is able to take into account the geometrical and stiffness parameters as well as the different joint arrangements.
... Based on the material and geometric properties of the connection, predictive models were mainly developed in the wooden connections field [32][33][34][35], while such models do not exist for timber-concrete connections. Researchers Heine and Dolan [36], Laszlo Erdodi [37], Dominguez [38], and Kobel [39] made outstanding contributions to the characterization of timber connections. They proposed numerical predictive models to determine the whole load-slip curve based on the European Yield Model (EYM), taking into account the non-linear behavior of the timber and the fastener (determined from experimental tests). ...
... Apart from the model proposed by Dias [28], which is descriptive, no model has been developed that predicts the load-slip relationship over the entire domain in timberconcrete connections based on the material and geometric characteristics of the connection. Therefore, those above-mentioned predictive numerical models [36][37][38][39] represent the basis for the formation of a new model. ...
... Apart from the model proposed by Dias [28], which is descriptive, no model has been developed that predicts the load-slip relationship over the entire domain in timber-concrete connections based on the material and geometric characteristics of the connection. Therefore, those above-mentioned predictive numerical models [36][37][38][39] represent the basis for the formation of a new model. ...
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.
... Out of the numerous workflow models the p-graphbased workflow model is suitable to generate optimal network structure with the methods of network synthesis while it is mathematically justified. The workflow constructed in this way can be well applied in the most various fields, for example Sergyán [3][4], Vámossy [1][2], Györök [7][8], Erdődi [5][6] and Bencsik [14]. In a previous paper [9] we have already presented the use of this model in other fields of profession. ...
Out of the workflow representations that are excellent to model business processes this paper examines the possibilities of the p-graph-based workflow modeling for administrative activities. Taking the special requirements of document management into account it gives a possible solution for document processing, the more reality like modeling of activities and resources. This paper introduces special descriptors for the various document types, activities and resources. Thus making the p-graph based workflow modeling more applicable for the modeling of administrative processes. Beyond the static examinations the extension of the p-graph-based model enables the analysis of dynamic behavior and the analysis of process executions.
An improved method tor calculating force distributions in moment-stiff metal dowel-type timber connections is presented, a method based on use of three-dimensional finite element simulations of timber connections subjected to moment action. The study that was carried out aimed at determining how the slip modulus varies with the angle between the direction of the dowel forces and the fibres in question, as well as how the onhotropic stiffness behaviour of the wood material affects the direction and the size of the forces. It was assumed that the force distribution generated by the moment action taking place strives to minimize the slip rotation between the separate members of a given timber connection. The results of modified hand calculations based on the finite clement calculations carried out were found to differ appreciably from the results of conventional hand calculations.
Timber joints are usually considered as perfectly pinned or stiff against rotation during the calculations of engineering timber structures. However the semi-rigid behavior the joints cannot be avoided in case of accurate calculations. In this paper the rotational stiffness and the full moment-rotational behavior of dowel-type timber joints were analyzed using computer algorithm validated by finite element analysis. Based on the numerical calculation and the experimental results the paper describes the influences of the joint geometry, the grain direction and the number and position of connectors on the moment-rotational behavior.
Failure of bolted timber joints is analyzed experimentally and numerically. In this study, the prediction of the load-carrying
capacity of dowel-type joints with one dowel under static loading is based on the analysis of fracture in wood contrarily
to most engineering methods that are based on the yield theory. Mechanical joints consist of glued laminated spruce members
and steel dowels. In the different analyzed tests, the bolt loads the wood parallel or perpendicular to the grain. The wood
member thickness is chosen sufficiently thin to avoid the fastener from presenting plastic hinges. The influences of different
structural parameters such as the dowel diameter, the edge- and end-distances are investigated. The fracture propagation analysis
is carried out with the Finite Element (FE) method in the framework of Linear Elastic Fracture Mechanics (LEFM). The only
identified parameter is the critical energy release rate in mode I (GIc). The comparison between experimental and numerical results shows that the fracture must be considered for a correct prediction
of the ultimate load and that LEFM can help to improve design codes.
This paper deals with several items concerning the restoration of historical wooden structures. Firstly general problems related to the identification of the material and of the whole structural complex are faced. They are mainly influenced by either wood defects and degradations or past technologies for construction. An overview of the possible upgrading intervention is also introduced. Therefore the paper has been focused on a study case of historical roofing structure. In particular the detailed geometrical and mechanical surveys are presented. The main aspects of the structural modeling are evidenced and the results of the structural analysis are discussed. On the bases of the structural behavior pointed out, the appropriate retrofitting intervention has been illustrated.
In this paper, the problem of the local resistance of wood beneath a bolt connector subjected to shear is studied both in the case of load parallel to the grain and perpendicular to the grain. Two specific test methods were adopted in order to study the influence of lateral confinement. Thin plate specimens of glued laminated wood pierced through by a steel bar (16 mm diameter) were considered to simulate a real situation. From the load-slip curves, the initial stiffness and the embedding strength of wood beneath the connector were estimated. Moreover, the geometric interferometry technique made it possible to obtain the entire field of displacements in the wood surrounding the bolt. Comparisons of test results with existing data are in good agreement for specimens without confinement. Confined specimens show a slight increase in bearing capacity for load parallel to the grain and a significant increase of the ultimate bearing capacity for load perpendicular to the grain. Negligible differences were noted in deformability.
Dowel type timber connections, strength modeling
- M U Pedersen
Design of timber structures Part 1-1, General, Common rules and rules for buildings
- Msz En