A geometrically defined stiffness contact for finite element models of wood joints

Finite element models tend to overestimate the actual elastic response of structural timber connections. The paper shows how such overprediction relates to the modelling of the contact between fasteners and timber. The use of a control parameter called stiffness contact is proposed. After an experimental campaign, a method to determine it, based only on the geometry of a rectangular contact area, is proposed. The modeling adequacy is demonstrated by applying it to dowel embedment and moment resistant wood joint tests. The obtained results show good agreement with the experimental test series

Comparación de las técnicas no destructivas de tomografía ultrasónica y resistencia a la perforación en la evaluación de discos de madera

El planteamiento de este trabajo surge de la necesidad de obtener una información fiable del estado de los árboles, en particular de aquellos que se encuentran en las ciudades. El arbolado urbano proporciona múltiples e importantes funciones, aportando beneficios ambientales, sociales y económicos. Puesto que su deterioro puede derivar en fatales accidentes para el ciudadano, este estudio llevado a cabo en discos de madera seleccionados de árboles que formaron parte del arbolado urbano de Campinas (São Paulo) puede colaborar con la propuesta de llevar a cabo acciones preventivas y eficaces para evitar estos posibles e importantes daños. Para ello se ha analizado la relación de dos de los ensayos no destructivos más empleados para determinar si un árbol presenta o no riesgo de caída, la propagación de ondas (tomografía ultrasónica) y la resistencia a la perforación, ambas actuando como complemento al análisis visual del árbol. Los resultados obtenidos ponen de manifiesto que la asociación de las dos técnicas ayuda a mejorar la precisión del diagnóstico del estado del árbol

Modelling of moment transmitting beam-to-column timber connections accounting for frictional transmission

The development of accurate structural modelling techniques is required to promote the use of timber as a renewable alternative to other structural materials. Due to their remarkable influence on the global behaviour of a timber structure, an accurate description of the performance of structural connections is needed. Particularly in the case of moment transmitting beam-to-column connections with dowel-type fasteners, such properties are difficult to obtain experimentally. This paper develops a finite element (FE) model that simulates the behaviour of these connections under quasi-static loading, with a focus on the estimation of rotational stiffness and load distribution among the dowels. The model is validated against short-term laboratory tests. Resulting friction between timber members due to the installation procedure must be considered, as it greatly influences the rotational response. Besides, non-linear behaviour of timber and a softened contact parameter have been implemented, and their influence on the FE model validation process is demonstrated

Modelling of moment transmitting beam-to-column timber connections accounting for frictional transmission

The development of accurate structural modelling techniques is required to promote the use of timber as a renewable alternative to other structural materials. Due to their remarkable influence on the global behaviour of a timber structure, an accurate description of the performance of structural connections is needed. Particularly in the case of moment transmitting beam-to-column connections with dowel-type fasteners, such properties are difficult to obtain experimentally. This paper develops a finite element (FE) model that simulates the behaviour of these connections under quasi-static loading, with a focus on the estimation of rotational stiffness and load distribution among the dowels. The model is validated against short-term laboratory tests. Resulting friction between timber members due to the installation procedure must be considered, as it greatly influences the rotational response. Besides, non-linear behaviour of timber and a softened contact parameter have been implemented, and their influence on the FE model validation process is demonstrated

A geometrically defined stiffness contact for finite element models of wood joints

Finite element models tend to overestimate the actual elastic response of structural timber connections. The paper shows how such overprediction relates to the modelling of the contact between fasteners and timber. The use of a control parameter called stiffness contact is proposed. After an experimental campaign, a method to determine it, based only on the geometry of a rectangular contact area, is proposed. The modeling adequacy is demonstrated by applying it to dowel embedment and moment resistant wood joint tests. The obtained results show good agreement with the experimental test series