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Kleinheubach, Germany

Kasal B.,Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut | Kasal B.,TU Braunschweig | Guindos P.,Fraunhofer Wilhelm KlauditzInstitut | Polocoser T.,TU Braunschweig | And 3 more authors.
Journal of Performance of Constructed Facilities | Year: 2014

This article presents the seismic performance of a timber frame with three-dimensional (3D) rigid connections. The connections were made with self-tapping screws and hardwood blocks were used to support the beams. The frame was designed to resist high seismic excitations with the goal of controlling the drift. The moment-rotation characteristics of the connections were measured in the laboratory by applying static cyclic loads. The frame made of laminated wood beams and columns, and cross-laminated lumber deck, was subjected to seismic, white noise, snapback, and sinusoidal sweep excitations. The synthetic seismic excitation was designed to contain a considerable amount of energy close to the frame's first natural frequency. The structure showed no significant damage up to a peak ground acceleration of 1.25g. Failure of the frame occurred due to shearing of the columns with a peak ground acceleration of 1.5g. The designed structure fulfilled with current serviceability limits up to 0.8g. © 2014 American Society of Civil Engineers. Source

Haller P.,TU Dresden | Heiduschke A.,HESS Timber GmbH and Co. KG | Putzger R.,TU Dresden | Hartig J.,TU Dresden
Bautechnik | Year: 2015

Glued laminated timber girders were investigated, which were strengthened with compressed laminated wood at the tension lamella and optionally also at the compression lamella to increase load-bearing capacity and stiffness. Compressed laminated wood is a wood composite consisting of beech (Fagus sylvatica) veneers, which are impregnated with phenol-resorcin resin. Compressed laminated wood possesses a YOUNG's modulus of more than 20 000 N/mm2 and a bending strength of more than 200 N/mm2, which is compared to glued laminated timber GL24h a doubling and a tripling, respectively. The strengthening of the GL24h girders with compressed laminated wood led to a doubling of the bending capacity and to an increase of stiffness of about one third compared to plain GL24h girders with the same cross section. Moreover, the joint of glued laminated timber and compressed laminated wood was exposed to wetting-drying cycles to investigate the durability. Partly impregnated compressed laminated wood absorbed a lot of moisture and swelled heavily, but still less than plain beech wood. Thus, this material is only recommendable for the service classes 1 and 2. Completely impregnated compressed laminated wood showed only very low moisture uptake and swelling and can be applied also in service class 3. © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG. Source

This article deals with calculative investigations on a novel connection concept for trussed girders in engineered timber structures. The forces between struts and ties are transferred by casted concrete blocks. The presented investigations include three-dimensional finite element models for determining stress distributions at the joints. Based on the results of the numerical model a simple strut-and-tie-model is developed for determining the internal forces and the deformation behavior of respective trussed girders. This provides a simple tool for the engineer to design such structures. The necessary static verifications are summarized in a design concept. © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

In this contribution, a novel connection system for engineered timber structures is presented. The objectives of the investigations were the significant improvement of the load-bearing behavior, the serviceability, the cost-effectiveness and the esthetic appearance of timber trussed girders. For this purpose, joints with high load-bearing capacity were developed. The innovative joint applies and combines advantages of various joint types like traditional carpentry, profiled shear planes used in timber-concrete hybrid-structures and casted tension anchors used in steel-concrete hybrid-structures. The efficiency of this novel concept results from the combination of these joint types as well as the stress-related application of the materials timber, steel and concrete. The forces between the struts are transferred primarily by form fit with casted concrete joints. The results of experimental investigations confirm the efficiency of these joints and the potential for application in various strut-and-tie systems. Copyright © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

Hartig J.,TU Dresden | Heiduschke A.,HESS Timber GmbH and Co. KG | Haller P.,TU Dresden
WCTE 2014 - World Conference on Timber Engineering, Proceedings | Year: 2014

This paper presents a novel jointing system for timber trussed girders where the rods to be joint are connected by casted concrete after assembling on the construction site. Therefore, an excavation is placed in the chord where all connecting rods end inside. Chords and compression rods are made of timber. For the tension rods, steel bars with anchor plates are applied. Thus, the concrete block is loaded in multiaxial compression. Due to casting of the concrete all parts of the joint are accurately fitting and almost no slippage occurs, which leads to very low deformations of the structure. Source

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