Building owners often state requirements that new buildings shall have open and flexible architecture in order to allow flexible use and future changes. A way to improve timber buildings in that direction is to increase the stiffness of the connections between horizontal and vertical members of the structural systems. This paper presents some numerical and analytical considerations with respect to the stiffness requirements for moment resisting timber connections. It also presents experimental tests and results for a moment resisting connection with inclined threaded rods installed in predrilled holes.
Long threaded rods have recently been widely used as a reinforcement of glued laminated timber in perpendicular to the grain direction. The recent research has thus focused mainly on the withdrawal properties of the threaded rods in the axial direction. Utilizing their large withdrawal stiffness and strength, the threaded rods can also effectively be used as connectors in moment resisting timber joints. Yet, in joints, the threaded rods are often imposed to a non-axial loading, due to inclination of the rod axis to the grain as well as loading direction different from the rod axis. No design models are currently available for the combined axial and lateral loading of the threaded rods. In the present work, the effects of the rod-to-grain and load-to-rod angles on capacity and stiffness of the threaded rods are investigated by use of experiments and finite element models. Based on those, analytical expressions for determining stiffness and capacity of axially and laterally loaded threaded rods are proposed, intended as a basis for practical joint design. Furthermore, effect of various boundary conditions applied at the rod-ends is studied.
Understanding the inherent damping mechanisms of floor vibrations has become a matter of increasing importance following the development of new composite floor layouts and increased span. The present study focuses on the evaluation of material damping in timber beam specimens with dimensions that are typical of common timber floor structures. Using the impact test method, 11 solid wood beams and 11 glulam beams made out of Norway Spruce (Picea abies) were subjected to flexural vibrations. The tests involved different spans and orientations. A total of 420 material damping evaluations were performed, and the results are presented as mean values for each configuration along with important statistical indicators to quantify their reliability. The consistency of the experimental method was validated with respect to repeatability and reproducibility. General trends found an increasing damping ratio for higher modes, shorter spans, and edgewise orientations. It is concluded from the results that material damping of timber beams of structural dimensions is governed by shear deformation, which can be expressed more conveniently with respect to the specific mode shape and its derivatives.
“Treet” is a 14-storey timber apartment building in Norway currently under construction. Ground works started in April 2014, and the residents can move in autumn of 2015. The building will be one of the tallest timber buildings in the world. The building consists of load-carrying glulam trusses and two intermediate strengthened levels. Prefabricated building modules are stacked on top of the concrete garage and on top of the strengthened levels. There is CLT in the elevator shaft, internal walls and balconies. But, CLT is not a part of the main load bearing system. Glass and metal sheeting protect the structural timber from rain and sun. The paper presents the design of the building as well as many of the investigations, considerations and discussions which took place during the design process. Finally some of the design verifications are presented.
“Treet” is a 14-storey timber apartment building in Norway currently under construction. Ground works started in April 2014, and the residents can move in autumn of 2015. The building will be one of the tallest timber buildings in the world. The building consists of load-carrying glulam trusses and two intermediate strengthened levels. Prefabricated building modules are stacked on top of the concrete garage and on top of the strengthened levels. There is CLT in the elevator shaft, internal walls and balconies. But, CLT is not a part of the main load bearing system. Glass and metal sheeting protect the structural timber from rain and sun.
This paper deals with the comfort properties in a planned 14-storey timber apartment building in Bergen, Norway. The building will be one of the tallest timber buildings in the world. The building consists of load-carrying glulam trusses with two intermediate strengthened levels. The truss carries prefabricated building modules. Herein, the evaluation with respect to dynamic behaviour of the building is described with emphasis on the horizontal acceleration due to wind forces.
"Treet" is a relatively high building with low structural weight. Its natural frequencies lie in the domain where wind can cause annoying motions or nausea. The stiffness and mass properties for glulam and concrete are well known, but poorly described for complex, complete building modules. To get better knowledge of dynamic behaviour of the prefabricated building modules, testing was needed. Based on the structural design and the module testing a FEM analysis model was generated in order to calculate the building's natural frequencies and modal mass. These parameters were used to determine the windinduced accelerations of "Treet".
Connections consisting of axially loaded connectors embedded in timber elements can be a strong and competitive alternative to dowel-type connections. Such connections combine high capacity and stiffness. However, especially in the case of screwed-in threaded rods, the up-to date theoretical models and available experimental results are limited. In this paper, a general theoretical model that predicts the withdrawal capacity and stiffness of connections with axially loaded connectors is presented. The model is validated with an experimental study of withdrawal of threaded rods from glulam elements.