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.
37th Danubia Adria Symposium on Advances in Experimental Mechanics
Research Status
Complete
Series
Materials Today: Proceedings
Summary
This paper presents the results of an investigation of the dynamic response of a point-supported cross-laminated timber (CLT) slab without joists with a column grid of 5.0 × 5.0 m and overall dimensions of 16.0 × 11.0 × 0.2 m. The results are based on a detailed experimental modal analysis, identifying seven modes from the dynamic response of 651 measurement points, including natural frequencies, mode shapes and damping ratios. These modal parameters exhibit a time variance that is due to environmental influences during the measurement period of two days. As a result of this disturbance effect, the determined mode shapes have a non-negligible imaginary part, which is eliminated by correcting each of the 73 measurements individually. The findings presented provide in-depth insight into the dynamic behavior of the large-scale CLT structure with point supports realized with a novel steel connector.
To predict and, when needed to fulfil regularizations or other requirements, lower the impact sound transmission in light weight buildings prior to building, dynamically representative calculation models are needed. The material properties of commonly used building components have a documented spread in literature. Therefore, to validate the junction models, the dynamics of the actual assembly components have to be known. Here, the dynamic properties of a number of component candidates are measured using hammer excited vibrational tests. The spread of the properties of the components are hereby gained. Some of the components are selected to build up wooden assemblies which are evaluated first when they are screwed together and later when they are screwed and glued together. The focus is here on achieving representative finite element models of the junctions between the building parts composing the assemblies.
To predict and, when needed to fulfil regularizations or other requirements, lower the impact sound transmission in light weight buildings prior to building, dynamically representative calculation models are needed. The material properties of commonly used building components have a documented spread in literature. Therefore, to validate the junction models, the dynamics of the actual assembly components have to be known. Here, the dynamic properties of a number of component candidates are measured using hammer excited vibrational tests. The spread of the properties of the components are hereby gained. Some of the components are selected to build up wooden assemblies which are evaluated first when they are screwed together and later when they are screwed and glued together. The focus is here on achieving representative finite element models of the junctions between the building parts composing the assemblies.
The timber building industry is developing building systems for urban buildings with open architecture based on long span floor systems. Span length can be increased with constant cross section by combining stiff floor elements e.g. hollow-box floors with supports that provide high rotational stiffness. Detailed knowledge of the vibroacoustic behavior of such a system is not available and is needed to design buildings that fulfill the requirements in an economic and sustainable way. We set up a prototype and performed experimental investigations to identify the modal properties of such a system and to gain understanding of the sound radiation properties under impact excitation. The measurements were performed in an industrial hall using experimental modal analysis (EMA) and the Integral Transform method (ITM). The results highlight the limitation of standard acoustic laboratories and show the importance of using advance measurement methods to acquire reliable data. The size of the element and the boundary condition clearly affect the radiated sound power at low frequencies. Sound radiation can be efficiently reduced above 50 Hz by using traditional strategies such as gravel in the cavity of the floor elements. Additionally, insights about the ITM are presented, showing that symmetry cannot be exploited and that there is no requirement for a baffle when impact excitation is under investigation.
A new timber frame structural system consisting of continuous columns, prefabricated hollow box timber decks and beam-to-column moment-resisting connections is investigated. The hollow box timber decks allow long spans with competitive floor height and efficient material consumption. To achieve long spans, semi-rigid connections at the corners of deck elements are used to join the columns to the deck elements. In the present paper, experimental investigations of a semi-rigid moment-resisting connection and a mock-up frame assembly are presented. The semi-rigid connection consists of inclined screwed-in threaded rods and steel coupling parts, connected with friction bolts. Full-scale moment-resisting timber connections were tested under monotonic and cyclic loading to quantify rotational stiffness, energy dissipation and moment resistance. The mock-up frame assembly was tested under cyclic lateral loading and with experimental modal analysis. The lateral stiffness, energy dissipation, rotational stiffness of the connections and the eigen frequencies of the mock-up frame assembly were quantified based on the experimental tests in combination with a Finite Element model, i.e., the model was validated with experimental results from the rotational stiffness tests of the beam-to-column connections. Finally, the structural damping measured with experimental modal analysis was evaluated and compared with FE model using the material damping of timber parts and equivalent viscous damping of the moment-resisting connections.
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