Serviceability performance studied covers three different performance attributes of a building. These attributes are 1) vibration of the whole building structure, 2) vibration of the floor system, typically in regards to motions in a localized area within the entire floor plate, and 3) sound insulation performance of the wall and floor assemblies. Serviceability performance of a building is important as it affects the comfort of its occupants and the functionality of sensitive equipment as well. Many physical factors influence these performances. Designers use various parameters to account for them in their designs and different criteria to manage these performances. Lack of data, knowledge and experience of sound and vibration performance of tall wood buildings is one of the issues related to design and construction of tall wood buildings.
In order to bridge the gaps in the data, knowledge, and experience of sound and vibration performance of tall wood buildings, FPInnovations conducted a three-phase performance testing on the Origine 13-storey CLT building of 40.9 m tall in Quebec city. It was the tallest wood building in Eastern Canada in 2017.
Three performance attributes of a building for serviceability performance are 1) vibration of the whole building structure, 2) vibration of the floor system, typically in regards to motions in a localized area within the entire floor plate, and 3) sound insulation performance of the wall and floor assemblies. Serviceability performance of a building is important as it affects the comfort of its occupants and the functionality of sensitive equipment as well. Many physical factors influence these performances. Designers use various parameters to account for them in their designs and different criteria to manage these performances.
The overall objectives of this stud were threefold:
1. The vibration performance tests were to experimentally determine the dynamic properties, e.g., natural frequencies (periods) and damping ratios of the WIDC building through ambient vibration testing on:
o the bare structure in 2014,
o the finished building upon completion of the construction with occupants in 2015, and
o the finished building after 3 years of service in 2017.
2. The floor vibration tests were to evaluate vibration performance of the innovative CLT floor based on the bare floor fundamental natural frequency, 1 kN static deflection, and subjective evaluation.
3. The sound transmission tests were to determine the Apparent Sound Transmision Class (ASTC) and Apparent Impact Insulation Class (AIIC) of selected innovative CLT floor assemblies.
This research paper deals with the evaluation of the dynamic modal vibration tests conducted on an innovative timber structure, the ETH House of Natural Resources. The building serves as a demonstrator of several innovative structural systems and technologies relating to timber. The main load-bearing structure comprises a posttensioned timber frame, which was subjected to modal vibration tests, firstly in the laboratory and, subsequently on the construction site. In this paper, the modal characteristics (eigenfrequencies, damping ratios and mode shapes), obtained from the laboratory testing campaign are presented. The modal vibration data is evaluated using polynomial and subspace identification techniques. The obtained results reveal that the structure exhibits pure translational, beam and column modes, as well as mixed beam-column modes. The bottom connection of the columns delivers significant influence on the modal characteristics, whereas the level of post-tensioning force yields no substantial influence in the modal characteristics obtained from low amplitude modal vibration tests.
International Conference on Structural Health Assessment of Timber Structures
September 9-11, 2015, Wroclaw, Poland
A timber building made of cross-laminated timber (CLT) panels is a modular system where all panels are pre-cut in factory. On site, the single components are then assembled connecting the panels with mechanical fasteners, mainly angle brackets with nails and/or screws, hold-downs, metal plates and self-tapping screws. CLT wall panels are very rigid in comparison to its connections. Thus, connections play an essential role in maintaining the integrity of the structure providing the necessary strength, stiffness and ductility, and consequently, they need close attention by designers. However, there is still a lack of proper design rules for these connections, in particular under cyclic loads, mainly due to a large variety of connectors and connection systems. In this paper, the different properties of connections for CLT buildings, on both monotonic and cyclic behaviour, are described using recent works from different authors. From the bibliography, it is clear that experimental data, regarding both monotonic and cyclic tests, is required for the assessment of the performance of the CLT structural system attending to the interaction between rigid panels and connections. This work evidences results from experimental campaigns and numerical analysis regarding definition and quantification of the cyclic response of CLT connections. Examples regarding monotonic and cyclic tests aimed to evaluate cyclic behaviour of connections through physical parameters, such as the impairment of strength and the damping ratio, are presented and discussed.
In the present work the change in natural frequencies, damping and mode shapes of a prefabricated timber floor element have been investigated when it was integrated into a building structure. The timber floor element was first subjected to modal testing in laboratory with ungrounded and simply supported boundary conditions, and then in situ at different stages of building construction. The first five natural frequencies, damping ratios and mode shapes of the floor element and the entire floor were extracted and analysed. It may be concluded that the major change in natural frequencies occur as the floor element is coupled to the adjacent elements and when partitions are built in the studied room, the largest effect is on those modes of vibration that largely are constrained in their movement. The in situ conditions have a great influence on the damping, which depends on the damping characteristics of the supports, but also on the fact that the floor is integrated into the building and interacts with it. There is a slight increase of damping in the floor over the different construction stages and the damping values seem to decrease with ascending mode order.