Airborne sound insulation performance of wall assemblies is a critical aspect which is directly associated with the comfort level of the occupants, which in turn affects the market acceptance. In single-family and low-rise residential buildings, the partition walls, whether loadbearing or non-loadbearing, are commonly framed with studs of solid sawn lumber of 2x4, 2x6, and 2x8. In commercial buildings and multi-storey residential buildings, the partition walls are commonly framed using light-gauge steel studs.
The shortcomings of solid sawn lumber studs form the motivation for this project to develop wood studs that would address these shortcomings to promote greater wood use in partition walls.
The conceptual design and fabrication work and the preliminary test results have shown that are partition-wall stud made out of composite wood material could have the same or better airborne sound insulation performance as compared to the 25 gauge steel stud. The concept is promising, with a manufacturing process and fabrication that would work and be practical.
This report addresses serviceability issues of tall wood buildings focusing on vibration and sound insulation performance. The sound insulation and vibration performance may not affect building's safety, but affects occupants' comfort and proper operation of the buildings and the funciton of sensitive equipment, consequently the acceptance of midrise and tall wood buildings in market place. 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.
This report addresses serviceability issues of tall wood buildings focusing on their vibration and sound insulation performance. The sound insulation and vibration performance may not affect the building’s safety, but affects the occupants’ comfort and the proper operation of the buildings and the function of sensitive equipment, consequently the acceptance of the midrise and tall wood buildings in market place. 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.
The measured and estimated values should also be correlated with actual experiences of the occupants in the building if such information is obtained, for example, through a survey.
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.
For wood floor systems, their vibration performance is significantly dependent on the conditions of their supports, specifically the rigidity of the support. Detrimental effects could result if the floor supports do not have sufficient rigidity. This is special ture for floor supporting beams. The problem of vibrating floor due to flexible supporting beams can be solved through proper design of the supporting beams. However, there is currently no criterion set for the minimum requirement for floor supporting beam stiffness to ensure the beam is rigid enough. Designers’ current practice is to use the uniform load deflection criteria specified in the code for designing the supporting beams. This criterion is based on certain ratios of the floor span (e.g. L/360, L/480 etc.). The disadvantage of this approach is that it allows larger deflections for longer-span beams than for shorter beams. This means that engineers have to use their experience and judgement to select a proper ratio, particularly for the long-span beams. Therefore, a better vibration-controlled design criterion for supporting beams is needed.
It is recommended to further verify the ruggedness of the proposed stiffness criterion for floor supporting beams using new field supporting beam data whenever they become available.
Wood-concrete composite slab floors provide a promising solution for achieving long spans and shallow wood-based floor systems for large and tall wood buildings. In comparison with conventional wood floor systems, such long span and heavy floors have a lower fundamental natural frequency, which challenges the floor vibration controlled design. A laboratory study, including subjective evaluation and measurement of the natural frequencies and one-kN static deflections, was conducted on wood-concrete composite floors. Method of calculation of the composite bending stiffness of the wood-concrete composite floor is proposed. The design criterion for human comfort was derived from the subjective evaluation results using the calculated fundamental natural frequency and 1 kN static deflection of one meter wide strip of the composite floor. The equation to directly determine the vibration controlled spans from the stiffness and mass was derived. Limited verification was performed. Further verification is needed when more field wood-concrete composite floors become available.
Mass timber is a generic name for a broad range of thick and heavy wood products such as cross-laminated timber (CLT), dowel-laminated timber (DLT), nail-laminated timber (NLT), and gluelaminated timber (GLT), among others. So far, vibration-controlled design methods have been developed mostly for CLT floors.
La construction massive en bois est un terme générique qui englobe une grande variété de produits du bois épais et lourds, notamment le bois lamellé-croisé (CLT), le bois lamellé-goujonné (DLT), le bois lamellé-cloué et le bois lamellé-collé (GLT). À ce jour, les méthodes de conception à vibrations contrôlées ont surtout été élaborées pour les planchers en CLT.
Mass timber (MT) building systems are gaining momentum around the world, especially in Canada where Federal and Provincial governments encourage the greater use of wood in construction projects through various promotion programs such as GCWood Program. In the meanwhile, seismic design provisions in the 2020 National Building Code of Canada have been revised, resulting in significantly higher seismic loads for structures in many locations. Consequently, there is a need to develop new lateral load resisting systems that allow mass timber structures to better compete against their counterparts in steel, concrete and masonry. Building on the success of midply shear walls for wood-frame construction, a multi-year research project was initiated at FPInnovaitons to develop MT version of midply shear wall systems that have greater structural capacities, fire, and acoustical performance.
In the first year of this project, literature reviews were conducted to identify the code requirements on MT components and to survey the available LLRSs used in the MTstructures. Conceptual MT midply wall systems meeting structural, fire, and acoustical performance requirements were proposed. An advisory group meeting was held to evaluate the practicability of the proposed MT midply systems. In the next fiscal year, the proposed MT Midply will be optimised further according to the comments and suggestions from the advisory group. Analytical evaluation of the proposed MT Midply wall systems along with necessary tests will be conducted. Based on the evaluation, a go / no-go decision will be made as to whether the study should be continued for the proposed MT Midply.
FPInnovations’involvement in various codes and standards technical committees aims to monitor, contributeor propose changes for improvement as well as to create new standards to include new wood products and systems based on knowledge developed from FPInnovations’ research activities. Involvement also allows FPInnovations to be aware of any potential changes to codes and standards and to recognize and address threats and opportunities for wood use. Codes and standards exist to protect consumers but are written to reflect the current practices and knowledge based on a consensus agreement by committee members. FPInnovations’ involvement in codes and standards committees helps to align the coming changes with new wood products. This InfoNote reports on FPInnovations’ contribution to the floor vibration-control design methods on codes and standards implementation and research.