Project contact is Jianhui Zhou at the University of Northern British Columbia
Summary
Building acoustics has been identified as one of the key subjects for the success of mass timber in the multi-storey building markets. The project will investigate the acoustical performance of mass timber panels produced in British Columbia. The apparent sound transmission class (ASTC) and impact insulation class (AIIC) of bare mass timber elements as wall and/ or floor elements will be measured through a lab mock-up. It is expected that a database of the sound insulation performance of British Columbia mass timber products will be developed with guidance on optimal acoustical treatments to achieve different levels of performance.
This Report presents the results from experimental studies of the airborne sound transmission of mass timber assemblies, together with an explanation of the calculation procedures to predict the apparent sound transmission class (ASTC) rating between adjacent spaces in a building constructed of mass timber assemblies.
The experimental data which is the foundation for this Report includes the laboratory measured sound transmission loss of wall and floor assemblies constructed of Cross Laminated Timber (CLT), Nail-Laminated Timber (NLT) and Dowel-Laminated Timber (DLT), and the laboratory measured vibration reduction index between assemblies of junctions between CLT assemblies. The presentation of the measured data is combined with the presentation of the appropriate calculation procedures to determine the ASTC rating in buildings comprised of such assemblies along with numerous worked examples.
Several types of CLT constructions are commercially available in Canada, but this study focused on CLT assemblies with an adhesive applied between the faces of the timber elements in adjacent layers, but no adhesive bonding between the adjacent timber elements within a given layer. These CLT assemblies could be called “Face-Laminated CLT Assemblies” but are simply referred to as CLT assemblies in this Report. Another form of CLT assemblies does have adhesive applied between the faces of the timber elements in adjacent layers as well as adhesive to bond the adjacent timber elements within a given layer. These assemblies are referred to as “Fully-Bonded CLT Assemblies” in this Report. Because fully-bonded CLT assemblies have different properties than face-laminated CLT assemblies, the sound transmission data and predictions in this Report do not apply to fully-bonded CLT assemblies.
In many mass timber buildings, CLT or nail laminated timber (NLT) floors are designed with a concrete topping to improve acoustic separation, reduce vibration or act as a fire barrier. Little research has examined the fire behavior of these floor systems, but some preliminary tests involving LVL show that they may be able to meet three-hour fire resistance ratings, which could potentially open up the use of mass timber in Type I buildings, representing a large market opportunity. This project will test the behavior of composite floors under fire loading conditions considering the following parameters: shear connector type, mass timber panel types and thicknesses and concrete thicknesses. It will also test and validate an innovative fire research methodology using radiant panels.
Facilitation of Acoustics Testing for Sustainable Mass Timber Technologies, Leading to Publication of Open Source Acoustics Data for Standard Acoustics Scenarios
Project contact is Kevin Van Den Wymelenberg at the University of Oregon
Summary
Our aim is to support the acceptance and increase market share of sustainable mass timber construction technologies such as Cross Laminated Timber (CLT), Mass Plywood Panel (MPP), Glue Laminated Timber (GLT), and Nail Laminated Timber (NLT), by lowering or eliminating barriers due to lack of acoustics data for mass timber construction assemblies. Currently, sustainable mass timber projects carry the cost of required acoustics testing, impairing their economic feasibility. With our new acoustics testing facility, testing supported by this grant will produce common acoustics data on the assemblies most in market demand. These data will be hosted in an online open-access database, supporting rapid growth in this industry. Increasingly specialized testing scenarios will be more easily accommodated, as this facility is located closer to USFS source materials and production facilities than currently operating facilities and is designed specifically for the specialized requirements of testing mass timber assemblies. Since sustainable mass timber technologies allow increased utilization of lower quality timber, and timber with insect damage, increasing the market share of mass timber will increase utilization of USFS timber, specifically that which might otherwise remain on-site unused. With removal of this type of timber, fire load will be lessened as well. Initial testing supported by this grant will include mass timber assemblies constructed with lower quality and smaller dimension timber.
Overall moisture management during construction has become increasingly important due to the increase in building height and area, which potentially prolongs the exposure to inclement weather, and the overall increase in speed of construction, which may not allow adequate time for drying to occur. This report provides guidelines and relevant information about on-site moisture management practices that can be adapted to suit a range of wood construction projects...
Project contact is Shiling Pei at the Colorado School of Mines
Summary
Nail and Dowel Laminated Timber (NLT and DLT) are efficient technologies to build mass timber floor systems directly out of dimension lumber. It is relatively inexpensive to construct and has substantial potential to help expand the mass timber building market, particularly when the floor spans mainly in one direction. There have been multiple NLT projects constructed in the seismic region, which represents a large portion of the CLT construction market. The lateral design of NLT/DLT floor systems is currently based on very conservative assumptions (essentially equating its performance to a traditional joist-sheathing light-frame wood floor system) due to this lack of validated performance examples. This project will systematically demonstrate the potential of NLT/DLT floor systems under extreme lateral loads through component level testing and full-scale building level shake table tests. Through collaboration with manufacturers and designers (StructureCraft and Magnusson Klemencic Associates (MKA)), several full-sized NLT/DLT floor will be tested to failure in the structural engineering laboratory at Colorado State University. Based on component level test results, 2 or 3 floors of NLT/DLT diaphragms will be incorporated into a (planned) full-scale 10-story full-scale mass timber building that will be tested on the world’s largest outdoor shake table for demonstration and education/outreach.
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