Recent research in the field of assessment of hygrothermal response has focused on either laboratory experimentation or modelling, but less work has been reported in which both aspects are combined. Such type of studies can potentially offer useful information regarding the benchmarking of models and related methods to assess hygrothermal performance of wall assemblies.
This report documents the experimental results of a benchmark experiment that was designed to allow benchmarking of stud drying predicted by NRC’s an advanced hygrothermal computer model called hygIRC, when subjected to nominally steady-state environmental conditions. hygIRC uses hygrothermal properties of materials derived from tests on small-scale specimens undertaken in the laboratory. The drying rates of wall assembly featuring wet studs that result from moisture accumulated during the framing stage of a 5 or 6 storey building. The drying rate of those studs was assessed in an experiment undertaken in a controlled laboratory setting. The results were subsequently used to help benchmark hygIRC reported under separate cover.
The objective of the task is to select, from the 679 locations in Table C-2 of the 2010 National Building Code of Canada (NBC 2010) , several representative locations for which long-term historical weather data exists. This information from these locations can subsequently be used to determine the exterior boundary conditions for input files for hygrothermal simulation programs and hygrothermal testing in the laboratory.
This report discusses the selection of locations for the hygrothermal simulation task of the project on Mid-rise Wood Buildings and the determination of spray-rates and pressure differentials for the water penetration testing portion of the project.
The present paper deals with the effect of moisture induced stresses (MIS) on the mechanical performance of a glulam beam of Vihantasalmi Bridge in Finland. MIS caused by high moisture gradients in a cross section of the glulam beam are calculated by a hygro-thermal multi-Fickian model for evaluation of moisture content, relative humidity and temperature in wood that is sequentially coupled with an orthotropic-viscoelasticmechanosorptive model for calculation of wood stresses. Both models, already developed in Abaqus FEM code by some of the authors in their previous works, had to be modified for the Nordic climate. The obtained levels of MIS are then compared to the Eurocode 5 design resistances. The study aims at providing suggestions to future developments of Eurocode 5 for the correct evaluation of the influence of moisture content on service life in timber bridge elements.
The objective of this study was to assess the potential effects of climate change on the moisture performance and durability of massive timber walls on the basis of results derived from hygrothermal simulations. One-dimensional simulations were run using DELPHIN 5.9.4 for 31 consecutive years of the 15 realizations of the modeled historical (1986–2016) and future (2062–2092) climates of five cities located across Canada. For all cities, water penetration in the wall assembly was assumed to be 1% wind-driven rain, and the air changes per hour in the drainage cavity was assumed to be 10. The mold growth index on the outer layer of the cross-laminated timber panel was used to compare the moisture performance for the historical and future periods. The simulation results showed that the risk of mold growth would increase in all the cities considered. However, the relative change varied from city to city. In the cities of Ottawa, Calgary and Winnipeg, the relative change in the mold growth index was higher than in the cities of Vancouver and St. John’s. For Vancouver and St. John’s, and under the assumptions used for these simulations, the risk was already higher under the historical period. This means that the mass timber walls in these two cities could not withstand a water penetration rate of 1% wind-driven rain, as used in the simulations, with a drainage cavity of 19 mm and an air changes per hour value of 10. Additional wall designs will be explored in respect to the moisture performance, and the results of these studies will be reported in a future publication. View Full-Text
Unlike other solid wood panel systems, ICLT panels are manufactured without the use of adhesives or fasteners. Wood members are connected with tongue-andgroove joints within a given layer and with dovetail joints across layers. This reduces cost and allows ICLT panels to be disassembled at end of life to be repurposed in the building material supply chain. In addition, ICLT panels provide a means to utilize lumber from trees killed by mountain pine beetle.
Durability is critical for sustainable construction, and avoidance of moisture accumulation in wood structural members is essential for long-term performance. Little work has been done specifically on hygrothermal performance of massive timber construction.
The objective of this research is to identify building envelope design and construction practices for robust hygrothermal performance of ICLT walls in multiple U.S. climates.
This report contains test results for the fire-retardant-treatment (FRT) and hygrothermal effects on structural glued laminated timber (glulam). This is the second part of the collaborative research project between ABA - The Engineered Wood Association, Tacoma, WA, and USDA Forest Products Laboratory (FPL), Madison, WI. The first part of this project is related to FRT laminated veneer lumber (LVL) and the results are provided in a separate research report.
Selected mechanical properties, including tension, bending, and shear of the FRT glulam treated with the American Wood Protection ASsociation (AWPA) P49 and P50 fire retardants were evaluated in this study. These results are used to support the development of an ASTM standard for FRT glulam.
Project contacts are Shiling Pei (Colorado School of Mines) and Samuel L. Zelinka (Forest Products Laboratory)
This project will generate three benchmark data sets for multistory CLT building moisture performance in different climate zones. Data will include moisture contents at key wood components and high moisture risk locations throughout the buildings. A relatively simple, but fully validated, numerical model for analyzing similar building moisture performance will be recommended. These results will be useful for structural engineers and architects to accurately consider moisture in their design of mass timber buildings.