The increasing appetite for innovation, performance and sustainability in the Canadian Architecture, Engineering, Construction, Owners and Operators (AECOO) community is leading to the development and deployment of approaches, be they tools, technologies, practices, etc., that are causing a significant shift in the delivery and management of built assets. When deployed...
Cross-laminated timber has conquered new markets since the publication of volume I Basic design and engineering principles according to Eurocode. The present volume II describing Applications provides the designer of timber structures on the one hand with basics for design factors, mechanical properties and modelling with finite element method. On the other hand it describes in detail the design of floors, ribbed plates and walls e.g. by design approaches regarding forces in joints of plates and diaphragms, concentrated loads, openings, effective width and compression perpendicular to grain. Current scientific knowledge as well as experience from practical engineers is taken into account. 15 examples demonstrate the design approaches as references for practitioners. Closing background information for the shear correction coefficient, deformations due to concentrated loads and the modelling of crosslaminated timber as general grillage will illuminate the background and facilitate deeper understanding of the design with cross-laminated timber.
Project contact is Pierre Blanchet at Université Laval
The use of Building Information Modeling (BIM) models is not yet standardized. This situation limits the scope of the tool and this is particularly the case for systems not defined in the libraries of major BIM software. This results in a loss of productivity because each stakeholder will redefine materials and/or systems to a level of information corresponding to his own needs. This project aims, with the help of a research professional, to develop a BIM library that can contain the main information related to materials and systems to fully cover the needs of all users of the BIM model. This library will be made available to the public and will facilitate the use of wood systems by stakeholders.
The current study uses knowledge from digital architecture, computer science, engineering informatics, and structural engineering to formulate an algorithmic framework for integrated Computer-Aided Design (CAD) and Computer-Aided Engineering (CAE) of Integrally-Attached Timber Plate (IATP) structures. The algorithm is designed to take the CAD 3D geometry of an IATP structure as input and automates the construction and analysis of the corresponding CAE model using a macroscopic element, which is an alternative to continuum Finite Element (FE) models. Each component of the macro model is assigned a unique tag that is linked to the relevant geometric and structural parameters. The CAE model integrity is maintained through the use of the common data model (CDM) concept and object-oriented programming. The relevant algorithms are implemented in Rhinoceros 3D using RhinoCommon, a .NET software development kit. Once the CAE macro model is generated, it is introduced to the OpenSees computational platform for structural analysis. The algorithmic framework is demonstrated using two case structures: a prefabricated timber beam with standard geometry and a free-form timber plate arch. The results are verified with measurements from physical experiments and FE models, where the time needed to convert thousands of CAD assemblies to the corresponding CAE models for response simulation is considerably reduced.
Cross-laminated timber (CLT) is a type of mass timber panel used in floor, wall, and roof assemblies. An important consideration in design and construction of timber buildings is moisture durability. This study characterized the hygrothermal performance of CLT panels with laboratory measurements at multiple scales, field measurements, and modeling. The CLT panels consisted of five layers, four with spruce-pine-fir lumber and one with Douglas-fir lumber. Laboratory characterization involved measurements on small specimens that included material from only one or two layers and large specimens that included all five layers of the CLT panel. Water absorption was measured with panel specimens partially immersed in water, and a new method was developed where panels were exposed to ponded water on the top surface. This configuration gave a higher rate of water uptake than the partial immersion test. The rate of drying was much slower when the wetted surface was covered with an impermeable membrane. Measured hygrothermal properties were implemented in a one-dimensional transient hygrothermal model. Simulation of water uptake indicated that vapor diffusion had a significant contribution in parallel with liquid transport. A simple approximation for liquid transport coefficients, with identical coefficients for suction and redistribution, was adequate for simulating panel-scale wetting and drying. Finally, hygrothermal simulation of a CLT roof assembly that had been monitored in a companion field study showed agreement in most cases within the sensor uncertainty. Although the hygrothermal properties are particular to the wood species and CLT panels investigated here, the modeling approach is broadly applicable.
This paper presents the modeling of coupling effect of tension and shear loading on Cross Laminated Timber (CLT) connections using a finite element based algorithm called HYST. The model idealizes the connections as a “Pseudo Nail” - elastoplastic beam elements (the nail) surrounded by compression-only spring elements (steel sheath and wood embedment). A gap size factor and an unloading stiffness degradation index of the spring elements under cyclic loading were integrated into the optimized HYST algorithm to consider the coupling effect. The model was calibrated to compare with 32 configurations of CLT angle bracket and hold-down connections tests: in tension with co-existent constant shear force, and in shear with co-existent tension force. The results showed that the proposed model can fully capture the coupling effect of typical CLT connections, considering strength degradation, unloading and reloading stiffness degradation, and pinching effect. The model provided a useful tool for nailbased timber connections and a mechanism-based explanation to understand the hysteretic behaviour of CLT connections under bi-axial loading.
Project contact is Christian Dagenais at Université Laval
The use of materials in a building is traditionally determined from its combustibility (via ULC S114 or ULC S135) and by its flame propagation index (via ULC S102). The ULC S102 Flame Spread Test, developed in 1943, has historically reduced risk through its method of classifying materials. However, this test does not provide quantitative information on the combustion properties of materials, such as heat flow. The latter is one of the most important variables in the development of a fire. Thus, a new approach would be preferable in order to review the classification of materials according to ULC S102 and ULC S135 (cone calorimeter). The objective of this project is to develop a new approach to classifying materials based on cone calorimeter test results. These results can subsequently be used in numerical modeling as part of a fire safety engineering design. A significant amount of cone calorimeter (ULC S135) testing of materials currently evaluated according to ULC S102 will be required.
International Conference on Structures and Architecture
Structures and Architecture: Beyond their Limits
Proceedings of the Third International Conference on Structures and Architecture (ICSA2016), July 27-29, 2016, Guimaraes, Portugal
In the last twenty years CLT (cross-laminated timber) panels have become quite widely employed to build multi-storey buildings often characterized by the presence of many internal and perimeter shear walls. Building superstructures in which beam-and-column frameworks resits effects of gravity loads and core substructures and exterior CLT shear walls resist effects of lateral forces have been found structurally effective. Advantages of such structural arrangements can include creation of large interior spaces, high structural efficiency, and material economies. Here the behaviour of multi-storey buildings braced with CLT cores and additional CLT shear walls is examined based on numerical analyses. Two procedures for calibrating numerical analysis models are proposed and discussed here. The first approach is to use information from Eurocode 5, and the second approach is to use specifically applicable experimental data obrained through laboratory studies. Technically different ways of connecting CLT panels in order to obtain suitably stiff horizontal diaphragms are also presented.