In Phase I (2018-19) of this project on Prefabricated Heavy Timber Modular Construction, three major types of connections used in a stackable modular building were studied: intramodule connection, inter-module vertical connection, and inter-module horizontal connection. The load requirement and major design criteria were identified...
Previous studies have mainly focused on the behaviour of timber under uniformly distributed compression perpendicular to the grain (CPG) loads. However, there are many practical applications in which timber is loaded by non-uniformly distributed CPG loads. Different design and test codes like the Eurocode 5 (EC5), DIN 1052:2004, ASTM D143- 94 and EN-408:2010 only account for load configurations where timber is subjected to uniformly distributed loads. For specific uniformly distributed load (UDL) configurations the bearing capacity of timber (solid softwood timber or Glulam) in compression is adapted by using a load configuration factor (kc,90) according to EC5, the European code for design of timber structures. EC5 has no guidelines for cross-laminated timber (CLT) under UDL with the exception of the Austrian National Regulations for EC5.
In this work, an experimental and numerical study on the bearing capacity and displacement behaviour of CLT subjected to non-uniformly distributed loading (NuDL) is conducted on eight different load configurations. A steel-CLT connection in which the CLT is partially loaded is used in this study. Finite element modelling, performed using the commercial software Abaqus CAE is used as the numerical simulation of the experimental study and is validated by experimental results. Load configuration factors (kc,90) from experimental results are compared with values from the Swedish CLT handbook (KL-Trähandbok). The outcome of the study shows that load configuration factor for NuDL cases is higher than for UDL cases. Hence, for same load configurations a lower CPG strength is required in NuDL than in UDL. Moreover, numerical results feature overall good congruence with the elastic phase of the experiments and have the potential to augment experiments in further understanding other complex steel-CLT connections
Mass timber and CLT construction offers many advantages, such as enhanced modularity, reduced construction schedules, improved thermal performance, and material sustainability. However, mass timber’s propensity to absorb moisture from the environment and the relative vapor impermeability of CLT panels introduces unique challenges when incorporated with the building enclosure. These challenges should be considered during design and construction phases to ensure long-term performance.
The VaproShield Mass Timber Building Enclosure Design Guideline covers the best practices for the design and construction of high-performance CLT wall and roof assemblies. RDH is the principal author and editor of the guide and within its capacity, we do not purport to endorse any specific material or technical matter within this guide.
Advancement in engineered wood products altered the existing building height limitations and enhanced wooden structural members that are available on the market. These coupled with the need for a sustainable and green solution to address the ever-growing urbanization demand, avails wood as possible candidate for primary structural material in the construction industry. To this end, several researches carried out in the past decade to come up with sound structural solutions using a timber based structural system. Green and Karsh (2012) introduced the FFTT system; Tesfamariam et al. (2015) developed force-based design guideline for steel infilled with CLT shear walls, and SOM (2013) introduced the concrete jointed mass timber hybrid structural concepts. In this research, the basic structural concepts proposed by SOM (2013) is adopted. The objective of this research is to develop a wind and earthquake design guideline for concrete jointed tall mass timber buildings in scope from 10- to 40-storey office or residential buildings. The specific objective of this research is as follow:
Wind serviceability design guideline for hybrid mass-timber structures.
Calibration of design wind load factors for the serviceability wind design of hybrid tall mass timber structures.
Guidelines to perform probabilistic modeling, reliability assessment, and wind load factor calibration.
Overstrength related modification factor Ro and ductility related modification factor Rd for future implementation in the NBCC.
Force-based design guideline following the capacity based design principles.
This study illustrates the range of possible wood construction approaches for school buildings that are up to four storeys in height. As land values continue to rise, particularly in higher-density urban environments, schools with smaller footprints will become increasingly more necessary to satisfy enrollment demands. There are currently a number of planned new school projects throughout British Columbia that anticipate requiring either three-or four-storey buildings, and it is forecasted that the demand for school buildings of this size will continue to rise.
This study is closely related to the report Risk Analysis and Alternative Solution for Three- and Four-Storey Schools of Mass Timber and/or Wood-Frame Construction prepared by GHL Consultants, which explores the building code related considerations of wood construction for school buildings that are up to four storeys in height. Though wood construction offers a viable structural material option for these buildings, the British Columbia Building Code (BCBC 2018) currently limits schools comprised of wood construction to a maximum of two storeys, while also imposing limits on the overall floor area. As such, the reader is referred to the GHL report for further information regarding building code compliance (with a particular emphasis on fire protection) for wood school buildings.
The costs of mass timber may be higher, but the added premium on their prices make them economically feasible. Beyond the economics, mass timber structures present a unique opportunity to develop and test the resiliency of the owner organization and its capacity to innovate. A collective effort to strengthen the supply chain in Ontario (especially the manufacturing stage) is one of the key tools to reduce costs. Having a dedicated fire consulting firm and the early engagement of regulatory bodies and consecrators are some of the key means to control risks in this domain. Earlier projects relied on covering/insulating mass timber sections to achieve the required fire requirements. Increasingly, charring is becoming an acceptable means for fire protection. Using Integrated Project Delivery system (IPD) and Building Information Modeling (BIM) can provide the contractual and technical platforms to boost coordination and promote collaborative design and construction.