Forests can help mitigate climate change in different ways, such as by storing carbon in forest ecosystems, and by producing a renewable supply of material and energy products. We analyse the climate implications of different scenarios for forestry, bioenergy and wood construction. We consider three main forestry scenarios for Kronoberg County in Sweden, over a 201-year period. The Business-as-usual scenario mirrors today's forestry while in the Production scenario the forest productivity is increased by 40% through more intensive forestry. In the Set-aside scenario 50% of forest land is set-aside for conservation. The Production scenario results in less net carbon dioxide emissions and cumulative radiative forcing compared to the other scenarios, after an initial period of 30–35 years during which the Set-aside scenario has less emissions. In the end of the analysed period, the Production scenario yields strong emission reductions, about ten times greater than the initial reduction in the Set-aside scenario. Also, the Set-aside scenario has higher emissions than Business-as-usual after about 80 years. Increasing the harvest level of slash and stumps results in climate benefits, due to replacement of more fossil fuel. Greatest emission reduction is achieved when biomass replaces coal, and when modular timber buildings are used. In the long run, active forestry with high harvest and efficient utilisation of biomass for replacement of carbon-intensive non-wood products and fuels provides significant climate mitigation, in contrast to setting aside forest land to store more carbon in the forest and reduce the harvest of biomass.
The two primary considerations for construction project management are budget and time management. Modular construction has the potential to improve construction productivity by minimizing time and costs while improving safety and quality. Cross-Laminated Timber (CLT) panels are beneficial for modular construction due to the high level of prefabrication, adequate dimensional stability, and good mechanical performance that they provide. Accordingly, CLT modular construction can be a feasible way to speed up the construction and provide affordable housing. However, an in-depth study is needed to streamline the logistics of CLT modular construction supply chain management. CLT modular construction can be performed by two primary means based on type of modules produced: panelized (2D) and volumetric (3D). This research aims to help the Architecture, Engineering, and Construction (AEC) industry by developing a tool to assess the impact of various logistical factors on both panelized and volumetric modular construction productivity. Discrete-Event Simulation (DES) models were developed for panelized and volumetric CLT modular construction based on a hypothetical case study and using data collected from superintendents and project managers. Sensitivity analysis is conducted using the developed models to explore the impact of selected manufacturing and logistical parameters on overall construction efficiency. Comparing volumetric and panelized simulations with the same number of off-site crews revealed that the volumetric model has lower on-site process duration while the off-site process is significantly longer. Accordingly, from manufacturing to the final module assembly, the total time for the volumetric model is longer than panelized model. Moreover, the simulations showed that volumetric modular construction is associated with less personnel cost since the main process is performed off-site, which has lower labor costs and a smaller number of crews required on-site. This framework could be used to identify the optimum construction process for reducing the time and cost of the project and aid in decision-making regarding the scale of modularity to be employed for project.
Project contact is Cristiano Loss at the University of British Columbia
This research aims at developing novel multi-material deconstructable hybrid connections for mass timber prefabricated buildings. Connections will be conceived in order to (i) meet multi-objective structural performance, (ii) favour modular construction, (iii) favour quick erection of buildings, (iv) quick disassemble and possible reuse of the timber members, and (v) provide seismic-resistant structural assemblies.
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.
An innovative concept for a modular timber concrete composite system for short span highway bridges has been designed and key components experimentally validated. The proposed system consists of a Ultra-High Performance Fibre Reinforced Concrete(UHPFRC) deck and glue-laminated timer (glulam) girders linked to act compositely together by reinforcing steel bar shear connectors. This composite system has light, stable modules that can be rapidly constructed on site with less special equipment. Simple design checks indicate that the concept satisfies all serviceability limit state(SLS) and ultimate limit state(ULS) requirements of the Canadian Highway Bridge Design Code. Pull-out tests characterized the embedment lengths of 20M steel bar connectors to be 10 bar-diameters in UHPFRC. Push-off tests determined the embedment lengths of the same bars to be 30 bar-diameters glued into the timber girders. The slip modulus of the connectors is determined to be 67 kN/mm. The stiffness of the crosswise self-tapping screw connectors were tested and found to be structurally insignificant in this application. The excellent tensile and cracking properties of the reinforced UHPFRC deck was experimentally verified. A small amount of reinforcement would further improve the ductility of the UPHFRC deck system.