IOP Conference Series: Earth and Environmental Science
According to the predictions of United Nations (2017) there are more than 7 billion people on Earth and this number will reach 9.7 billion by 2050. Today, most of the population lives in the urban areas and the rapid growth entails more construction in a housing sector. Since the industrial revolution the world has experienced countless technological attainments and on the other hand risky increase in natural resources use, energy consumption, greenhouse gases emission, ozone depletion, toxification and global temperature rising. The question how the cities can respond to urban growth is related to the sustainable goals of Agenda 2030. This research discusses potential of the usage of timber as construction material and it also brings the answer to this question. The wood is 100% renewable, recyclable and nontoxic material with capacity to absorb CO2 and perform low embodied energy. The increase of timber use in the construction contributes to sustainable development and to the reduction of waste, CO2 emission, as well as energy consumption. The aim of this paper is to discuss the advantages of using timber as a sustainable solution in urban context, in comparison with most commonly used concrete. The findings demonstrate the value of timber as sustainable construction material.
Relying on China’s national standard “Standard for Building Carbon Emission Calculation” and related reports published by the Athena Institute, this report calculates the life cycle carbon emissions of wood buildings in China. The study collects basic information of all the projects, such as quantity of building materials, building envelope, energy system and so on. Calculations are conducted for 7 projects from the aspects of product stage, transportation stage, construction stage, operational energy and demolition stage
Traditional wood-wood connections, widely used in the past, have been progressively replaced by steel fasteners and bonding processes in modern timber constructions. However, the emergence of digital fabrication and innovative engineered timber products have offered new design possibilities for wood-wood connections. The design-to-production workflow has evolved considerably over the last few decades, such that a large number of connections with various geometries can now be easily produced. These connections have become a cost-competitive alternative for the edgewise connection of thin timber panels. Several challenges remain in order to broaden the use of this specific joining technique into common timber construction practice: (1) prove the applicability at the building scale, (2) propose a standardized construction system, (3) develop a convenient calculation model for practice, and (4) investigate the mechanical behavior of wood-wood connections. The first building implementation of digitally produced through-tenon connections for a folded-plate structure is presented in this work. Specific computational tools for the design and manufacture of more than 300 different plates were efficiently applied in a multi-stakeholder project environment. Cross-laminated timber panels were investigated for the first time, and the potential of such connections was demonstrated for different engineered timber products. Moreover, this work demonstrated the feasibility of this construction system at the building scale. For a more resilient and locally distributed construction process, a standardized system using through-tenon connections and commonly available small panels was developed to reconstitute basic housing components. Based on a case-study with industry partners, the fabrication and assembly processes were validated with prototypes made of oriented strand board. Their structural performance was investigated by means of a numerical model and a comparison with glued and nailed assemblies. The results showed that through-tenon connections are a viable alternative to commonly used mechanical fasteners. So far, the structural analysis of such construction systems has been mainly achieved with complex finite element models, not in line with the simplicity of basic housing elements. A convenient calculation model for practice, which can capture the semi-rigid behavior of the connections and predict the effective bending stiffness, was thus introduced and subjected to large-scale bending tests. The proposed model was in good agreement with the experimental results, highlighting the importance of the connection behavior. The in-plane behavior of through-tenon connections for several timber panel materials was characterized through an experimental campaign to determine the load-carrying capacity and slip modulus required for calculation models. Based on the test results, existing guidelines were evaluated to safely apply these connections in structural elements while a finite element model was developed to approximate their performance. This work constitutes a firm basis for the optimization of design guidelines and the creation of an extensive database on digitally produced wood-wood connections. Finally, this thesis provides a convenient design framework for the newly developed standardized timber construction system and a solid foundation for research into digitally produced wood-wood connections.
International Conference on New Advances in Civil Engineering
IOP Conference Series: Materials Science and Engineering
Related to sustainability movement and minimizing the carbon footprint, timber structures are becoming more attractive. Wood, as main structural material, offers many benefits relate mostly to economic and ecological aspects, compared to other materials as steel or concrete. On the other hand, physical characteristics of wood complicate the usage of a timber for high-rise or large-span structures. It brings a new challenge for architects and engineers to deliver feasible solution for usability of timber, despite its features. One of the possible solutions could be implementation of CLT (Cross-Laminate Timber) panels in structural systems developed earlier for buildings made of prefabricated concrete slabs. SOM in cooperation with Oregon State University are currently testing composite slabs made of CLT and thin concrete layer reinforcing the wood and protecting it from fire. Although the system solution looks promising, and could bring the result, slabs limit using of the space in layout. On the other hand, frame structures would be much more efficient. This article comes up with an idea of modular frame structure, which could help to solve the problem. The scheme is based on "gridshell" type systems, where rods form a more efficient shell for dealing with stress forces.
The desire for sustainability has propelled innovation in structural engineering for much of the 21st century. Implement sustainable design without sacrificing the structural integrity of a building is important. The timber-concrete composite (TCC) floor system is an alternative floor system that offers superior sustainability and quick installation compared to other composite floors. TCC is comprised of a reinforced concrete slab connected to timber plate/beams by shear connectors that transfer the internal forces through the shear flow. To resist bending forces the reinforced concrete slab experiences the majority of compression stress and the timber plate/beam experience the majority of tension stress. Compared to an equivalent all-concrete section the TCC system has similar strength and stiffness as well as reduced weight.
Sustainability is now becoming a major concern in the modern construction industry. Despite being a major economic sector, the construction industry is causing adverse environmental impact. To this end, special attention should be paid to the selection of more "green" construction materials for structural applications. Therefore, a reasonable choice of construction materials can be made on the bases of acceptable structural performance, economic benefits, and sustainability. For instance, the use of composite beams made with traditional concrete and bio-based materials (such as timber and bamboo) is a valuable solution. Timber-Concrete Composite (TCC) beams have been used for decades in various structural applications such as new buildings, refurbishment of old timber structures, and bridges with several environmental benefits. Recently, different researchers proposed composite beams similar to TCC ones but based on engineered bamboo commonly named Bamboo-Concrete Composite (BCC) beams. This study presents comparison of the failure mode of the TCC and BCC beams udder fourpoint bending test. In particular, TCCs beams are compared with BCC ones considering similar shear connectors.
Ascent, a 25 story residential tower located in Milwaukee, WI (USA), will become the tallest timber building in the world upon completion. This paper discusses the project's structural system, permit process, groundbreaking project specific testing, and several of the challenges the team overcame, all of which open the door to future Mass Timber projects; particularly in the United States.