Introduction
Wood is an essential construction material that galvanizes every state-of-the-art used in a constructed structure (Yan 2011). Wood is a powerful construction substance that can be important in designing, modifying, and restructuring modern structures. A timber material that seems always forgotten and its capability doubted is the Cross-Laminated Timber (CLT), which is an engineered timber that has gained considerable fame in Canada, North America, and the United States (Yan 2011). The solid, perfectly prefabricated, and the engineered wood panel is capable of making enormous buildings including skyscrapers as it ensures the rigidity and stability required for human activities (Harris 2012). Although its perfection in the construction industry is an unprecedented success, the use of cross-laminated timber in construction continues to be a subject of public and engineering discourses. About such issues, this essay seeks to present a literature and artifacts review about cross-laminated timber and its use in the construction of wooden skyscrapers.
Structural issues associated with CLT: Resilience and Stability
When Architect Michael Green ventured into the idea of creating cross-laminated timber and suggested several significances about the newly engineered wood material, people thought it was a useless idea (Gagnon & Pirvu 2011). One of the disturbing factors that continually causes discourses among the engineers is the resilience and stability of the wooden skyscrapers constructed from the cross-laminated timber. Many remarkable houses ranging from residential buildings to commercial buildings have established that cross-laminated timber has several advantages that it can offer to the global construction realm. According to Mohammad, Gagnon, Douglas, and Podesto (2009), cross-laminated timber is an efficient construction material because of its dimensional stability that allows for the construction of long floor slabs that are wide and constructible in single flats that have long walls. From the perspective of a wooden skyscraper, this characteristic makes the wooden flats highly rigid and structurally stable. This innovation is actually unimaginable in the construction world.
Despite its resilience and stability in ensuring that, buildings are serving residential and commercial purposes; a growing concern is associated with the concept of stability that the multi-layer wooden panels can offer (Schmidt & Griffin 2009). Although the cross lamination innovation provides the dimensional and structural ability in all directions of a building due to the availability of the strong fasteners that come from that traditionally and modernly designed techniques, the strength and the lifetime resilience of the towers made from the cross-laminated timber is doubtable (Lam & Haukaas 2010). From an engineering perspective and from the established scientific facts from the forestry departments, wood is generally an easily decaying structural material that rarely offers any optimal resilience to either a commercial or a residential building (Schmidt & Griffin 2009). This worry has gone beyond the public and the people who are venturing into the real estate business, where the safety of the residential clients’ matters. Most criticizers of the cross-laminated timber innovation state that wood is normally an impoverished structural material.
Structural issues associated with CLT: Heat and Thermal Performance
One of the factors that construction engineers often seek to answer in the construction of residential and commercial buildings is the relevance of the structural materials in the heat reduction and temperature regulation aspects. Of course, residents and people acquiring spaces for commercial purposes often look for accommodations with well-regulated heat and temperatures. Compared to the concrete skyscrapers, which normally radiate a lot of heat during the summer seasons, the cross-laminated wood technology has a high thermal performance, thus, it reduces the cooling and heating expenses incurred by the occupants. In the North America and Europe, the most common innovative connection systems used to reinforce the towers are “the wall to foundations, wall-to-wall intersections, and wall to floor/roof intersections” (Mohammad, Gagnon, Douglas, & Podesto 2009, p.7). With these elegant design techniques, the cooling and heating of the buildings are perfect. Such a good thermal performance makes the CLT towers imperative in the above regions.
What worries people and engineers most is the flammability of the CLT wooden skyscrapers. The CLT wooden skyscrapers may face the implications of proving efficient in protecting millions of occupiers during the tragic events of fire. The CLT wooden material is highly flammable and any tragic event from fire may cause millions of deaths in the residential and commercial buildings. Another factor that continues to disturb the CLT tower engineers is the ability of the wooden skyscrapers to maintain a longtime dump resistance. According to Crespell and Gagnon (2010), the cross-laminated timber has a low damping ratio estimated at 1% in dampness, which makes the timber weak in resisting dampness. Therefore, the duration and longtime sustainability of the skyscrapers made from the cross-laminated timber may remain limited by its weakness associated with the dampness factor. The CLT towers may not serve the long-term residential and commercial purposes of the occupiers.
Structural issues associated with CLT: Vibrations and earth tremors
People fear the tragic collapse of concrete skyscrapers that cause serious deaths and fatalities that happen due to the impact from the solid rocks and the hard-concreted materials that cause bruises on the human flesh and crushes on the bones. When Michael Green thought of the CLT innovation, the idea that crossed his mind was how the CLT structures would enhance rigidity that would protect the occupants from the impact of the earth’s tremors and vibrations. When engineers construct skyscrapers with the CLTs, they imagine the ability of the wooden skyscrapers to withstand the shock and vibration that comes from the earth’s tremors and earthquakes (Schmidt & Griffin 2009). In a 2009 engineering study about the durability of the CLT conducted by the Trees and Timber Research Institute of Italy (IVALSA), using three and seven tower types of CLT building designs exposed on a 7.2 magnitude Japanese Kobe earthquake, the CLT towers demonstrated a high resilience against the tremors.
The factual research of the IVALSA organization may not be sufficient to convince the worried timber engineers and residents who still doubt the stability and resilience of the CLTs against the seismic problems (Schmidt & Griffin 2009). The innovation of the cross-laminated timber will provide cheap construction solutions because the construction labor required on the site is minimal compared to the one needed at the concrete towers. However, this cost-effectiveness may not be important given the inability of the skyscrapers to resist the high-intensity earth tremors that exceed the magnitude of seven on an earthquake testing scale (Schmidt & Griffin 2009). Furthermore, studies have still established that the cost of the CLT material used in building a structure is about 15 percent lower than concrete, masonry, and steel mid-rise housing structures. The CLT building cost can save up to 50 percent compared to the concrete structures, but the costs of reconstructions after breakages are high.
Commercial issues associated with CLT: Cost Effectiveness
In most construction cases, CLT skyscrapers can live up to the structural conditions for these modern building designs. Several projects all over the world have already demonstrated the capabilities of CLT. Although the cost of constructing the wooden skyscrapers is relatively cheaper when compared to concrete skyscrapers, when it comes to the financial drawbacks of building skyscrapers using CLT, a number of issues spring up. Fire is among the biggest concerns for all structures made of wood. CLT panels are often thicker than the majority of the conventional wood panels (Van de Kuilen, Ceccotti, Xia, He, & Li 2010). However, the CLT panels are combustible and may be vulnerable to fire under certain situations. Even though CLT shows greater resistance to the effects of fire when compared to concrete and steel structures, CLTs could bring devastating consequences to the skyscrapers in case of fires. Fire and other tragic events cause reconstructions that deem more expensive.
The CLT materials are still more expensive than the concrete materials. The material cost of CLT slabs is about two times more costly than the pre-stressed concrete unfilled floor slabs. This leads to higher costs when constructing wooden skyscrapers compared to traditional skyscrapers made of concrete and steel. Other drawbacks of CLT in the construction of skyscrapers include inflexibility as all design matters have to be determined before fabrication, long-term stability/movement requires early consideration, and high environmental degradation potential (Van de Kuilen, Ceccotti, Xia, & He 2011). Enough damage has already happened to the world’s forests already and if this new CLT wood technology is to apply on a large-scale basis, the results can be devastating from the environmental perspective. The remaining forests would be under a serious threat of deforestation (Van de Kuilen, Ceccotti, Xia, & He 2011). Thus, although this technology comes with some benefits that may look appealing, a closer look at the accompanying cons makes it not that much attractive.
Due to the ease of manufacturing large-scale CLT panels, technicians now possess a new tool that can conquer the drawbacks usually encountered when applying single timber components (Trusty 2003). By applying high-quality, wooden connection methods combined with the systematically created CLT panels, house designers and structural engineers nowadays enjoy increased liberty in their constructional design methods and techniques. Distant from the technical merits accrued in the structural designs, the CLT panels can be valuable in a more cost-effective way when exposed to an industrial situation. In turn, this translates to walls and floor panels produced using a high degree of thorough prefabrication (Van de Kuilen, Ceccotti, Xia, He, & Li 2010). Thorough prefabrication normally helps in lowering the costs of materials and the time required for construction. In terms of use, CLT is useful in a wide range of circumstances. It can be useful in making state-of-the-art windows and doors.
Conclusion
CLT is an acronym that describes the cross-laminated timbers that come from small timber units, superbly engineered into big structural panels that are often stable, light, and rigid. Cross-laminated timber has become a faster and greener option when compared to concrete and steel structural frames. These panels come in various sizes and are effective in constructing entire structures, including skyscrapers. However, CLTs have their pros and cons (Trusty 2003). Perhaps the cross-laminated timber technology is one of the most fascinating building innovations that have spurred new construction innovations in the North American and European regions. Even though the superbly engineered wood material can perform effectively in the building of the wooden towers, the ability of the CLT innovations to provide any meaningful innovation in large skyscrapers is still miniature. CLTs still need to undergo several refurbishments and scientific tests to become the most important construction innovations in the contemporary world.
Reference List
Crespell, P, & Gagnon, S 2010, ‘Cross-laminated timber: A primer’, FP Innovations, vol. 4, no. 1, pp. 1-10.
Gagnon, S & Pirvu, C 2011, ‘CLT handbook: cross-laminated timber. FP Innovations, vol. 3, no. 1, pp. 1-6.
Harris, M 2012, ‘Wood goes high-rise’, Engineering & Technology, vol. 7, no. 9, pp. 43-45.
Lam, F & Haukaas, T 2010, ‘Innovative CLT Building Systems–Localized Rolling Shear Reinforcement’, The Transformation Journal, vol. 10, no. 3, pp. 1-6.
Mohammad, M, Gagnon, S, Douglas, B & Podesto, L 2009, ‘Introduction to Cross Laminated Timber’, Wood Design Focus, vol. 22, no. 2, pp. 3-12.
Schmidt, J & Griffin, C 2009, ‘Barriers to the design and use of cross-laminated timber structures in high-rise multi-family housing in the United States’, Journal of construction engineering, vol. 5, no. 2, pp. 3-9.
Trusty, W 2003, Sustainable Building: A Materials Perspective, Web.
Van de Kuilen, J, Ceccotti, A, Xia, Z, & He, M 2011, ‘Very tall wooden buildings with cross laminated timber’, Procedia Engineering, vol. 14, no. 1, pp. 1621-1628.
Van de Kuilen, J, Ceccotti, A, Xia, Z, He, M, & Li, S 2010, ‘Wood-concrete skyscrapers’, World Configuration on Timber Engineering, vol. 1, no, 3, pp. 1-13.
Yan, B 2011, ‘The Research of Economic Evaluation Method for Green Building’, Applied Mechanics and Materials, vol. 71, no. 2, pp. 211-215.