Cross Laminated Timber (CLT)

This report provides an overview of cross laminated timber (CLT) in the construction industry. It discusses the manufacturing process, benefits, performance, and limitations of CLT.

Running head: CROSS LAMINATED TIMBER
Cross Laminated Timber (CLT)
Name of the Student
Name of the University

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Table of Contents
Introduction......................................................................................................................................3
Concept of CLT...............................................................................................................................3
Manufacturing process.....................................................................................................................4
Benefits of CLT...............................................................................................................................4
Performance of CLT........................................................................................................................5
Limitations of CLT..........................................................................................................................6
Conclusion.......................................................................................................................................7
References........................................................................................................................................8

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Introduction
Traditional timber structures are utilized as lightweight framework systems with linear
solid-wood elements. Concrete and steel have become more readily available in 20th century.
Therefore, timber was replaced by steel and concrete as it has been cost effective. Later on, the
focus on timber get increased in mid 1960s by the introduction of novel wood based product
known as engineered wood product (EWP). Products including glued laminated timber (GLT)
helps in enabling construction of more complex structures. This report focuses on the cross
laminated timber (CLT) utilization in construction industry.
Concept of CLT
CLT constitute of a plate-like engineered timber product that can be optimized for
bearing loads in and out of plane. CLT include an uneven number of layers, each of side-by-side
placed that are arranged crosswise to each other at an angle 90 degree. Timber coming into the
plant is normally furnace dried to a standard dampness substance of 12% +/ - 3% (Brandner et al.
2016). The wood as a rule touches base at the factory having just been dried to this particular.
The equivalent is the situation for evaluating. In Austria, it isn't exceptional for the feedstock to
have just been arranged by size or potentially grade upon entry. This is because of the utilization
of visual evaluating for auxiliary and quality appropriateness of the wood at the sawmill
(Muszyński et al. 2019)). In spite of the fact that, evaluating for appearance reasons for existing
is regularly performed dependent on an organization's standard at the CLT fabricating plant.
In Europe, the visual evaluating necessities are that parallel layers must be at any rate
grade 2, yet opposite layers can be grade 3 (Flatscher and Schickhofer 2015). Stress evaluating is
the auxiliary choice of reviewing this timber and is done as per measures created by the

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individual nations. For instance, the United States should meet evaluation necessities as per
ANSI/APA PRG 320: Standard for Performance-Rated Cross-Laminated Timber (APA 2012).
The generation procedure is like that of compressed wood. The principle contrast is in the
dimensional qualities of the feedstock. The procedure of finger jointing and cutting the wood to
acquire the ideal lengths for layer development is the initial phase in the real get together of the
board.
Manufacturing process
The following sections show all relevant steps and process parameters are discussed.
Customary timber structures have been used as lightweight structure frameworks with straight
strong wood components. Cement and steel have turned out to be all the more promptly
accessible in twentieth century. In this way, timber was supplanted by steel and concrete as it has
been savvy. Later on, the attention on timber get expanded in mid 1960s by the presentation of
novel wood based item known as built wood item (EWP) (Liao et al. 2017). Items including
stuck covered timber (GLT) helps in empowering development of progressively mind boggling
and powerful direct bigger range structures.
Benefits of CLT
CLT gives the chance to a ceaseless structure envelope with a speedy erection time and a
fundamentally diminished development impression when contrasted with cement and steel
development. The boards can be utilized for the whole structure (for example floor, dividers, and
rooftop). The improvement time is abbreviated since the boards are produced to a plan of a pre-
assembled strong structure. Now and again, the structure time for a multistory structure can short
of what multi week per level (Leskovar et al. 2019). Since the boards can be gathered in such a

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brief timeframe, the structure is rapidly weatherproof and before long prepared to be used. A
case of a CLT building development procedure can be found in Figure 7.
Further advantages of CLT as a structure material incorporate less on location squander, a
lower interest for gifted development work and less interruption to encompassing neighbors.
Further, groups can be as meager as 2 to 8 craftsmen in addition to a couple of portable crane
administrators (Davids et al. 2017). In this manner, a lower capital expense and a quicker
undertaking fulfillment time give CLT further worthwhile advantages over the utilization of
cement and steel.
Performance of CLT
The performance of CLT has been broadly verified to give comparable or far superior
outcomes than cement and steel. Issues, for example, seismic execution, sound and warm
protection, life span, and flame assurance assume appropriate jobs in the permission of CLT as a
substantial development material particularly for structures bigger than single family homes.
Following are the aftereffects of CLT execution as a development material. The seismic
exhibition of CLT has been tried by establishments, for example, IVALSA (Trees and Timber
Research Institute of Italy) (Pozza et al. 2016). FP Innovations detailed their discoveries on the
tried 3-and 7-story structures tried in Japan. The structures were exposed to tremor movements at
a size of 7.2 with increasing velocities of 0.8 to 1.2 g (Crielaard et al. 2019). The 7-story building
was found to have no remaining distortion toward the finish of the test. Estimations were taken
on between story float and most extreme parallel twisting at the highest point of the structure.
The separate qualities were 40 mm (1.3%) and 287 mm.

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Sound protection can be a troublesome undertaking with any structure material. In the
United States, structures must be developed appropriately to guarantee they meet the
International Building Code (IBC) when required. FP Innovations led investigate on the subject
of sound protection and have discovered that with legitimate structure and establishment CLT
structures can accomplish sound protection levels which satisfy or surpass IBC guidelines and
give tasteful conditions to future inhabitants (Sikora, McPolin and Harte 2016).
Limitations of CLT
CLT as a structure material carries limits. The adaptability of CLT as a structure
framework is because of the adjustment in capacities as the thickness of the boards change. For
instance, with a 230 mm, 7-handle floor, CLT can give ranges of 7.5 m without bars or sections
(Thi et al. 2018). With the expansion of concrete as a fortification, the range can increment to 10
m without help pillars. The consolidation of shafts and brackets can expand the range to more
than 20 meters or more. CLT gives the chance to a ceaseless structure envelope with a speedy
erection time and a fundamentally diminished development impression when contrasted with
cement and steel development. The boards can be utilized for the whole structure.
Concerning the vertical heading, TRADA: Timber Research and Development
Association has planned a CLT building which achieves 12-stories. Following this, it appears
that the joining of steel or cement must be utilized in the plan to help higher structures. With this
expansion, structures generally made out of CLT material can attainably achieve dimensions of
30+ stories. As referenced previously, modeler Michael Green is growing such a structure with
insignificant consolidation of steel and concrete (Crielaard et al. 2019).
Conclusion

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It can be concluded that the use of CLT has been creating a revolutionary change on the
construction industry. This report has discussed about overview of cross laminated timber. The
manufacturing process of the CLT in construction industry. The benefits of the CLT in
construction industry has been discussed. The performance of CLT has been explained properly
in the report. The limitations of the CLT has been analyzed in the report.

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References
Brandner, R., Flatscher, G., Ringhofer, A., Schickhofer, G. and Thiel, A., 2016. Cross laminated
timber (CLT): overview and development. European Journal of Wood and Wood
Products, 74(3), pp.331-351.
Crielaard, R., van de Kuilen, J.W., Terwel, K., Ravenshorst, G. and Steenbakkers, P., 2019. Self-
extinguishment of cross-laminated timber. Fire Safety Journal.
Davids, W.G., Willey, N., Lopez-Anido, R., Shaler, S., Gardner, D., Edgar, R. and Tajvidi, M.,
2017. Structural performance of hybrid SPFs-LSL cross-laminated timber panels. Construction
and Building Materials, 149, pp.156-163.
Flatscher, G. and Schickhofer, G., 2015. Shaking-table test of a cross-laminated timber
structure. Proceedings of the Institution of Civil Engineers-Structures and Buildings, 168(11),
pp.878-888.
Leskovar, V.Ž., Žigart, M., Premrov, M. and Lukman, R.K., 2019. Comparative assessment of
shape related cross-laminated timber building typologies focusing on environmental
performance. Journal of Cleaner Production, 216, pp.482-494.
Liao, Y., Tu, D., Zhou, J., Zhou, H., Yun, H., Gu, J. and Hu, C., 2017. Feasibility of
manufacturing cross-laminated timber using fast-grown small diameter eucalyptus
lumbers. Construction and Building Materials, 132, pp.508-515.
Muszyński, L., Gupta, R., hyun Hong, S., Osborn, N. and Pickett, B., 2019. Fire resistance of
unprotected cross-laminated timber (CLT) floor assemblies produced in the USA. Fire Safety
Journal.

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Pozza, L., Scotta, R., Trutalli, D., Polastri, A. and Smith, I., 2016. Experimentally based q-factor
estimation of cross-laminated timber walls. Proceedings of the Institution of Civil Engineers-
Structures and Buildings, 169(7), pp.492-507.
Sikora, K.S., McPolin, D.O. and Harte, A.M., 2016. Effects of the thickness of cross-laminated
timber (CLT) panels made from Irish Sitka spruce on mechanical performance in bending and
shear. Construction and Building Materials, 116, pp.141-150.
Thi, V.D., Khelifa, M., Oudjene, M., El Ganaoui, M. and Rogaume, Y., 2018. Numerical
simulation of fire integrity resistance of full-scale gypsum-faced cross-laminated timber
wall. International Journal of Thermal Sciences, 132, pp.96-103.