Steel over timber

A comparison between steel and timber structures is be done on the bases of   structural performance and cost effectiveness. Structural performance involves the durability; sustainability and fire resistance of the structures build from these materials. These are the main reasons for choosing either of the materials in the construction houses, house frames and other major constructions such as bridges. However, the combination of most of these factors makes the steel structures to be preferred over timber. Steelwork in construction of major structures is on the rise because the builders are becoming more attuned to the advantages associated with steel structures (International Conference on Advances in Steel Structures,et. al  2002). The versatility of steel as a building material affords the architects and constructors to achieve the best structural designs as compared to timber structures.  

To begin steel has a high strength to weight ratio than wood and its dead weight is moderately small. The ductility of enables the steel to undergo big plastic deformation before it fails thus offering a large strength reserve, an important feature that makes it possible for steel structures to resist shock loading like earthquakes or blasts. This also makes steel structures to be more durable than the wooden ones due to extra strength (Case, Chilver, & Ross, 1999). The durability of timber structures is lower since timber has properties that cannot protect it from the harsh weather. Moreover, when steel structures are coated with paints, corrosion is reduced greatly while timber is affected by termites which make it very weak. The strength in steal can also be explained in terms of higher limit of yield strength. The steal material can be extending to a great length before strain hardening occurs (Yadav & Garg, 2015). The stiffness of the steel structures when subjected to a lot of tension is very high which makes it a priority in the constructions of large projects such as bridges (Parke, Nigel, & Institution of Civil Engineers, 2008).  

Comparing material strength (Parke, Nigel, & Institution of Civil Engineers, 2008)

material	Elastic modulus	Strength	properties
Timber	E long=1 kN/mm2 E trans=10 kN/mm2	Fc=12 N/mm2 Ft=10 N/mm2	Shrinkage lower elastic modulus over period of time
Steel	E=200kN/mm2	Fy= 250-450N/mm2 Same compression and tension	range of compression and fatigue may affect tensile range by buckling

 

In addition, the performance of steel in vibration in most building structures is very high.  The systems of steel construction normally meet the desired criteria for vibration performance without having to be modified .For applications that are more sensitive to vibration such as floors of operating theatres, the advantages of steel are normally captured after additional stiffening is applied to the steel frames. This in case there is a need for the steel frame to meet the criteria for acceptability. Even after the additional stiffening has been added to the frames, steel remain to be the best solution due to its light weight and cost effectiveness (Case, Chilver, & Ross, 1999). Thus, steel performs better in the construction of such structures as compared to timber that cannot withstand as much compression and tension. Timber has lower limits of yield strength which means that timber structures cannot withstand too much compression as compared to steel structures. The fragility of timber is higher as compared to the fabricated steel which means that steel would be preferred over timber in the construction of massive structures that are required to hold much weight (Muttoni, 2011).

Steel is a better material than timber when it comes to residential constructions and their designs. Among the many opportunities provided by steel is the ability afforded to builders where they can span larger distances when using ceiling joists of steel that those that are wooden. This allows the builders to have expanded options so that they can create new spaces while using the building products made of steel (Chini &Gupta 1997).  Construction with wooden materials does not provide builders with such broad options and alternatives.  Moreover, buildings that are steel-framed can easily serve the requirements of acoustic performance, especially for the residential structures than the timber framed ones. This is possible if careful detailing is done for the walls, finishes on the floor, flanking and services penetrations so as to provide for reliable and proven acoustic performance (Chini &Gupta 1997). Similarly, for the external walls that where thermal and acoustic performances are required to be provided, a construction of infill that is steel-framed will work as the best solution. The provision of insulation is done within the frame which offers great thermal properties.  The infill solutions also give a robust wall that has no gaps left between the main structure and the wall. This is a problem that can occur in case the walls are made of wooden blocks. Furthermore, the erection of steel structures can be done faster than wooden structures (Chini &Gupta 1997). This can be attributed to the accuracy and predictability of steel components which speeds up the construction process and also provide for follow-on trades. This gives time savings in the construction or build program than construction of wooden structures that requires a lot of modification for the timber to be used. The speed of putting up structures is a major criterion that makes allows steel to be selected of timber. The short periods of construction leads to a lot of savings in the preliminaries at the site, reduced charges on applicable interest and also makes it possible for returns on investments to be realized earlier (Dubina & Ungureanu, 2006).  

Moreover, steel metal can be used in combination with many other materials in the building of structures such as buildings or bridges. The structures of composite steel-concrete are widely used in the construction of such structures (Oehlers, & Bradford, 1999). Unlike wood, steel can be used together with concrete to take advantage of the best attributes of these materials which in turn make the construction to be very economical and efficient. The connection of steel and concrete allows the transfer of strengths to the members of the composite a behavior that is quite different from other materials. More specifically the connection transfers the forces in the concrete to the steel and vice versa in order to avert a case of separation of the two materials. In many of the modern buildings’ flooring systems, steel that is cold-formed is used with concrete slabs. Here, steel acts as an integral formwork for the concrete material enabling the achievement of a composite action. These composite are becoming more useful in the construction of high-rise buildings because they allow for more strength for supporting other building materials. On the other hand, timber rarely allows for the combination with other building materials to provide enough supportive frameworks for such buildings or other structures like bridges (Yadav & Garg, 2015). Otherwise, timber can be used to make structures without combining with other materials.

Besides, products of steel can be recycled without losing or degrading any of the prosperities inherent to it. This means that steel as a building material is very efficiency in managing environment degradation. The energy required for manufacturing the steel products has decreased considerably. Thus, when steel is evaluated against various issues sensitive to the environment, it is very preferable as compared to timber. Moreover, the raw materials required to manufacture steel exist in plenty since iron is an abundant mineral (Chini &Gupta 1997). Even though timber is renewable, it cannot be more sustainable than steel.

 

 

References

Muttoni, A. (2011). The art of structures: Introduction to the functioning of structures in architecture. Abingdon, Oxford, UK: EPFL Press/Routledge.19-24

Parke, G., Nigel, H., & Institution of Civil Engineers (Great Britain). (2008). ICE manual of bridge engineering. London: Thomas Telford.

Chini, A., Gupta K. (1997).A Comparison between Steel and Wood Residential

Framing Systems. Journal of Construction Education. University of Florida

Gainesville, FL. Vol. 2, No. 2, pp. 133 – 145

International Conference on Advances in Steel Structures, Chan, S. L., Teng, J. G., Chung, K. F., Hong Kong Polytechnic University., Hong Kong Institution of Engineers., & Hong Kong Institute of Steel Construction. (2002). Advances in steel structures: Proceedings of the Third International Conference on Advances in Steel Structures, 9-11 December 2002, Hong Kong, China. Amsterdam: Elsevier.963

Oehlers, D. J., & Bradford, M. A. (1999). Elementary behaviour of composite steel and concrete structural members. Oxford: Butterworth-Heinemann. 19-20

Case, J., Chilver, H. C., & Ross, C. T. F. (1999). Strength of materials and structures. Oxford: Butterworth-Heinemann. 268-270

Dubina, D., Ungureanu V.,(2006).Steel - A New and Traditional Material for Building. Proceedings of the International Conference in Metal Structures 2006. 149.

 Yadav , S. Garg, V.(2015).Advantage of Steel Diagrid Building Over Conventional Building. International Journal of Civil and Structural Engineering Research. Vol. 3.1.400-404