Discusión del Objetivo Específico N° 2: Determinar los indicadores que representan

As mentioned above, a constructive research strategy has been employed for this project with a subordinate case study strategy for the field work. The first part of the research involved a detailed literature review and the outcome of this part is recorded in Chapters 5 to 8. The case study focused on the works of a steelwork subcontractor for the fabrication and erection phases of the Assembly Hall structural frame as detailed in Chapter 9. As the first part of the research was literature-based, the rest of this subsection focuses on the methods used for the case study.

29

The steel production was split between the Subcontractor factories in Portugal and Romania. The delivery of materials to site, the pre-assembly of the roof structure at ground level and the lifting of the heavy roof were sublet to other specialist Subcontractors. In addition to the activities of the main steel Subcontractor (Level 1), this research only covers the on-site activities of these other Subcontractors (level 2). Other entities involved in the monitoring and supervision of the works included the Contractor, Engineer, Employer and End-user as defined in Chapter 9.

The researcher was involved from the beginning to the completion of the steelworks as part of the Employer team. The data for this case study was collected during routine project quality controls. It is worth noting that, without the needs of this research, the researcher would have had access to the same level of project information. However, in addition to being a participant, the researcher assumed the role of observer thereby taking note of information that other participants would not identify as a matter of course.

According to Proverbs and Gameson (2008), a case study methodology can involve a number of data collection methods. In this case, data was collected from project documentation review as well as through observations at meetings, during site supervisions and factory inspections. Reviewed documentation included contractual documents, technical specifications, drawings, working procedures, correspondences (letters and e-mails), minutes of meetings, progress reports and quality assurance documents. The physical artefact itself, the steel frame, was inspected as it was being constructed piece by piece. All the data was considered primary information as it was collected in real time and at source during construction of the steel frame. Both the description of the activity and the researcher’s personal reflection at the time were recorded in a notebook.

Care was taken in interpreting the project information as it was produced for a different purpose to that of this case study (Yin, 2009). Thus the researcher’s involvement as inspector of the works had to be somewhat detached from the research in order to minimise bias. Furthermore, the Subcontractor was expected to behave differently during inspections involving the Employer team (as compared to when no Employer inspections were underway). Thus, in addition to the case study being focused on what was done rather than

30

why it was done, a number of cases and documents had to be considered in order to paint a true reflection of everyday practices.

4.6.2

Data analysis

The result of this case study is a detailed record of the processes and steel quantities involved in the fabrication and erection of the structural steel frame, which is covered in Chapter 9 and the associated Appendices 1 to 4. This information alone is considered vital for the building industry but the researcher performed further analysis of the data in Chapter 10 to estimate the carbon footprint of the concerned steel frame.

The carbon footprint of the building considered in the case study was calculated using the BCSA Carbon Footprint Tool (v3) for the cradle to end-of-erection boundary case. This user- friendly tool, prepared by the Steel Construction Institute (SCI) for BCSA, comes with a detailed assessment methodology and user guide (SCI, 2011). The tool is very simple to use once the emission factors, boundary and methodology are established. The assumptions taken for the carbon footprint calculations carried out for this research are summarised in Chapter 7.

4.7

Summary

This chapter explored the subject of philosophy and its influence on the research conducted and covered by this thesis. Following a review of the overarching epistemology, ontology and axiology, the research onion in Figure 4.1 was adopted in defining the rest of the research philosophy stages used in this study. The selected approach, which covers all the layers of the research onion, is summarized in the flowchart in Figure 4.2 below.

The findings and analysis of this research are documented in Chapter 10, where the disaggregated data from the case study is analysed using the BCSA Carbon Footprint Tool and compared with average aggregated figures obtained from existing literature. Consistent with the adopted constructive research theory, the results will either confirm or falsify the current beliefs (Jarvinen, 2007). The recommendations for further studies on the remaining gaps in knowledge identified through this research are detailed in Chapter 11.

31

32

5

Steel

This section reviews the history of steel and how the demand for steel has risen to its present levels. The steelmaking process is then covered, including the impact of chemical composition, heat treatment and fabrication on the engineering properties of steel.

5.1

History of steel

Steel is an alloy of iron, the metal which facilitated the industrial revolution of the 18th Century. Steel’s prominence came in 1855 through the invention of the Henry Bessemer converter, whereby hot air was blown through liquid iron in the furnace in order to remove impurities. This process was immediately adopted by the UK steelmaking industry (Worldsteel, 2012b).

The Bessemer process facilitated the mass production of steel and brought about the second industrial revolution. This resulted in affordable steel products, transforming steel from a precious metal to one of the most common materials of this era. It is used in almost every sector including construction, machinery, automotive and transport. Apart from the change introduced by Robert Durrer in 1948 (IIMA, 2015), where hot air was replaced by oxygen for improved efficiency, the Bessemer process is still being followed in modern steelmaking.

By the turn of the 20th Century, there were large steelmaking companies in Europe and the

USA, with production figures overtaking those of the UK (BCSA, 2006). Consequently, national tariff barriers existed for a good part of the 20th Century until the formation of free trade areas in Europe and Canada.

The steady increase in production that followed World War II was affected by the 1974 global energy crisis as shown in Figure 5.1 below. Together with a saturated market in developed countries, the crisis brought growth in steel production to a halt in the 1980s. The revival in demand came in the 1990s through developments in China, which in 2009 consumed about two thirds of the global iron ore. A steady growth has been maintained by demand in other developing regions, particularly in the other BRIC countries of Brazil, Russia and India (BCSA, 2006).

33

Figure 5.1: steel production growth rate in million tonnes (Worldsteel, 2012b)

Steel was a strategic national industry that benefitted from state support until the fall of the Soviet Union, among other things, led to a spate of privatisations in the early 1990s. Major acquisitions and mergers have recently led to the creation of global conglomerates such as ArcelorMittal. At present, China is the centre of attraction for trade in all things metal. It is importing ores from Australia and Brazil, machinery from Australia and Europe, scrap metal from the USA, steel and iron from Australia and Europe and, in return, exporting vehicles to the rest of the world (Allwood and Cullen, 2012).

5.2

What is steel?

Steel is a versatile structural material because of its combination of high strength, good strength to weight ratio, a wide range of material properties and product form, 100% recyclability, ready availability and affordability. It is a ferrous (i.e. it contains iron, as opposed to non-ferrous metals such as copper, aluminium and zinc) alloy with a number of other elements added in small quantities to achieve a variety of chemical compositions. The stock products from the steelmaking industry are structural sections, bars and plates, which are transformed into useful products through manufacturing. A small proportion of steel production consists of heavy forging and castings (SCI, 2003).

With strength levels ranging from 250N/mm2 to 2000N/mm2, steel can be formed into a wide range of different products. It has a constant modulus of elasticity up to yield strength but still has a high capacity of deforming plastically, making it a ductile material with good

34

fracture toughness. Other useful properties include low thermal expansion and high melting temperatures (Allwood and Cullen, 2012).

The main problems of steel in the construction industry are corrosion and fire resistance. Although normal structural steel maintains strength to 300oC, it progressively weakens at higher temperatures. Steel also needs to be protected from corrosion in adverse conditions. Both the hot strength and corrosion resistance of steel can be improved by chemical formulation but currently it is more cost effective to provide external protection (SCI, 2003).