Structural steelwork: market overview & position

Structural steelwork has a number of key advantages over insitu concrete and traditional load-bearing construction forms. It maximises the use of off-site fabrication, is of high quality and gives a high degree of dimensional accuracy. Off-site fabrication minimises on-site construction activities, resulting in improvements in programme and a reduction in working at height.

Market overview

The British Construction Steelwork Association has suggested that 2007's output was 1.6m tonnes and that most steel fabricators have a healthy orderbook.

Structural steelwork is the material of choice for many markets including retail, commercial offices, schools and industrial facilities. Its high strength to weight ratio makes it the natural choice for structures requiring larger spans unobstructed by columns. Steelwork, however, generally loses out to concrete for the medium/high-rise residential schemes that have sprouted in major urban centres recently through concrete's ability to minimise structural floor zones, provide a flat soffit for ease of services distribution and inherent acoustic and fire resistance properties.

However, as structures get higher, the weight savings that can be achieved through structural steelwork tip the balance in its favour by reductions in column and foundation requirements.

Steelwork has benefited from a buoyant market for years driven by market activity across most sectors. It remains to be seen what effect the current credit crunch will have on UK steelwork sales, but its limited reliance on the residential market, other than for bar reinforcement, should cushion it. Furthermore, as the schools' rebuilding programme gathers pace any slow-down in the residential sector will be further offset.

Legislative framework

New designs are generally compliant with BS5950 structural use of steelwork in building and BS5400-3 Code of Practice for the design of steel bridges. Eurocodes EC3 (design of steel structures) and EC4 (design of composite steel and concrete structures) will take effect over the next three years and UK designers will need to make the transition. The migration to Eurocodes is unlikely to affect the attractiveness of one material over another.

Codes are giving an increased focus to dynamic performance, the effects of which lighter steelwork structures, with larger spans, are much more vulnerable.

The greatest change in legislation is the emphasis on mitigating the effects of climate change through reducing the carbon footprint of facilities, not only during construction but also during use and eventual demolition.

Steelwork is a reusable material. It can be recycled indefinitely without any loss of performance and the use of 60% recycled steel in the manufacturing process is typical in the UK. Recovery rates from UK sites are high, with more than 90% of steelwork components recovered. There is virtually no waste in the manufacturing and fabrication processes.

Concrete structures, however, with greater mass have a greater ability to control internal climatic conditions.

A rough guide

The UK market is expected to remain strong in the short to medium term. The global demand for steel, and the effects of the strong China economy, has led to significant increases in raw costs since the mid-2000s. Raw material costs usually account for approximately 30% of the total tonnage costs, with fabrication, painting and transport accounting for 45%. Design and erection accounts for the remainder.