Which frame is better to choose: steel structures or reinforced concrete?

Rauta together with the Ukrainian Steel Construction Center association conducted a comparative analysis of the production or warehouse building frame construction, the purpose of which was to determine the best solution of load-bearing structures for the customer regarding cost and terms of manufacturing, delivery and installation.

A warehouse building with an area of ​​1,900 m², the construction of which is planned in the Kyiv region, was chosen for the comparison of frame construction technologies. The building has a two-span layout (18+18 m) with a centrally located column axis. Consequence classe – СС2, service lifetime – 50 years.

Steel frame with welded structures

Principal scheme of the frame

Structural solutions of the steel frame:

• The scheme is made with rigid anchoring of the columns to the footing and hinged roof trusses
• Footing for columns are monolithic, columnar
• Columns are installed with a c/c distance 6.6 m in the longitudinal direction and 6 m at the ends of the building
• Columns made of hot-rolled profiles are spaced 400 mm apart in rows of trusses and welded into a box at the ends of the building
• Trusses with a span of 18 m from bent-welded square profiles, cover beams at the ends of the building and girders from hot-rolled profiles
• Purlins of the covering are installed with a steps of 3 m according to the sectional beam installation diagram
• Horizontal beams along the upper belt of the trusses and vertical beams from bent-welded profiles
• The material of the frame structures is S245 and S255 steel grade

Steel frame made of light purlins

Structural solutions with light gauge steel frame (LGSF):

• The scheme is made with rigid anchoring of the columns to the foundations and hinged roof trusses
• Foundations for columns are monolithic, columnar
• Columns are installed with a c/c distance 4 m in the longitudinal direction and 6 m – at the ends of the building
• Columns made of galvanized paired Σ-profiles
• Truss with a span of 18 m made of galvanized Σ-profiles, roof beams at the ends of the building and purlins – galvanized C-profiles
• Roofing purlins are installed with a c/c distance 1.5 m according to the sectional beam diagram
• Horizontal trusses along the upper belt of the trusses and vertical trusses are made of galvanized purlins
• Frame structure material – steel S355 GD

Precast reinforced concrete frame

Principal scheme of a reinforced concrete frame

Structural solutions of the precast reinforced concrete frame:

• Columns c/c distance is 4.2 and 6 m in the longitudinal direction and 6 m at the ends of the building
• Sloped footing for square columns
• Beams with a span of 18 m have T-shaped section, beams with a span of 6 m are I-shaped
• Purlins are made of reinforced concrete, installed with 3 m c/c distance

Cost comparison*

* Indicated mid-market prices including VAT as of June 2024.

** The cost of hot-rolled steel is indicated including technological waste, which is approximately 5%, and do not take into account the cost of steel for secondary structures of walls, gates, doors, windows, stairs, etc.

*** It doesn’t not include the cost of bent elements, embedded parts, secondary structures of walls, gates, doors, windows, stairs, etc.

According to the results of the analysis, the total cost of a steel welded frame is 14% less, and LGSF is 22% less than the cost of prefabricated reinforced concrete structures, which amounts to UAH 1,014,000 and UAH 1,801,000 respectively.

Significant savings in the construction budget when using steel structures is achieved due to the lower cost of welded frame structures by 7.4%, foundations by 34.5%, logistics costs by 42.5% and installation work by 20%. For LGSF, the cost savings on the frame compared to reinforced concrete structures is 14.6%, foundations – 29.2%, logistics costs – 57% and installation work – 29.4%.

The installation cost of frames is calculated for a building with fire resistance of load-bearing structures REI 15 without additional fire protection. If it is necessary to ensure the fire resistance of the load-bearing structures at the level of REI 30, steel frame might need fire protection and that will equalize their price with reinforced concrete, which in this case doesn’t not need additional protection. When the requirements for fire resistance are increased to REI ≥ 60, the total cost of steel solutions may become slightly more expensive than reinforced concrete, but at the same time other advantages of steel construction will remain.

An additional advantage of using a steel frames is the fast construction time, which as of June 2024 averaged 1.5 months compared to 6 months for a precast reinforced concrete frame. This allows the customer to build the facility faster and start returning the investment earlier.

Also, the installation of facades and roofs for a steel frames is simpler and does not require additional embedded parts, as for precast reinforced concrete structures. Due to the fact that the steel frame is 98% recycled or can be reused, the metal structure building complies with the principles of sustainable development, which adds to investment more attractiveness and increases the number of points for LEED and BREAM certification.