​Reinforced Concrete vs Steel

Concrete is a mix of aggregate, cement, reinforcement (for reinforced concrete) and water. It is strong in compression and weak in tension. Insitu or precast or ready-mixed concrete (pumped or compacted) can be chosen for design, depending on the needs of the structure and the requests of the client. The type of reinforcement (mild, stainless, plan, etc) and the composition of the mix can also be designed to suit the structure. Formworks used are usually made out of steel, timber, or plastic that can help keep liquid concrete in shape until it forms into a solid state.

Steel has a good strength to weight ratio and has elastic behavior until yield strength occurs. It can be formed into many different sectional sizes and produce great connections with welds and other steel connection designs. Steel characteristics or grades are chosen based on serviceability requirements of the structure. Such characteristics include strength, weldability, and degree of carbon resistance.

Advantages

Reinforced Concrete

●     High strength and provide long spans (especially when using prestresed concrete)

●      Good durability, waterproofing properties, weather resistance, and chemical resistance, so not a lot of maintenance cost needed

●      Provides robustness for precast structures due to monolithic nature. Disproportional collapse can be prevented by careful detailing.

●      Flexible for late design changes

●      Typical, faster, and cheaper (i.e. services can be installed earlier in the construction schedule)

●      Provides resistance from lateral loads by reinforced concrete core walls

●      Suitable for swimming pools due to some concrete having waterproof properties

●      Readily available in local markets

●      Fire resistant properties for good thermal insulation

●      Can achieve a 60 year design life and can be recycled at end of life

●      Provides aesthetics in buildings by using precast or insitu concrete to create unusual shapes at a small cost (i.e. curved beams, circular columns, shells, concrete columns inside walls)

●      Provides good sound insulation and vibration resistance because of the heavy mass property of concrete. Great for educational and residential buildings in order to prevent sound and vibration passing and disruption through individual units and for hospitals and laboratories that contain sensitive equipment.

●      Reinforcement can be bent prior to site delivery to prevent delivery and inconvenience of handling long rebars

  Steel

●     ​Light weight property so foundation does not have to be big in size, thereby reducing cost

●      High strength and is not affected by time-dependent stresses (creep, shrinkage, etc)

●      Structure loading path is sufficient so it is not required for transfer structures

●      Simple to construct and assemble steel sections due to option of pre-fabrication

●      Common and flexible for pile foundations

●      Less columns needed (no core walls)  so more interior space in plan layouts

●      Suitable for long span structures

●      Less structural depth in steel sections so more clear headroom available

●      Steel trusses provide design of hanger columns and structural walls

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Disadvantages

Reinforced Concrete

●     Transfer structures are required for load paths

●     Concrete elements are much heavier than steel so the structural design requires heavier and costly foundations

Steel

●     Less available and common in local markets so demand makes steel more expensive

●      Longer procurement times

●      Should not be used for water-tight structures

●      More maintenance cost because of corrosion

●      Requires more expensive fire resistance treatment and special corrosion protection measures

●      Not a lot of flexibility due to fixed layouts and fixed fabrication orders.

●      Changes in steel section orders will cause delay and cost

●      Method of bracing gives unaesethtic effect and gives less stiffness and robustness for lateral stability than core walls and RC beam-column frame. All beam to column connections would need to be moment (fixed) connections to make the structure more resistant to wind.

●      Require experienced and skilful labor for installation

●      When in a highway, site access is an issue for steel structural members