BS 4449

BS 4449: 2005 Steel for the reinforcement of concrete weldable reinforcing steel, bar, coil and decoiled product

Last updated 23/05/2008

This was a full revision of the standard and defines three grades of reinforcement conforming to BS EN 10080; B500A, B500B and the 'new' B500C. The characteristic yield strength has been increased to 500 MPa and the tensile properties and ductility of the three grades are described in Table 1.

Characteristic tensile properties

Grade	Yield Strength R_e MPa	Tensile/yield strength ratio R_m/R_e	Total elongation at maximum force, A_gt %
B500A	500	1.05^a	2.5^b
B500B	500	1.08	5.0
B500C	500	1.15, < 1.35	7.5
^a R_m/R_c characteristic is 1.02 for sizes below 8 mm ^bA_gt characteristic is 1.0% for sizes below 8 mm Values of R_c specified are characteristic with p = 0.95 Values of R_m/R_c and A_gt specified are characteristic with p = 0.90 Calculate the values of R_m and R_c using the nominal cross sectional area
The absolute maximum permissible value of yield strength is 650 MPa.

The three grades conform to the three recommended ductility classes in BS 1992-1-1:2004 (Eurocode 2). It should be noted that below 8mm diameter, reinforcing steel to BS 4444 does not comply to BS EN 1992-1-1 with respect to ductility. This is not the only occasion where BS 4449:2005 has had to take into account the requirements of BS EN 1992-1-1. For instance, the scope of Eurocode 2 is limited to ribbed reinforcement with strengths between 400 and 600 MPa. Hence, plain round bar, grade 250, has been dropped from BS 4449 (its use in structural applications was in severe decline anyway: it is generally more expensive and there is no longer any advantage in bending radii in links etc). Grade 250 dowel bars will be covered in BS EN 10025-1 or in concrete pavements BS EN 13877-3.

The apparent increase in characteristic yield strength from 460 MPa to 500 MPa should make very little practical difference to design, as in both BS EN 1992-1-1 and the 2005 revision of BS 8110 the partial safety factor, ³m = 1.15. For those who to continue to need 460 grade to BS4449:1997, , eg fulfilling contracts where the design was to BS 8110:1997 (and ³m =1.05), it is probable that rebar will be dual certified to both BS 4449:1997 and BS 4449:2005 for the next few years. However, designers must not use the 500MPa with BS 8110:1997.

BS 4449:2005 uses the term 'bar' for ribbed reinforcing steel. The terms 'rod' and 'wire' should be restricted to describe reinforcing steel in coil, or wire in reinforced concrete products.

BS 4482: Cold reduced wire for the reinforcement of concrete

Last updated 01/05/2008

This was a full revision of BS 4482:1985, in line with BS EN 10080. It now incorporates plain, indented and ribbed wire, coiled or decoiled. Grade 250 has been incorporated. The characteristic strength of the high yield steel has been increased to 500 MPa and the ductility aligned with B500A in BS 4449:2005, but no fatigue performance is specified.

Most wire to BS 4482 is unlikely to comply with BS EN 1992-1-1. To avoid any confusion, any design to BS EN 1992-1-1:2004 should have reinforcement specified to BS 4449:2005. Similarly any fabric used for structural purposes should be manufactured to BS 4483 using material specified to BS 4449:2005.