Nonlinear Material Behavior of the Bridge Components - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 74

In Europe, EC2 [ 2.27 , 2.28 ] gives principles and rules for reinforcement,
which is in the form of bars, decoiled rods, welded fabric, and lattice girders.
They are not applicable to especially coated bars. One of the required prop-
erties of the reinforcement is that the material should be placed in the hard-
ened concrete. The steels covered in EC2 are that in accordance with
EN10080 [ 2.14 ] . The required properties of reinforcing steels shall be ver-
ified using the testing procedures in accordance with EN 10080. It should be
noted that EN 10080 refers to a yield strength R e , which relates to the char-
acteristic, minimum and maximum values based on the long-term quality
level of production. In contrast, f yk is the characteristic yield stress based
on only the reinforcement used in a particular structure. There is no direct
relationship between f yk and the characteristic R e . However, the methods of
evaluation and verification of yield strength given in EN 10080 provide a
sufficient check for obtaining f yk .
2.4.2 Properties
According to EC2 [ 2.27 , 2.28 ] , the behavior of reinforcing steel is spec-
ified by main properties comprising yield strength ( f yk or f 0.2k ), maximum
actual yield strength ( f y,max ), tensile strength ( f t ), ductility ( e uk and f t / f yk ),
bendability, bond characteristics ( f R ), section sizes and tolerances, fatigue
strength, weldability, and shear and weld strength for welded fabric and
lattice girders. EC2 [ 2.27 , 2.28 ] applies to ribbed and weldable reinforce-
ments, including fabric. The permitted welding methods are given in
Table 2.12 ,while Table 2.13 gives the properties of reinforcement
suitable for use with EC2. The properties are valid for temperatures
between 40 and 100 C for the reinforcement in the finished structure.
It should be noted that the values for the fatigue stress range with an upper
limit of bf yk are given in Table 2.14 . The recommended value of b is 0.6.
The rules for design and detailing specified in EC2 are valid for a specified
yield strength range, f yk ¼ 400-600 MPa. The surface characteristics of
ribbed bars shall be such to ensure adequate bond with the concrete. Ade-
quate bond may be assumed by complying the specification of projected
rib area, f R , with minimum values of the relative rib area, f R , given in
Table 2.14 . The yield strength f yk (or the 0.2% proof stress, f 0.2k )and
the tensile strength f tk are defined, respectively, as the characteristic value
of the yield load and the characteristic maximum load in direct axial ten-
sion, each divided by the nominal cross-sectional area. The reinforcement
shall have adequate ductility as defined by the ratio of tensile strength