Comparing the overall mechanical properties of the specimens being annealed at the two investigated temperatures with those without annealing, a general trend was found that

yield strength increased with annealing temperature, as did the elastic modulus while maintaining yield strain.

Here, the step mold

yield strength (YS) aging curve are compared.

All the mechanical properties, tensile strength,

yield strength, and elongation after breakage, increase firstly and then decrease with the content of aluminum increasing.

where [P.sub.n0] is the nominal axial compressive strength of the section (N), [P.sub.p] is the superimposed strength of the section (N), [F.sub.y] is the

yield strength of steel (MPa), [A.sub.s] is the area of steel cross section (mm2), [f.sub.ck] is the compressive strength of concrete (MPa), [A.sub.c] is the area of concrete cross section (mm2), [A.sub.sr] is the area of continuous rebar (mm2), and [F.sub.yr] is the

yield strength of the rebar (MPa).

Key takeaway from the displacement plot is that

yield strength (YS) has the biggest influence in reducing the peak displacement.

Regression equations are developed for the tensile strength,

yield strength and elongation using the statistical software.

Table 1 Chemical and mechanical properties of HSLA steel Chemical composition, wt % C Si Mn P S 0.10 0.10 1.00 0.02 0.025 Mechanical properties

Yield strength, MPa Tensile strength, MPa Elongation, % 437 490 26

In 1978, Server proposed the following relationship for estimating the dynamic

yield strength of a metallic material based on the force at general yield [F.sub.GY] [4]:

On the other hand, while the

yield strength increases, the tensile strength decreases.

If Y [approximately equals] 1, according to formula (2) and (6), the relations among the material

yield strength, applied stress, and the allowed corrosion crack can be obtained, as shown in Figure 5.

Two sizes of bolted splices: regular size and longer size, and two steel materials: regular steel and low

yield strength steel were investigated.

Except in Euro code 2 (ECS 2004) that a set of more stringent requirements are specified for HSC beams, these empirical rules are not dependent on concrete and steel

yield strength. However, as reported in a series of theoretical studies conducted on flexural deformability carried out previously by the authors (Ho et al.