SR-3 RAC 120.0 × 4.0 398.2 0.3 132.5 1,622.4 1,133.6 3.59 21.17

SN-6 Normal 120.0 × 4.0 829.0 0.6 88.4 1,907.4 1,250.2 2.44 5.12

SR-6 RAC 120.0 × 4.0 796.5 0.6 91.9 1,981.0 1,291.9 2.11 4.25

© ASCE 04016219-2 J. Struct. Eng.

Table 2. Material Properties of Stainless  Steel

Sectional type Initial elastic modulus E0  (GPa) 0.2% proof stress σ0.2  (MPa) Strain-hardening exponent n0 Poisson’s ratio Tensile strength

fu (MPa)

Circular 202.1 362.1 5.6 0.265 721.7

Square 198.3 385.1 5.1 0.306 715.0

Table 3. Mix Proportions of  Concrete

Concrete type Cement (kg=m3) Sand (kg=m3) Natural coarse aggregate (kg=m3) Recycled coarse aggregate (kg=m3) Water (kg=m3) Fly ash (kg=m3) Additional water reducer (kg=m3 )

Normal concrete 320 990 720 — 170 200 24

Recycled aggregate concrete 320 990 360 360 170 200 24

obtained by crushing waste concrete taken from previously tested CFST specimens. Carbonate aggregate, i.e., dolomite, was chosen as the natural coarse aggregate with a size range of 5–20 mm. Three

aggregate grades, i.e., 5–10 mm, 10–20 mm, and  20–30 mm, were made for the recycled coarse aggregate. The physical proper- ties of the natural coarse aggregate are as follows: unit weight 2,605 kg=m3, bulk density 1,405 kg=m3, crushing value 15.4%, and water absorption 0.56%; while those for the recycled coarse aggregate are unit weight 2,394 kg=m3, bulk density 1,120 kg=m3, crushing value 16.2%, and water absorption 3.04%. Obviously, the recycled coarse aggregate had lower density and higher absorption than the natural aggregate due to the presence of residual mortar attached to the recycled aggregate  particles.