Consider a nonslender column with cross-section as in Figure 13.20 and d1 = 40 mm, As1 = 803.8 mm2 , d2 = 225 mm, As2 = 401.9 mm2 , d3 = 375 mm, As3 = 401.9 mm2 , d4 = 40 mm, As4 = 803.8 mm2 , h = b = 600 mm. The materials of the RC column are f ′ c = 27.5 MPa, fy = 413 MPa.
Calculate the interaction diagram for the following cases:
(1) unstrengthened member,
(2) strengthened member with n = 3 layers of carbon-epoxy FRP with properties f ∗ fu = 3, 800 MP a, ε ∗ fu = 0.0161, tf = 0.5 mm.