Ultimate Axial Strength of Concrete-Filled Double Skin Steel Tubular Column Sections

Figure 3

Expression trees for the proposed model. (a) Function 1. (b) Function 2. (c) Function 3. (d) Function 4. (e) Function 5. (f) Function 6. (g) Function 7. (h) Function 8.

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)