I encountered a strange problem in MIDAS SET for concrete shear capacity of a column.
Solving a simple column example;
Cover=50mm so d = 450mm
Axial Factored Load is 700kN Compression
f’c = 45 MPa
Ag = 500×500 = 500 mm²
From ACI-318(05M) chapter 11, equation 11-4 we get;
Vc = 0.17 (1 + Nu/14Ag) (f’c^0.5) b.d
Where Nu/Ag term should be in N/mm²
Nu is –ve for TENSION and +ve for compression
So putting all these values in this equation we get;
Vc = [ 0.17 ( 1 + 700*1000/14/500² ) (45^0.5) 500 x 450 ] / 1000 = 307.91 kN
and Phi Vc = 0.75×307.91 = 230.93 kN
whereas in MIDAS software, it gives Phi Vc in both the directions equal to 612.0 kN. This value is more than 2 times the value we calculated from ACI equation.