Leaderboard

here is a very good discussion. OmegaFactorDiscussion.pdf

Yes , you r right. ubc 97 requires us to use those combinations only for members supporting discontinuous system. Where ever uniform ductility demand is lacking in vertical members ( Bangale's book). It seems logical to extend this requirement to connections in steel structures.

No clue about ASD. Your last resort would be UBC 97 Commentary.

MIDAS SET Column Concrete Shear Capacity Problem MIDAS SET 3.2.1 Column Concrete Shear Capacity Problem Link for CIVILEA topic MIDAS SET is a good tool to verify individual sections output. It incorporates a simple input data form on the left side and the detailed equations and output in the right pane. Despite of its good tools and features, I faced a problem while I was calculating the column shear capacity (concrete) manually and trying to verify it with MIDAS. To my astonishment it gave me almost double the value which I got using ACI-318 chapter 11 equation 11-4 for concrete shear capacity under axial loads. I will show you here the detailed steps to prove my point. If you find anything misleading or want to share your thoughts please respond. I have written an email to MIDAS and let’s see when can I get the response. Solve a simple column example B=500mm H=500mm Cover=50mm so d = 450mm Axial Factored Load is 700kN Compression f’c = 45 MPa Ag = 500x500 = 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 = 0.75x307.91 = 230.93 kN whereas in MIDAS software, it gives Phi Vc in both the directions equal to 612.0 kN. This value is even more than 2 times the value we calculated from ACI equation. I am doubtful to use this software for verification because of this error.