How does RAM calculate k factors for columns? My calculations for some columns do not match the output.
What criteria does it use to determine which beams are framing into the connection? Can you modify the criteria?
-Are beams that frame in at an angle considered?
-Are beams which frame in just off the column considered?
-What does it do when beams only frame in one direction for the axis perpendicular?
RELATED: Is there a single source to find all of the calculations RAM uses? I do not like black boxes. I would like to know what RAM is considering and what it is assuming.
Thanks
Take a look at the Ram Concrete Column Manual (v14.05) Section 4.3 "Slenderness", and the Concrete Analysis Manual Section 2.5.5 "Effective Length" for details.
We only consider beams directly framed into the column. We do consider skewed beams based on some simple trigonometry. We do consider the assigned cracked section factors for beams and columns in the calculation.
We do not consider the slab stiffness, only beams. For Column and 2-way slab systems the K factors should be user assigned.
Most of the calculations are shown in reports, for the cases where something is not shown sufficiently then check the manual for details. If there still isn't enough information for you come back to this forum (or sometimes a test model can be made to confirm things)
Answer Verified By: B.Greger
Thanks. I did find most of what I was looking for in the manual and your response.
Can you elaborate on how skewed beams are handled?
Does RAM take the cos(skew) * E_b I_b / l_b ?
That sounds right, the cosine of the beam to column axis skew angle reduces the beam EI/L term in the numerator which in turn affects the K value (when calculated per nomograph)