Thoughts on tall CMU columns
Thoughts on tall CMU columns
(OP)
I was asked if it was feasible to use a 25' tall reinforced cmu column in an atrium. The columns would be surrounded by glazing on both sides with bond beams at the mid height and top. Initially I thought it sounded a little tall for a cmu column, however, I ran some numbers just as a gut check to get an idea and it seemed fine. I just wanted to hear some opinions on this. I don't commonly use tall CMU columns.
25' column taking approximately 10' of trib wind area at approximately 28psf(already factored by .6 for asd). The columns would have a bond beam at midheight for the first floor, however, it would not have bracing in the other direction for the full 25'. I assumed simply supported column with effective height of 25'.
I assumed a 16"x16" column with 4 #6, f'm=2500psi, fy=60
H/t = (25)(12)/15.63 = 19.2 which is acceptable
Using the load combination of D+.75W+.75Lr and my total moment including accidental moment due to eccentricity came out to approximately 17.32k-ft
Axial load at midpoint of approximately 14kip.
I developed a P-M diagram and the loads fell safely within it. Double checked some masonry and steel checks and everything seemed like it should be adequate.
Just wanted to see thoughts on any possible issues that could arise or items that I may be overlooking.
25' column taking approximately 10' of trib wind area at approximately 28psf(already factored by .6 for asd). The columns would have a bond beam at midheight for the first floor, however, it would not have bracing in the other direction for the full 25'. I assumed simply supported column with effective height of 25'.
I assumed a 16"x16" column with 4 #6, f'm=2500psi, fy=60
H/t = (25)(12)/15.63 = 19.2 which is acceptable
Using the load combination of D+.75W+.75Lr and my total moment including accidental moment due to eccentricity came out to approximately 17.32k-ft
Axial load at midpoint of approximately 14kip.
I developed a P-M diagram and the loads fell safely within it. Double checked some masonry and steel checks and everything seemed like it should be adequate.
Just wanted to see thoughts on any possible issues that could arise or items that I may be overlooking.






RE: Thoughts on tall CMU columns
RE: Thoughts on tall CMU columns
RE: Thoughts on tall CMU columns
Just FYI the columns will be surrounded by glazing for an atrium. It will be a two story building, however, in this area the columns will be unbraced in the primary axis running from ground to roof(spanning 25'). The axial loads on them will be fairly low (unless the truss design changes), however, they will be subject to a larger moment due to the wind acting on the glazing around them.
RE: Thoughts on tall CMU columns
RE: Thoughts on tall CMU columns