"Positive" moments
"Positive" moments
(OP)
Hello,
Task: I need to design a building with 6 stories.
Problem: After calculation, I've got "positive" (bending moments on bottom side) moments on beams above columns (supports) with vertical load.
Possible reason: Shear walls are more rigid than columns so due to uneven vertical displacements I got this untypical moment diagram.
Question: How to solve this problem? How can I design frame on seismic forces?


Thank you in advance..
Task: I need to design a building with 6 stories.
Problem: After calculation, I've got "positive" (bending moments on bottom side) moments on beams above columns (supports) with vertical load.
Possible reason: Shear walls are more rigid than columns so due to uneven vertical displacements I got this untypical moment diagram.
Question: How to solve this problem? How can I design frame on seismic forces?


Thank you in advance..






RE: "Positive" moments
BA
RE: "Positive" moments
IR
RE: "Positive" moments
I think that's unimportant, my confusion is unusual moment diagram under gravity load.
Lateral force resisting system are frames with shear walls.
Software: Radimpex Tower (www.radimpex.rs)
Maybe i wasn't clear enough, under gravity loads I get positive moments above columns (supports).
Link
Thank you for your answers..
RE: "Positive" moments
IR
RE: "Positive" moments
I checked all those things and got nothing.
Planar support is rigid so there should not be any "hanging" of columns.
I just wanted to check, have this ever happened to you?
RE: "Positive" moments
For example if the beam spans not equal, Therefore the positive moment that applied on the middle span is vary large according of the deffirance in spans lengths, so the moment wont totaly convert to nigative above the support that exsist at the short span but it will decrease the value. However, the moment will stay at positive zone .
Try to insulate the beam with same geometry and spacing and make a 2D design at the same software ..i think the results will be the same you got in 3D modeling.
Note : Please inform me if you got more logical explanation for this problem .
RE: "Positive" moments
The second span from the right on the first floor above grade shows a different behavior than all the rest. It appears there is an upward concentrated load applied right of midspan.
Check the sign of your load input. Positive loads are up. Negative loads are down.
BA