RISA-3D Moment reaction is double the member moment at the base 3

[EngDM]

I have a simple cantilevered column system, and the node reactions spreadsheet is showing an MZ of 282 kN-m. When I go into the detailed report for that member, the moment is 141kN-m. I can't for the life of me figure out why this would be doubled. The support is fully fixed against rotation and translation.

EDIT: Mods please delete this thread I am big dumb and duplicated the member over itself with the loads.

 

[STpipe]

Can you post screenshots as I'm not familiar with Risa. I guess which results makes sense? With a cantilevered column system, it should be possible to back check what moment value you would expect. Do you see the same discrepancy with the shear results?

 

[EngDM]

Can you post screenshots as I'm not familiar with Risa. I guess which results makes sense? With a cantilevered column system, it should be possible to back check what moment value you would expect. Do you see the same discrepancy with the shear results?

Refer to edited original post

 

[DaveAtkins]

I am big dumb

I don't call that big dumb - I call that being persistent and finding your own mistake!

 

[STpipe]

Refer to edited original post

That's what I initially suspected. Glad you figured it out!

 

[Eng16080]

I am big dumb

Count me in. I've done this before! Glad you solved it. I recall also struggling to solve this sort of error.

 

[ghostdigital]

I have a simple cantilevered column system, and the node reactions spreadsheet is showing an MZ of 282 kN-m. When I go into the detailed report for that member, the moment is 141kN-m. I can't for the life of me figure out why this would be doubled. The support is fully fixed against rotation and translation.

EDIT: Mods please delete this thread I am big dumb and duplicated the member over itself with the loads.

I've done worse... so, there I've one upped you.

 

[Eng16080]

I wish I could remember all the details now, but I heard a story of an engineer who built a full 3D model of a multistory building, designed all the members, and created framing plans . . . without realizing that he was using length units of feet instead of meters. He was a recent grad and had no idea that every member was significantly undersized. Luckily somebody reviewed the plans and caught the mistake!

 

[STpipe]

Yikes, that's frightening! Perhaps not the wisest move to let the new grad build a complicated full 3D model without progressively building up to that experience.

Happens to all of us. Last week I got slightly distracted and forgot to multiply the seismic response coefficient to the seismic weight when designing a temporary braced tower, so I ended up applying the full seismic weight as a lateral load . I spent way too much time getting the design to work until I decided to revisit my assumptions and that's where I caught my error.

 

[DaveAtkins]

It is so important to be able to take a step back, ignore the numbers, and say, "does this make sense?" I suspect that is what you did, STpipe.

This only comes with experience, of course, so early in your career it is vital to have someone reviewing your work. Actually, at my company, nothing goes out without being reviewed, no matter how experienced the originator of the design.