Building tiedown negative value

[Henry94606]

In calculate shearwall I had a long SW that resulted in tiedown value as negative.
How should I understand this in layman terms ?
After reduce the length of the SW, I had it a positive number. Wonder if at certain lengths, SW starts to yield negative tiedown value.

 

[Celt83]

For any calculation step 1: establish a sign convention, this will allow you to differentiate tension and compression so you can understand physically what signed numbers indicate.

 

[TRAK.Structural]

The aspect ratio, gravity loads, and the lateral force will determine the net uplift at the tension side of a shear wall. It is certainly possible for a shear wall to have no net uplift reaction.

 

[Harbringer80]

In calculate shearwall I had a long SW that resulted in tiedown value as negative.

That means the end wall post is in net compression.

How should I understand this in layman terms ?
After reduce the length of the SW, I had it a positive number.

Net tension therefore a holdown is required.

Wonder if at certain lengths, SW starts to yield negative tiedown value.

I'd encourage you to draw a free body diagram and run a handcalc on the shear wall for overturning. This will help you better understand the software output.

 

[driftLimiter]

All that we know for sure is if all the statics is done correctly, and the free body diagram is correct, then the force is opposite of the assumed direction of the chord force.

In layman's terms, its opposite of what you thought.

Thats about all the layman should understand about this because its based on FBD, statics, etc and this isn't for the layman.

If you have assumed the tiedown load is a net tension at the base of the chord, and it comes out negative it suggests that you have a net downward load and no tension. This can only happen in the presence of dead loading, because a shear wall with no gravity load will always have equal and opposite chord forces.

Harbinger's advice to sketch and solve a proper FBD should give you all the understanding needed to interpret the result.