Horizontal Beams showing zero axial force when they should have non-zero value on application of lateral force on 2D Frame

Question:

I am modelling simple 2D frames for the purpose of analysing their structural response from Unit Lateral Load loads applied at the top of Frame. I have kept all connections as pinned to compare the interal forces with those from hand calculations. However, the horizontal members which have been modelled as beams in the frame are showing zero axial force (Fx) when there should be non-zero axial forces in the beams. Why is this so?
All members have been modelled as Beam elements

Answer:

Hi,

The zero axial forces in the horizontal members are caused by the story diaphragm. If you change it from 'Consider' to 'Do not consider', you can see non-zero axial forces. 

Regards,
DK Lee
Creation date: 8/2/2018 12:16 PM      Updated: 8/2/2018 9:47 PM
Files   
Axial Force.PNG
39 KB
Axial Force[1].PNG
54 KB
DataImage2.png
45 KB
DataImage27.png
28 KB
DataImage71.png
19 KB
DataImage76.png
150 KB
Leadenhall South Frame Original (On Site Sections) RIGID Connections.mgb
104 KB
Leadenhall South Frame Original (On Site Sections).mgb
101 KB
Model.PNG
25 KB