Why is the bending moment due to DL and tendon secondary not as expected? 

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Answer:

Following issues were noted:
1) The node local axis weren't properly defined.

2) The tendon definition was improper. It was noted that reference type was taken as element. However, in that case the tendon length and hence the losses due to curvature won't be correctly estimated as mentioned in the help manual. It is recommended to use the "Straight" reference axis in case of such structures with high degree of curvature..


3) Tendon profiles are not lying within the section. Kindly refer the image below.


Also, it is recommended to use the Round option while defining the tendon profile instead of Spline option if the change in slope of tendon is not very large. Generally the tendon coordinates as used in India are satisfied by definition as Round and spline might result in different tendon profile than actually expected.