According to EN 1998-1:2004 188.8.131.52 (11), the seismic excitation must be applied to all relevant directions.
For some structures there might be more than 2 relevant directions, and these directions may deviate from the directions of the global X- and Y-direction in the Robot model.
In my understanding of Robot, this should be possible when using the button "direction definition" in the "EN 1998 Parameters" dialog box.
I have tried this to a simple model, but it does not seem to work properly.
Have anyone tried something similar, with good results?
Keep in mind that unlike Newmark combination rule, SRSS rule is not direction dependant.
Rotating the building + newmark rule i guess will do the job.
....just to clarify,.... According to EC8 all the structure's members should "resist" 100% of the prescribed seismic forces in one direction plus 30% of the prescribed forces in the perpendicular direction!
when Z direction is disregarded.
So, what I need to check in the "Direction definition" is......
Am I wrong?