I am modelling a precast RC piperack with footing foundations. I've used the foundation support type, specifically the plate mat command. I have tried the following commands, effectively stacking the support conditions.
SUPPORTS5364 TO 5415 5420 TO 5435 5462 TO 5473 PLATE MAT DIRECT YONLY SUBGRADE 480005364 TO 5415 5420 TO 5435 5462 TO 5473 PLATE MAT DIRECT XONLY SUBGRADE 336005364 TO 5415 5420 TO 5435 5462 TO 5473 PLATE MAT DIRECT ZONLY SUBGRADE 33600
I am finding this does not allow rotation of the footings about the vertical Y axis so, therefore, locks in high torsion moments in the columns.
Any suggestions on how to allow rotation about the vertical axis?
You may avoid the torsion at the columns by assigning the MX member releases at the base of the column.
Thanks but I think this is a real effect. I've isolated the foundations in a separate model and applied large MY moments. The foundations do rotate so I think it's a problem with the horizontal spring values I'm using.