I have a building that is on a radius (basically a rectangle that is curved to approximately 442' radius). It is a 3-story building with concrete floors and a membrane roof (so I am assuming rigid floor diaphragms and a semi-rigid roof diaphragm). I have it all modeled without any error or warnings. The gravity runs fine. But when I run the lateral design, I run into issues. The lateral load is applied to the Global X and Y axis, which is putting my lateral beams and columns into minor axis bending since the frames are not oriented parallel to the global X and Y axis. Is there a way to get the lateral loads to be applied to the local axis of the frames so the load is applied in the in-plane direction of the frames? Any help is appreciated.
Jeff
Program generated wind and seismic loads are generated based on the global X and Y axes. While some angled loads are also applied to take care of things like seismic orthogonal effects or wind eccentricity, there is not a simple override to change the principal lateral load direction. I'll make sure such an enhancement request is logged.
Meanwhile, your best bet is to run the lateral analysis for the X and Y directions normally and print out the Loads and Applied Forces report. That report includes information like total seismic forces per floor, location of the center of mass, and for wind loads the total pressure. From there it should be fairly easy to establish your own User Defined Story forces which can be applied at any angle (load angles are measured in degrees counter clock-wise from the positive X axis).
For more see various load related topics under Ram Frame: communities.bentley.com/.../ram-structural-system-ram-frame
Answer Verified By: Jeffrey Champlin