Load to mass conversion: mass and conversion directions
Accepted solution
Hi @Anonymous
Conversion direction: it is to decide which load defined in a selected load case should be treated as masses. By default it is -Z which means that all vertical loads acting downwards (e.g. weight of some piece of equipment or machinery bolted to a floor) is treated as active mass for seismic analysis. If you set it as e.g. X+ you could convert wind load but I don't think you actually need this 
Mass direction: allowable direction of vibrations e.g. you may exclude vertical; vibrations (of floors) while analysis a multi-story building with rigid floor systems or horizontal ones for a single slab (footfall analysis).
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Artur Kosakowski
Thank you very much for your explanation, so how Mass Direction in Load to Mass Conversion tab relate to Active mass direction in Modal Analysis Parameter table ?
Hi @Anonymous
This is the same definition
In most of the situation you first decide which directions of the vibrations you want to consider defining the modal analysis and then you mark the same check boxes for the load to mass conversion unless you want to perform e.g. some comparison tests and e.g. unmark Z or (X and Y) in the modal analysis (or create a new modal case with such settings) to see the difference with all 3 marked.
If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.
Artur Kosakowski
Hi @Anonymous
I just wanted to check if you still need any additional clarification on the mass directions.
Artur Kosakowski
