Difference between lumped mass and permanent load

[Mohamed Meshaly]

Hi all
Do anyone knows the difference between the lumped mass on a joint and a vertical load (permanent load) on a joint? I do know that I have the option to input the vertical permanent gravity loads or input it as an additional mass/length in the SECTIONS part. But after entering the vertical loads on the joints, Do I also have to enter a lumped mass at each joint with the same value of the vertical load in Mx, My, Mz ?

Thanks a lot

[seismosoft]

Yes, force and mass are two different things, hence, if you are running eigenvalue/dynamic analyses, defining vertical loads will not suffice and you will need to define masses as well.

Alternatively, you may do the opposite, i.e., define mass and then select the option, in the Settings, to transform mass into loads.

In addition, as we repeatedly state in this Forum, whenever you have doubts of this type, you can run some simple trial analyses, changing the input parameters and inspecting the corresponding results - this should provide with the answers you need for the majority of cases.

Finally, we note that, judging from your three recent posts, we suspect that you could benefit from a careful and thorough reading of the Help System, User Manual, Verification Report, and past Forum posts.

Seismosoft Support