anyone know how to solve this?? I am doing this to have column reaction to have wind load but it shows me this warning and my Fx and Fy are both 0 KN. Thanks
When you encounter the warnings in ETABS stating that “THE STRUCTURE HAS NO (UNDERSTAND) MASS; NO EIGEN MODES CAN BE FOUND” and “NO EIGEN MODES CAN BE FOUND,” it indicates that the software is unable to compute the dynamic properties of your structure due to a lack of defined mass. This situation typically arises when performing modal analysis or when trying to apply loads that depend on the dynamic response of the structure, such as wind loads.
Ensure that all structural elements (beams, columns, slabs) have mass assigned to them. In ETABS, mass can be defined through:
The Mass Source settings under the “Define” menu.
Assigning a Uniform Load or Area Load which contributes to the mass.
f your model includes floor slabs, you can use automatic mass generation features:
Go to Define > Mass > Automatic and ensure that it is enabled for your floors.
Ensure that load combinations include dead loads (DL) or other loads that contribute to mass. If only live loads are defined without any dead load, it may lead to zero effective mass.
Check if all structural elements are properly connected. Gaps or unconnected nodes can lead to issues in defining an effective mass.
Make sure each element has appropriate material properties assigned, as missing material definitions can also affect mass calculations.
Confirm that you are using a suitable analysis type for your model:
For wind load analysis, ensure you have selected a linear static or dynamic analysis method depending on your design requirements.
If performing modal analysis, ensure that you have set up eigenvalue analysis correctly under Analysis settings.
After making these adjustments:
Save your model.
Rerun the analysis by clicking on Run Analysis.
Monitor the output messages for any further warnings or errors.
Once the analysis completes successfully:
Check if column reactions (Fx and Fy) now show non-zero values.
Review modal results if applicable; ensure eigen modes are computed without warnings.
If after following these steps you still encounter issues, consider reviewing ETABS documentation or reaching out to technical support for further assistance specific to your model configuration.
