How to Define Mass Source in ETABS

 Mass Source

According to BNBC-2020: (Page-3209)

The mass source will be applicable like this:

All Dead load will participate 100%. Hence, the multiplier will be 1.

All Dead Loads = 1

Live Load = 0.25 (If LL<=3kn/m2)

Live Load= 0.5 (If LL>3kn/m2)

What is a Mass Source?

A mass source in ETABS is a concentrated mass representing a particular structure component. It is used to model the masses of various elements, such as walls, floors, columns, or any other components that contribute significantly to the overall mass distribution of the structure. Properly defining mass sources ensures that the structural analysis considers the correct mass distribution for accurate results.

Step-by-Step Guide to Define Mass Source in ETABS

To define a mass source in ETABS, follow these steps:

1. Launch ETABS Software: Open the ETABS software on your computer.
2. Create or Open Model: Create a new model or open an existing model in ETABS to which you want to add a mass source.
3. Access "Define Mass Source": In the ETABS interface, go to the "Define" menu, then click on "Mass Source."
4. Add New Mass Source: Once the "Mass Source Manager" window appears, click on the "New" button to create a new mass source.
5. Define Mass Source Properties: In the "Mass Source Data" window, you will have the following options:

• Name: Provide a descriptive name for the mass source (e.g., Floor Mass, Wall Mass).
• Location: Specify the location of the mass source by selecting joints or points in the model.
• X, Y, Z Coordinates: Define the mass source's X, Y, and Z coordinates relative to the global coordinate system.
• Mass: Enter the value of the mass associated with the mass source.
• Mass Moment of Inertia: If applicable, provide the values of the mass moment of inertia in the X, Y, and Z directions.

1. Assign Mass Source to Elements: After defining the mass source properties, click "Assign Objects" to associate the mass source with specific structural elements. Select the relevant elements (walls, floors, etc.) to which you want to apply the mass source.
2. Save and Analyze: Save the model to retain the defined mass sources. Proceed with the structural analysis to observe the effects of the mass distribution on the structure's behavior.

Tips for Defining Mass Sources

1. Accuracy and Realism: Ensure that the mass sources accurately represent the actual mass distribution in the structure for reliable analysis results.
2. Use Meaningful Names: Give meaningful names to mass sources to quickly identify and manage them within the model.
3. Consistency: Be consistent in defining the mass units (e.g., kilograms, pounds) throughout the model.
4. Verify Mass Values: Double-check the mass values entered for each mass source to avoid errors in the analysis.
5. 
   

Conclusion

Defining mass sources in ETABS is critical in structural analysis, especially for dynamic loading scenarios. By correctly representing the mass distribution of the structure, engineers can obtain more accurate results and make informed decisions during the design process. Follow the step-by-step guide in this article to define mass sources effectively and optimize your structural analysis in ETABS.