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Drift Check for Earthquake in Excel

 Drift Check for Earthquake 


Drift Check for Earthquake








Input all values in Yellow Color.


Find EQx and EQy


 Paste the value in Excel.

🏗️ Earthquake-Induced Story Drift Check Using Excel

In structural engineering, story drift refers to the lateral displacement of one level of a building relative to the level below, primarily caused by lateral forces such as earthquakes. Controlling story drift is crucial to ensure the structural integrity and serviceability of buildings, preventing damage to non-structural elements and discomfort to occupants.

📘 Understanding Story Drift in Seismic Design

Story drift is calculated as the difference in lateral displacement between two consecutive floors. It is typically expressed as a ratio by dividing the drift by the story height. Building codes, such as the Bangladesh National Building Code (BNBC) 2020, provide guidelines for acceptable story drift limits to ensure safety and comfort.

According to BNBC 2020:(ResearchGate)

  • For structures with a fundamental period (T) less than 0.7 seconds: Maximum allowable story drift is 0.025 times the story height.

  • For structures with T equal to or greater than 0.7 seconds: Maximum allowable story drift is 0.020 times the story height.(Scribd)

These limits help prevent excessive deformation during seismic events, ensuring the building's structural integrity.

🧪 Performing Story Drift Analysis Using ETABS and Excel

To assess story drift due to earthquake loads:

  1. Model the Structure in ETABS:

  2. Run the Analysis:

    • Perform the analysis to obtain displacement results.

  3. Extract Displacement Data:

    • Navigate to Display → Show Tables → Analysis Results → Displacements → Story Max/Avg Drift.

    • Select the relevant seismic load cases (e.g., EQx, EQy).

    • Copy the maximum drift data for each story.

  4. Use Excel for Drift Calculation:

    • Paste the extracted data into an Excel spreadsheet.

    • Calculate the story drift ratio by dividing the drift by the corresponding story height.

    • Compare the calculated drift ratios with the allowable limits as per BNBC 2020 to assess compliance.

📥 Download Story Drift Check Excel Template

For a practical application, you can download a pre-formatted Excel template to perform story drift checks:

👉 Download Excel

📚 Further Reading