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How to Define Materials in ETABS

 Define materials


Step-01:Define Concrete Material.


Input Concrete Compressive Strength, i.e., 3000 psi,4000 psi, etc.


And Get the modulus of Elasticity, E to input in Etabs.



Also, Change the value here.



psi=lb/in2


Step-02:Define steel material


Define steel material according to this.


Just Change the Steel grade and get the other's value.

Now Input all values here,



 Download the Excel for free : 


https://drive.google.com/file/d/1lvxz17cyb1WrtQPTcqZsqY2XwecPsxdk/view?usp=sharing


📊 Load Combinations in ETABS According to BNBC – Complete Guide for Structural Engineers

Load combinations are essential in structural design to ensure safety under various loading scenarios. The Bangladesh National Building Code (BNBC) provides specific guidelines for combining different types of loads, such as dead load, live load, wind load, and seismic load.

In this guide, you’ll learn how to define and apply BNBC-based load combinations in ETABS.

📘 What Are Load Combinations?

A load combination is a formula that combines multiple loads acting on a structure simultaneously. It helps engineers design for the worst-case scenarios, considering strength, stability, and serviceability.

Example:

1.4 Dead Load (DL) + 1.6 Live Load (LL)

📐 Load Types Defined in BNBC

Load Type Description
DL Dead Load (self-weight, finishes)
LL Live Load (people, furniture, etc.)
WL Wind Load
EQX/EQY Earthquake Load in X/Y direction

📑 Common Load Combinations (BNBC 2020)

Here are typical load combinations based on BNBC 2020 (Chapter 2: Loads on Structures):

➤ Strength Design Load Combinations

  1. 1.4 DL

  2. 1.2 DL + 1.6 LL + 0.5 WL

  3. 1.2 DL + 1.6 LL + 0.5 EQX

  4. 1.2 DL + 1.6 LL + 0.5 EQY

  5. 1.2 DL + 1.0 WL + 1.0 LL

  6. 0.9 DL ± 1.0 WL

  7. 0.9 DL ± 1.0 EQX / EQY

⚠️ Note: Always verify these combinations with the latest BNBC version and the nature of your project (residential, commercial, industrial, etc.).

✅ How to Define Load Combinations in ETABS

Follow these steps:

🧱 Step 1: Go to Define → Load Combinations

  • Click "Add New Combo"

🧮 Step 2: Input a Name and Select Type

  • Example: COMBO_1

  • Type: Linear Add

➕ Step 3: Add Load Cases with Factors

  • Add each load (DL, LL, EQX, etc.)

  • Set the appropriate Load Factor based on BNBC

🔁 Repeat

Create multiple load combinations as per BNBC's prescribed formulas.

📌 Example in ETABS

Load Combination: 1.2 DL + 1.6 LL + 0.5 WL

Load Case Factor
DL 1.2
LL 1.6
WL 0.5

🧠 Best Practices

  • Use auto-load combinations in ETABS if supported for BNBC (or define manually).

  • Always include earthquake combinations if in seismic zones.

  • Label combinations clearly (e.g., COMBO_DL_LL_WL) for tracking.

  • Validate results using design codes for load-bearing checks.

🏁 Conclusion

Using the correct load combinations as per BNBC is essential for a safe and code-compliant structure. ETABS allows full flexibility in defining these combinations manually or through automated templates.