Rotational Moment Of Inertia Calculator I Beam

Rotational Moment of Inertia Formula for I-beam:

\[ I = \frac{b h^3 - b_i h_i^3}{12} \]

Flange Width (b):

Height (h):

Web Width (b_i):

Web Height (h_i):

Rotational Moment of Inertia (I):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Rotational Moment of Inertia for I-beam?

The rotational moment of inertia (I) for an I-beam is a measure of its resistance to bending about a particular axis. It's a crucial parameter in structural engineering that determines how the beam will deflect under load.

2. How Does the Calculator Work?

The calculator uses the standard formula for I-beam moment of inertia:

\[ I = \frac{b h^3 - b_i h_i^3}{12} \]

Where:

\( b \) — Flange width (m)
\( h \) — Total height of the I-beam (m)
\( b_i \) — Web width (m)
\( h_i \) — Web height (m)
\( I \) — Moment of inertia (kg·m²)

Explanation: The formula calculates the moment of inertia by subtracting the "missing" rectangular area (the web) from the overall rectangular area.

3. Importance of I-beam Moment of Inertia

Details: The moment of inertia is fundamental in structural analysis as it determines the beam's stiffness and its ability to resist bending. Higher values indicate greater resistance to bending.

4. Using the Calculator

Tips: Enter all dimensions in meters. Ensure flange width (b) is greater than web width (b_i) and total height (h) is greater than web height (h_i) for valid I-beam geometry.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between I-beam and H-beam?
A: I-beams have tapered flanges while H-beams have parallel flanges. The calculation method is similar but dimensions differ.

Q2: How does moment of inertia affect beam performance?
A: Higher moment of inertia means less deflection under load and greater load-bearing capacity.

Q3: Can this formula be used for other beam shapes?
A: No, this specific formula is only for I-beams. Other shapes like rectangular or circular beams have different formulas.

Q4: Why is the web subtracted in the formula?
A: The formula calculates the moment of inertia by treating the I-beam as a solid rectangle minus the "missing" web portion.

Q5: What are typical values for I-beam moment of inertia?
A: Values vary widely based on size, but common steel I-beams range from 10⁻⁶ to 10⁻² m⁴ depending on dimensions.