Section Modulus Of I Section Calculator For Steel

Section Modulus Formula for I-Section:

\[ S = \frac{b h^3 - b_w (h - 2 t)^3}{6 h} \]

Flange Width (b):

Height (h):

Web Width (b_w):

Flange Thickness (t):

Section Modulus (S):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Section Modulus?

The section modulus is a geometric property for a given cross-section used in the design of beams or flexural members. For an I-section, it represents the beam's resistance to bending, with higher values indicating greater strength.

2. How Does the Calculator Work?

The calculator uses the section modulus formula for I-sections:

\[ S = \frac{b h^3 - b_w (h - 2 t)^3}{6 h} \]

Where:

\( b \) — Flange width (mm)
\( h \) — Total height of the section (mm)
\( b_w \) — Web width (mm)
\( t \) — Flange thickness (mm)

Explanation: The formula accounts for the contribution of both flanges and the web to the section's bending resistance, subtracting the "missing" material in the web area.

3. Importance of Section Modulus

Details: Section modulus is crucial in structural engineering for determining a beam's capacity to resist bending moments. It's used to calculate maximum stresses and ensure structural safety.

4. Using the Calculator

Tips: Enter all dimensions in millimeters. Ensure flange width is greater than web width, and height is greater than twice the flange thickness for valid I-section geometry.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between elastic and plastic section modulus?
A: Elastic section modulus (calculated here) assumes linear stress distribution, while plastic modulus considers material yielding across the entire section.

Q2: How does section modulus relate to bending stress?
A: Bending stress = Bending Moment / Section Modulus. Higher section modulus means lower stress for a given moment.

Q3: What are typical section modulus values for standard I-beams?
A: Common I-beams (e.g., W-shapes) have section moduli ranging from about 100 cm³ to over 10,000 cm³ depending on size.

Q4: Can this formula be used for other shapes?
A: No, this specific formula is only for I-sections. Other shapes (rectangular, circular, etc.) have different formulas.

Q5: Why is the web subtracted in the calculation?
A: The formula effectively calculates the full rectangular section minus the weaker central portion, accounting for the I-section's efficient material distribution.