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Plastic Moment for SSB with UDL Calculator

Plastic Moment Formula:

\[ M_{p,udl} = \frac{W_u \times l}{8} \]

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1. What is Plastic Moment for SSB with UDL?

Definition: This calculator computes the plastic moment capacity of a simply supported beam (SSB) under a uniformly distributed load (UDL).

Purpose: It helps structural engineers determine the maximum moment capacity before plastic deformation occurs.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ M_{p,udl} = \frac{W_u \times l}{8} \]

Where:

  • \( M_{p,udl} \) — Plastic moment (capacity)
  • \( W_u \) — Theoretical or nominal load
  • \( l \) — Overall length of the beam

Explanation: The plastic moment is calculated by multiplying the load by the beam length and dividing by 8.

3. Importance of Plastic Moment Calculation

Details: Proper plastic moment estimation ensures structural integrity and safety against plastic collapse.

4. Using the Calculator

Tips: Enter the theoretical load and beam length (both with ±5% tolerance). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a plastic moment?
A: The plastic moment is the maximum moment a beam can resist before plastic hinges form.

Q2: Why divide by 8 in the formula?
A: For a simply supported beam with UDL, the maximum moment occurs at midspan and equals wL²/8.

Q3: What units should I use?
A: Consistent units must be used (e.g., kN and meters, or kips and feet).

Q4: How does UDL differ from point loads?
A: UDL is distributed along the beam length, while point loads act at specific locations.

Q5: What safety factors should be considered?
A: Always apply appropriate safety factors per relevant design codes.

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