| layout | default |
|---|---|
| title | MEE342 Bridge Design 2026 |
You will design a lightweight pedestrian bridge and verify it using ANSYS.
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Element types: Frame: BEAM188 only, Deck: SHELL181 only
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Deck geometry: Span: 15.0m, Deck width: 3.0m, Deck thickness: 8mm
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Deck mesh element size: 0.25m across the deck
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The deck must be a complete shell surface covering the entire 15.0m × 3.0m footprint (no gaps/holes).
You must provide beams that actually support the deck. Most real bridges use interior support lines. You are encouraged to include beams that support the deck area. When connecting beams and the deck, use shared nodes, do not use contacts.
- Create the deck shell surface.
- Mesh the deck first (0.25m size).
- Create your beam lines directly on the deck surface (beam centerlines lie in the same plane as the deck midsurface).
- Mesh the beams so beam nodes coincide with deck shell nodes along the support lines.
If two beams meet or cross, they must be connected:
- Ensure beam lines intersect and the mesh creates a shared node at the intersection.
- Model joints as fully connected (rigid/continuous) joints by default.
No special bolt/weld/pin flexibility modeling is required.
Minimize total mass of the entire bridge (beams + deck).
Use global axes with +Z upward.
- Gravity (self-weight): ON
- Uniform pedestrian pressure: $ q = 5.0\ \text{kN/m}^2 \quad \text{downward (−Z)} $
- Fatigue load cycle: Use "zero-based loading" (between 0 and +q). Use equivalent stress as the "stress component" for life and safety factor calculation. Target is infinite life (
$10^6$ cycles). Use fatigue strength factor (Kf) of 0.7.
Use simply supported conditions:
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Left support (pin): constrain
$U_x = U_y = U_z = 0$ at the left abutment end region. -
Right support (roller): constrain
$U_y = U_z = 0$ .
Apply constraints to a small set of end nodes/area—not a single node.
Use the default structural steel in ANSYS.
Your design must satisfy all of the following:
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Strength (static): The maximum Von Mises stress must be no larger than 160MPa:
$\sigma_{vM,\max} \le 160\ \text{MPa}$ -
Deflection (static): The maximum deflection of the deck must be no larger than 37.5mm along Z-direction:
$\delta_{\max} \le \frac{L}{400} = 37.5\ \text{mm}$ -
Vibration (modal): The 1st natural frequency must be greater than 3Hz:
$f_{1,\text{vertical}} \ge 3.0\ \text{Hz}$ - Fatigue: Fatigue factor of safety greater than 2.0.
- A screenshot showing full deck shell coverage and 0.25 m mesh.
- Results table: mass,
$\sigma_{vM,\max}$ ,$\delta_{\max}$ ,$f_{1,\text{vertical}}$ , fatigue factor of safety. - One plot of deformed shape, one plot of static factor of safety, and one plot of fatigue factor of safety.