added ansys bridge design activity

Author: antantantant

mee342_bridge_design.md

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+---
+layout: default
+title: MEE342 Bridge Design 2026
+---
+
+# ANSYS Bridge Design Activity 2026
+
+You will design a lightweight pedestrian bridge and verify it using **1 static** and **1 modal** analysis in ANSYS.
+
+---
+
+## 1. Model setup
+
+### Element types
+- **Primary structure (truss/frame/bracing):** **BEAM188 only**
+- **Deck:** **SHELL181 only**
+
+### Deck geometry
+- **Span:** 15.0 m  
+- **Clear deck width:** 3.0 m  
+- **Deck thickness:** **8 mm steel**
+
+### Deck mesh
+- Shell element size: **0.25 m** across the deck
+
+### Deck must be fully covered
+- The deck must be a **complete shell surface** covering the entire **15.0 m × 3.0 m** footprint (**no gaps/holes**).
+
+---
+
+## 2. Deck support and beam–deck connection
+
+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 **central deck area**. When connecting beams and the deck, **use shared nodes (conformal connection), do not use contacts.**
+
+### How to do it
+1. Create the deck shell surface (15.0 m × 3.0 m).
+2. **Mesh the deck first** (0.25 m size).
+3. Create your beam lines directly on the deck surface (beam centerlines lie in the same plane as the deck midsurface).
+4. Mesh the beams so **beam nodes coincide with deck shell nodes** along the support lines.
+
+---
+
+## 3. Beam-to-beam joints
+
+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.
+
+---
+
+## 4. Design objective
+
+**Minimize total mass** of the entire bridge (beams + deck).
+
+---
+
+## 5. Loads (apply to the deck shell top face)
+
+Use global axes with **+Z upward**.
+
+- **Gravity (self-weight): ON**
+- **Uniform pedestrian pressure:**
+  \[
+  q = 5.0\ \text{kN/m}^2 \quad \text{downward (−Z)}
+  \]
+
+---
+
+## 6. Boundary conditions (supports)
+
+Use **simply supported** conditions:
+
+- **Left support (pin):** constrain \(U_x = U_y = U_z = 0\) at the left abutment end region.
+- **Right support (roller):** constrain \(U_y = U_z = 0\), allow \(U_x\).
+
+> Apply constraints to a small set of end nodes/area—not a single node.
+
+---
+
+## 7. Material + performance limits (steel-only)
+
+Assume **S275 steel**, yield strength \(f_y = 275\ \text{MPa}\).
+
+Your design must satisfy all of the following:
+
+1. **Strength (static):**
+
+The maximum Von Mises stress must be no larger than 160MPa:
+   \[
+   \sigma_{vM,\max} \le 160\ \text{MPa}
+   \]
+
+2. **Deflection (static):**
+
+The maximum deflection of the deck must be no larger than 37.5mm along Z-direction:
+   \[
+   \delta_{\max} \le \frac{L}{400} = 37.5\ \text{mm}
+   \]
+
+3. **Vibration (modal):**
+
+The 1st natural frequency must be greater than 3Hz:
+   \[
+   f_{1,\text{vertical}} \ge 3.0\ \text{Hz}
+   \]
+
+---
+
+## 8. What to submit
+
+- A screenshot showing **full deck shell coverage** and **0.25 m mesh**.
+- Results table: **mass**, \(\sigma_{vM,\max}\), \(\delta_{\max}\), \(f_{1,\text{vertical}}\).
+- One plot of **deformed shape** and one plot of **von Mises stress**.
+- The standard model file (.stp) exported from ANSYS EnSight.