Shear Moment Curves
1. **Problem 1: Shear and Moment Diagrams for a Simply Supported Beam with Uniform Load**
Given: A simply supported beam of length $L=12$ m with a uniform distributed load $w=9$ kN/m over the entire length.
2. **Formulas and Rules:**
- Reactions at supports for uniform load: $R_A = R_B = \frac{wL}{2}$
- Shear force at a distance $x$ from the left support: $V(x) = R_A - wx$
- Bending moment at a distance $x$: $M(x) = R_A x - \frac{w x^2}{2}$
- Maximum moment occurs at mid-span $x=\frac{L}{2}$
3. **Calculations:**
- Calculate reactions:
$$R_A = R_B = \frac{9 \times 12}{2} = 54\text{ kN}$$
- Shear force at $x=0$: $V(0) = 54$ kN
- Shear force at $x=6$ m (mid-span):
$$V(6) = 54 - 9 \times 6 = 54 - 54 = 0$$
- Shear force at $x=12$ m: $V(12) = 54 - 9 \times 12 = 54 - 108 = -54$ kN
- Bending moment at mid-span:
$$M(6) = 54 \times 6 - \frac{9 \times 6^2}{2} = 324 - 162 = 162\text{ kN}\cdot\text{m}$$
4. **Interpretation:**
- Shear diagram is a straight line decreasing from $+54$ kN at left support to $-54$ kN at right support.
- Moment diagram is a parabola with maximum $162$ kN·m at mid-span.
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5. **Problem 2: Shear and Moment Diagrams for Beam with Concentrated Loads and Uniform Load**
Given: Beam with point loads $P_1=36$ kips, $P_2=24$ kips, and uniform load $w=12$ kips/ft over last segment.
6. **Approach:**
- Calculate support reactions using equilibrium equations.
- Construct shear diagram by adding/subtracting loads stepwise.
- Calculate bending moments by integrating shear or using moment equations.
(Due to complexity, detailed numeric steps omitted here for brevity.)
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7. **Problem 3: Shear and Moment Diagrams for Combined Footing with Uniform Soil Pressure**
Given: Footing length $27'$ with uniform soil pressure $w=24$ kips/ft.
8. **Approach:**
- Treat footing as beam with uniform distributed load.
- Calculate reactions at supports (columns).
- Use formulas for shear and moment as in Problem 1.
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9. **Problem 4: Shear and Moment Diagrams for Combined Footing with Trapezoidal Soil Pressure**
Given: Trapezoidal distributed load varying from $2$ to $8$ kips/ft over $20'$ length.
10. **Approach:**
- Calculate equivalent loads and their positions.
- Calculate reactions using equilibrium.
- Construct shear and moment diagrams accordingly.
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11. **Problem 5: Shear and Moment Diagrams for Compound Beam with Mixed Loads**
Given: Uniform loads, point loads, and supports at various points.
12. **Approach:**
- Calculate reactions at supports using equilibrium.
- Construct shear diagram by adding/subtracting loads.
- Calculate bending moments at key points.
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13. **Problem 6: Shear and Moment Diagrams for Simply Supported Beam with Uniform Load**
Given: Beam length $12$ ft with uniform load $2$ k/ft.
14. **Calculations:**
- Reactions:
$$R_A = R_B = \frac{2 \times 12}{2} = 12\text{ kips}$$
- Shear at $x=0$: $V(0) = 12$ kips
- Shear at mid-span $x=6$ ft:
$$V(6) = 12 - 2 \times 6 = 0$$
- Shear at $x=12$ ft: $V(12) = 12 - 24 = -12$ kips
- Moment at mid-span:
$$M(6) = 12 \times 6 - \frac{2 \times 6^2}{2} = 72 - 36 = 36\text{ kips}\cdot\text{ft}$$
15. **Summary:**
- Shear diagram is linear from $+12$ to $-12$ kips.
- Moment diagram is parabolic with max $36$ kips·ft at mid-span.