To solve the problem, we'll approach it step-by-step, starting by analyzing the entire frame and then focusing on individual members. The problem involves determining the reactions at the supports, the internal forces in certain members, and the bending moments at specific points.

Step 1: Analyze the entire structure for reactions

The structure is supported at points A (roller), B (pin), and C (pin). The roller at A can only provide a vertical reaction (Ay), while the pins at B and C can provide both vertical (By, Cy) and horizontal reactions (Bx, Cx).

The given loads include:

• A uniformly distributed load $w = 28 \, \text{kN/m}$ acting on member GH (spanning between G and H), with a span $c = 7.2 \, \text{m}$.
• A point load $P = 140 \, \text{kN}$.

Step 2: Calculate reactions at supports

We begin by calculating the reactions at supports. Since we have a statically determinate structure, we can use the equations of static equilibrium:

1. Sum of horizontal forces: $\sum F_x = 0 \implies B_x + C_x = 0$ Since the structure has no horizontal external loads, the horizontal reactions at B and C must cancel each other out, implying: $B_x = -C_x$

2. Sum of vertical forces: $\sum F_y = 0 \implies A_y + B_y + C_y = 28 \times 7.2 + 140$ Calculating the total vertical load: $28 \times 7.2 = 201.6 \, \text{kN} \quad \text{(total UDL)}$ Adding the point load: $201.6 + 140 = 341.6 \, \text{kN}$ Therefore: $A_y + B_y + C_y = 341.6 \, \text{kN}$

3. Sum of moments about point A: Taking moments about point A to eliminate $A_y$ (since its lever arm is zero): $\sum M_A = 0 \implies 7.2 \times C_y + 3.6 \times B_y - (28 \times 7.2) \times \frac{7.2}{2} - 140 \times (7.2 - 3.6) = 0$ Expanding: $7.2 \times C_y + 3.6 \times B_y - 28 \times 7.2 \times 3.6 - 140 \times 3.6 = 0$ Simplifying: $7.2 C_y + 3.6 B_y = 725.76 + 504$ $7.2 C_y + 3.6 B_y = 1229.76 \, \text{kN}$

   Dividing by 3.6: $2 C_y + B_y = 341.6$ Since we have $A_y + B_y + C_y = 341.6$: Substituting $C_y = 341.6 - B_y - A_y$: $2(341.6 - B_y - A_y) + B_y = 341.6$ Solving for $B_y$ and $C_y$:

   $C_y = B_y = 341.6/3 = 113.87 \, \text{kN}$

   Then $A_y = 113.87 \, \text{kN}$

Step 3: Analyzing Member GH for Bending Moments

• Bending moment at G (M_G): $M_G = 0 \, \text{kN m}$ as it's a pin support.

• Bending moment at H (M_H):

  = (28 \times 3.6 ) \times (3.6/2) = 181.44 \, \text{kN m}$$

Step 4: Axial Force in Member BF (F_BF)

To find $F_{BF}$, use method of sections and vertical equilibrium of the left side. $F_{BF} = 113.87 -$ reaction = 113.87 kN.

Step 5: Bending Moment in Member DF at E (M_E)

This requires section D,E,F diagram.

Would you like me to go over it with each reaction?