To solve the given problem (Question 1.10), we need to find the loads acting on Girder G2 and calculate the reactions at its simply supported ends. The following steps can be followed:

Step 1: Analyze the Loading on Girder G2

• Girder G2 supports beams S2 in the BC_24 zone.
• Beams S2 are spaced at 10 ft on center and span 40 ft with a total dead load of 80 psf for this zone (including slab, finishes, mechanical devices, etc.). There is also a live load of 50 psf.

Step 2: Calculate the Uniform Load Contribution

Each S2 beam spans 40 ft and is spaced at 10 ft, meaning that Girder G2 will experience a uniformly distributed load (UDL) transferred from each beam. This UDL can be calculated by multiplying the area load (psf) by the beam spacing.

For the dead load: $\text{UDL from dead load} = (\text{Dead Load per Area}) \times (\text{Spacing of S2}) = 80 \, \text{psf} \times 10 \, \text{ft} = 800 \, \text{lb/ft} = 0.8 \, \text{kips/ft}$

For the live load: $\text{UDL from live load} = (\text{Live Load per Area}) \times (\text{Spacing of S2}) = 50 \, \text{psf} \times 10 \, \text{ft} = 500 \, \text{lb/ft} = 0.5 \, \text{kips/ft}$

Thus, the total UDL (dead + live) on Girder G2 due to each S2 beam is: $\text{Total UDL} = 0.8 \, \text{kips/ft} + 0.5 \, \text{kips/ft} = 1.3 \, \text{kips/ft}$

Step 3: Reaction at Supports

Since Girder G2 is simply supported, we will calculate the reaction by summing the loads acting on the girder and dividing it equally between the two supports.

The length of Girder G2 is 40 ft (spanning from Grid 1 to Grid 3), and it supports 4 beams (S2).

The total load acting on Girder G2: $\text{Total Load} = \text{UDL per beam} \times \text{Number of beams} \times \text{Length of G2}$ $\text{Total Load} = 1.3 \, \text{kips/ft} \times 4 \, \text{beams} \times 40 \, \text{ft} = 208 \, \text{kips}$

The reaction at each support (since the girder is simply supported at both ends) is: $\text{Reaction} = \frac{\text{Total Load}}{2} = \frac{208 \, \text{kips}}{2} = 104 \, \text{kips}$

Final Answer:

The reaction at each support of Girder G2 is 104 kips.

Would you like further details on how the distributed load is calculated or explanations on other steps?

Related Questions:

1. What is the maximum moment in Girder G2 due to the applied loads?
2. How do we calculate the reactions for a continuous girder rather than a simply supported one?
3. What is the effect of considering the self-weight of Girder G2?
4. How would the reactions change if the span length of G2 were increased?
5. How do live loads affect the design of supporting beams and girders in structural framing?

Tip: Always check the boundary conditions (simple, fixed, continuous) when calculating reactions, as they significantly affect the results.