7.2. Example 7-2: Semi-Circular Arch

Try these first

1. 1.

   What is the shape of a semi-circular arch?

   Hint

   Think about the shape of the letter 'C' but closed on one side.

2. 2.

   What type of loading do we consider for a semi-circular arch?

   Hint

   It’s the same type of loading that you might find on a flat roof.

3. 3.

   What shape is formed by a semi-circular arch?

   • Square
   • Triangle
   • Half Circle
   • Quarter Circle

   Hint

   Think of the letter 'C'.

4. 4.

   True or False: A semi-circular arch can only support vertical loads.

   • True
   • False

   Hint

   Consider how loads can act from different angles.

5. 5.

   If a 30-foot span semi-circular arch is subjected to a total vertical load of 20 kips, calculate the vertical reaction at the supports.

   Hint

   How many supports does the arch have?

6. 6.

   Determine the horizontal reaction at the base of a semi-circular arch with an increased height of 15 feet due to external loads acting off the centroid.

   Hint

   Consider how the change in height alters the angle of the loading.