The section of a beam with hollow circle at its center for 6 m. Unit weight of concrete is 24 kN/m3 . Concrete compressive strength, f’c = 28 MPa and fct = 2.8 MPa. In this problem, b1 = 250 mm, b2 = 350 mm, h = 600 mm, and D = 150 mm.

1. Calculate the cracking moment of the beam.

a. 61.87 kN-m b. 54.80kN-m c. 58.93 kN-m d. 51.78 kN-m

2. Calculate the compressive stress in the beam due to this cracking moment.

a. 3.12 MPa b. 3.27 MPa c. 2.90 MPa d. 2.74 MPa

3. What additional weight can the beam support without cracking?

a. 9.85 kN/m b. 8.28 kN/m c. 7.61 kN/m d. 9.20 kN/m

 

 

b2 D b1- h