Hollow Circular Beam with Known Cracking Moment
Situation
A concrete beam with cross section in Figure CO4-2B is simply supported over a span of 4 m. The cracking moment of the beam is 75 kN·m.
1. Find the maximum uniform load that the beam can carry without causing the concrete to crack, in kN/m.
| A. 35.2 | C. 33.3 |
| B. 37.5 | D. 41.8 |
2. Find the modulus of rapture of the concrete used in the beam.
| A. 4.12 MPa | C. 3.77 MPa |
| B. 3.25 MPa | D. 3.54 MPa |
3. If the hallow portion is replaced with a square section of side 300 mm, what is the cracking moment of the new section in kN·m?
| A. 71.51 | C. 78.69 |
| B. 76.58 | D. 81.11 |
A 12-inches square steel bearing plate lies between an 8-inches diameter wooden post and a concrete footing as shown in Fig. P-110. Determine the maximum value of the load P if the stress in wood is limited to 1800 psi and that in concrete to 650 psi.