Beam Design
Reinforced concrete beams are designed to resist bending and shear forces. The design is based on the ultimate strength method, where the nominal strength must exceed factored loads. The flexural strength (Mn) depends on the area of tension steel (As), yield strength (fy), concrete strength (f'c), and section geometry. Shear design requires stirrups to resist diagonal tension. The balanced reinforcement ratio (ρ_balanced) represents the transition between tension-controlled and compression-controlled failure.
Knowledge Check
1.A rectangular beam has width b = 300 mm, effective depth d = 500 mm, As = 2,000 mm², fy = 420 MPa, and f'c = 30 MPa. What is the depth of the compression block (a)?
2.What is the formula for the nominal flexural strength (Mn) of a singly reinforced rectangular beam?
3.The balanced reinforcement ratio (ρ_balanced) occurs when:
4.A beam has a factored moment (Mu) of 200 kN·m. The nominal moment capacity (Mn) must be at least: (Assume φ = 0.9)
5.What is the minimum area of steel required for temperature and shrinkage reinforcement in a slab?
6.In ACI 318, the strength reduction factor (φ) for flexure in a tension-controlled section is:
7.The nominal shear strength (Vc) provided by concrete in a beam is approximately:
8.A rectangular beam has As = 1,800 mm², fy = 420 MPa, d = 550 mm, and a = 80 mm. What is the nominal moment capacity (Mn)?
9.What is the purpose of shear stirrups in a reinforced concrete beam?
10.The maximum spacing of shear stirrups in a beam is limited to: