Using latest ACI 318 and ACI 440. IR, solve the beam problem below. Compare the two designs in 8 x 3 format. The eight steps for the ACI 44(). IR are provided for your reference. Comment on each step in the last column.

A simply supported normal weight concrete beam with compressive strength = 3500 psi is needed in a medical facility to support MRI unit. The beam is an interior beam. The beam is to be designed to carry a service live load of 325 lb/ft (13% sustained) and a superimposed service dead load of 195 lb/ft over a span of 9 ft. The beam deflection should not exceed 1/240, which is the limitation for long-term deflection. Due to construction restriction, the depth of the member should not exceed 12 in. GFRP reinforcing bars are selected to reinforce the beam; material properties of the bars are shown in table below.

Tensile Strength;	90,000 psi	620.6 MPa
	0.014	0.014
Ef	6,500,000 psi	44,800 MPa

Flexural Design of FRP Strengthened RC Beam

A simply supported exterior rectangular (16" by 10") reinforced concrete beam is reinforced with 3 # 8 rebars. The flexural reinforcement is placed 2.5 inches from the bottom of the beam. The concrete strength is 4000 psi and the steel yield stress is 60,000 psi. The shear reinforcement is #4 stirrups spaced according to minimum requirements. The ultimate moment is 0.9 times the nominal capacity of the beam (using ACI 318 guidelines). The beam experienced dead load due to self-weight only. Assume all loads are uniformly distributed. The ultimate moment is 109 kip-ft.

The beam experienced severe corrosion and has lost the concrete in regions along the bottom of the beam. An evaluation showed that only 60% of the flexural rebar area was sound and free of rust.

Assume that the concrete beam has been cleaned and patched.

Tensile strength: 380 ksi

Elastic modulus: 22,000 ksi

Width: 4, 6 or 8 inch

Thickness: 0.05 inch

Environmental reduction factor (exterior exposure)

Determine the AFRP bars required to make the beam safe. Show all seven steps. Also, determine the AFRP sheets required for a safer beam in an alternative design. Compare the two design.

Answer rating: 100% (QA)

The Building Code Requirements for Structural Concrete Code provides minimum requirements for the materials design and detailing of structural concrete buildings and where applicable nonbuilding struc... View the full answer