Reinforced Concrete Design

One-way Slab

Effective Depth

Stress Calculations in Prestressed Sections

A prestressed concrete beam is 250 mm wide by 500 mm deep with a simple span of 6 m. The beams are pretensioned with a prestressing force of 650 kN at an eccentricity of 100 mm. Loads on the beam: Total Dead Load = 6 kN/m Live Load = 8 kN/m Compute the stress at the bottom fibers of the beam at midspan due to initial prestressing force alone.

NON-RECTANGULAR SRB

Compute the ultimate moment capacity of the beam shown. Assuming fy = 345MPa and f'c = 21MPa

T-BEAMS

If the beam is reinforced for tension only, determine the ultimate moment capacity when the depth of the compression block equals the flange thickness, or a = t. Given: bf = 1500 mm, t = 100 mm, bw = 250 mm, d = 470 mm, f'c = 30 MPa, fy = 345 MPa.

Footings

A column carries a net load of 550 kN to an isolated square footing sized 3 m x 3 m. The footing's thickness is 0.50 m, and the unit weight of concrete is 24 kN/m³. The allowable soil bearing capacity is 250 kN/m³. There is a small load eccentricity of e = 80 mm (0.080 m). Check whether the footing is adequate by computing the average soil pressure, including the weight of the footing.

Shear in Beams

Determine the spacing of vertical stirrups near the left support (d) of the beam loaded as shown in Figure. Given the following data: Bw = 305 mm d = 590 mm PD = 110 kN PL = 140 kN f y = 275 MPa f'c = 25 MPa WL = 34 kN/m Wd = 30 kN/m Compute the nominal shear carried by the concrete, nominal shear carried by the shear reinforcement, and required spacing of 10 mm vertical u-shape stirrups, respectively. NOTE: USE THREE(3) DECIMAL IN EVERY CALCULATIONS.

Tied and Spiral Columns

Pₙ = 3456 kN. A 400 mm x 400 mm tied column is constructed with f'c = 24 MPa and fy = 456 MPa, using 24 mm diameter bars. Determine the required number of bars, N.