100 300 H 4.8 kPa surcharge floor load Pp = 600 kN PL = 800 kN C L MD = 20 kN-m M₁ = 30 kN-m 16-mm-diameter longitudinal bars and dowels 16-mm-dia. bars 75 clear cover An architectural requirement of 375 mm by 375 mm column is provided. The design loads supported by the column from structural analysis are as follows: Dead Loads: Axial Load Reaction P 600 kN Internal Moment Reaction M 20 kN-m Live Loads: Axial Load Reaction P Internal Moment Reaction M 800 kN 30 kN-m The NSCP C101-15 Table 405.3.1 applicable load combinations are: U U 1.4D 1.2D + 1.6L The reinforced concrete material strengths are as follows [NSCP C101-15 Sec. 419.2.1.1 and Table 420.2.2.4(a)]: Se Sy 28 MPa at 28 days 420 MPa and uncoated steel It is required to design the square tied column and the supporting square spread footing. Use 16-mm-diameter steel reinforcement following ASTM A615. The dowels may be required to carry some of the column load across the column-footing interface. The top of the footing will be covered with 300 mm backfill soil with a density of 16 kN/m³, and a 100-mm-thick basement floor. The basement floor load is 4.8 kPa and serves as a surcharge. For shallow foundations, the allowable bearing pressure is 290 kPa for medium stiff clay soil.

Question

A square spread footing supports a square tied column as shown. Assume that the reinforced concrete is normal weight (24 kN/m3) and = 1.00 (NSCP C101-15 Table 419.2.4.2). The column has a height of 3.5 meters. 1. Compute the development length ld (mm) of the column reinforcement embedded to the spread footing. It is permitted to set Ktr = 0. 2. Determine the required number N of dowel bars which carry some of the column load across the column-footing interface.