A rectangular reinforced concrete beam has a width of 300 mm
and an effective depth of 450 mm to centroid of the tension bars. The
beam is reinforced with six 32mmØ tension bars placed in two layers
with the outer layer having a depth of 478 mm, and two 28mm
compression bars with centroid 65 mm from the extreme concrete
fiber. Use the 2015 NSCP, f' = 34.5 MPa and fy = 345 MPa. Assume
that the concrete displaced by the compression steel shall not be
neglected and that the compression steel yields. Det. the following:
1. The balanced steel ratio if the beam is singly reinforced.
2. The maximum steel ratio for a singly-reinforced section in
tension control.
3. The maximum steel ratio for a doubly-reinforced section in
tension control.