625 mm 4 bars @ 28 mm + - 300 mm -
A reinforced concrete beam (see figure)
is acted on by a positive bending moment of
M = 160 kN . m. Steel reinforcement consists of
4 bars of 28 mm diameter. The modulus of elasticity
for the concrete is Ec = 25 GPa while that of the steel
is Es = 200 GPa.
(a) Find the maximum stresses in steel and concrete.
(b) If allowable stresses for concrete and steel are
σac = 9.2 MPa and σas = 135 MPa, respectively,
what is the maximum permissible positive
bending moment?
(c) What is the required area of steel reinforcement,
As, if a balanced condition must be achieved?
What is the allowable positive bending moment?
(Recall that in a balanced design, both steel and
concrete reach allowable stress values simultaneously
under the design moment.)
Step by step
Solved in 6 steps with 28 images
