Question

An ___________________ beam is one in which the tension capacity of the tensile reinforcement is smaller than the combined compression capacity of the concrete and the compression steel (under-reinforced at tensile face).

(a) extra-reinforced

(b) less-reinforced

(c) under-reinforced

(d) over-reinforced

I had been asked this question during an interview.

The question is from Earthwork, Concrete and R.C.C. work in portion Rules and Methods of Measurement of Civil Engineering Drawing

Answer 1

Right answer is (c) under-reinforced

To explain: When the reinforced concrete element is subject to increasing bending moment, the tension steel yields while the concrete does not reach its ultimate failure condition. As the tension steel yields and stretches, an “under-reinforced” concrete also yields in a ductile manner, exhibiting a large deformation and warning before its ultimate failure. In this case the yield stress of the steel governs the design.