Which section is more ductile under reinforced and reinforced balance?

Over reinforced beam contains more steel and steel is more ductile than concrete. But the behaviour of an under reinforced beam is more ductile than of over reinforced beam because in under reinforced beam, steel failure occurs first due to maximum permissible stress of steel reaches first.

Why generally over reinforced section is avoided?

Why over-reinforced sections shall be avoided while designing the sections using limit state method? A section having percentage of tension steel greater than the critical percentage is known as over-reinforced section. Hence, this type of failure is usually avoided in ultimate strength design.

What is balanced section?

Balanced section is the section in which the stress acting in concrete and that applied in steel section will attain permissible value simultaneously. This means that the tension produced in the steel reaches their yield strain value at the same time, when the concrete attains the failure strain value in bending.

What are the over reinforced section and under reinforced section?

In an over reinforced section the percentage of steel provided is greater than the balanced section. So the actual neutral axis shift downward i.e., n>nc [Fig. 2.6(d)]. In this section, stress in concrete reaches its permissible value while steel is not fully stressed.

What are under reinforced and over reinforced beams?

Reinforced concrete beam sections in which the steel reaches yield strain at loads lower than the load at which the concrete reaches failure strain are called under-reinforced sections. Every singly reinforced beam should be designed as under-reinforced sections because this section gives enough warning before failure.

What is over reinforced failure?

Over-reinforced sections fail suddenly by compression concrete crushing when their ultimate compressive strain has been exceeded but the longitudinal reinforcement strain has not yielded.