We applied compression test on concrete because compression strength is a key goal to achieve for concrete strength.
On another hand, we applied tension test on reinforcement because tension strength is a key goal to achieve on reinforcement.
So basically concrete use for achieving compression strength and reinforcement use for resist tension force.
Now come to the point
Concrete is strong in compression, is weak in tension so if we do not provide reinforcement in concrete then concrete in beam resist and transfer load effectively because stronger in compression.
But in beam compression and tension both act if we do not use reinforcement in the tension zone of concrete then it fails suddenly.
Here note point
If we do not provide reinforcement in concrete element then it's transfer compression force effectivly but not stand with tension force and fail suddenly people do not have time to safe their self due to sudden fail in tension.
- For elimination of sudden failure of the concrete beam or column, we provide reinforcement in concrete element.
- Before the failure of the structure, we have seen the sign of failure or sickness of structure like crack.
- By providing we increase the time of failure in tension.
- To make structure balanced in compression and tension zone for the durability of the structure.
- Increase the time of failure in tension.
- Make structure economical.