Serviceability

As has already been mentioned, correct behaviour in the service state will often be achieved by placing the reinforcement in the directions where tensile forces act in the elastic mode. The two strut-and-tie models below are in equilibrium and comply with the lower bound theorem.

• In the first model below, the reinforcement is arranged in the directions where tensile forces act in the elastic mode, and this model exhibits good behaviour in the service state.

Satisfactory behaviour under service state

• In the second model below, no bottom reinforcement has been provided, resulting in significant and uncontrolled cracking occurring in the lower area.

Unsatisfactory behaviour under service state