When a concrete slab of a bridge is constructed, the concrete
material is poured into each form consecutively. But due to a
unique nature of the concrete material, the slab will experience
a complex loading history. Namely, a concrete material will
generate heat under a chemical reaction, when elastic modulus
changes its value immediately after the pouring.
It accompanies a volumetric shrinkage due to dry out, when
the shrinkage strain is constrained by an adjacent already-
solidified concrete slab and steel girder. This constrained
shrinkage strain would trigger the crack propagation.