The behaviors both in case of local span and whole span in fire were investigated by the finite element method.The result showed that: when the location of the fire was different

the location and scope of the plastic hinge were different

but in both cases the scope of plastic hinge appeared in the middle abutment;the destroy hinge appeared in the end of the negative moment reinforcement

so the length of the negative moment reinforcement had a significant effect on structural fire resistance;when the whole slab was fired

the middle span rose because of the whole structure′s plastic result and at last presented promontory

but when the slab was fired in local middle span the deflection of the middle span was descent always;when the structure was fired in local span there was a great degree of internal force adjustment

which could improve the fire resistance of structure

so the fire resistance of structure fired in local span was much better than the fire resistance of structure fired globally.