Although prestressed concrete (PC) bridges with corrugated steel webs have become a promising form of bridge, their long-term behavior is not well understood. A study of their long-term behavior is reported. A numerical model to account for the creep and shrinkage of concrete and tendon relaxation was formulated and verified by test. Because the assumption that plane sections remain plane, commonly adopted in Euler-Bernoulli and Timoshenko beam theories, is not valid, an extended sandwich beam theory was used considering the presence of diaphragms and external tendons. The long-term behavior of a typical bridge of this type was studied and compared with that of conventional PC bridges with flat steel and concrete webs. The effects of diaphragm and interaction between web shear deformation and local flange bending of the bridge were found to relieve with time. Moreover, the long-term deflection of this type of bridge was larger than that of the counterpart bridges.