Abstract: Stresses in reinforced concrete beam under synergistic effects of cyclic freeze-thaw, deicing-salt attack, rebar corrosion and four-point bending were analyzed based on thermomechanics and mechanics of materials,and the distribution of these stresses with damage evolution in concrete were investigated. As a result, a series of formula for calculating thermal and mechanical stresses in the concrete were presented. It was found that the thermal stresses are distributed nonlinearly along the length of the beam sample and that the bending stresses depend on the ratio of steel modulus to the concrete modulus. The results indicate that the damage of the concrete under the synergistic loads is a combination of thermal fatigue and corrosion penetration.