Abstract: The determination of static test load of single beam usually takes the loading efficiency of control bending moment as the control objective, and the conventional method is “moment equivalent method”. However, the actual stress characteristics of single beam do not conform to the stress state of the completed bridge, which makes the calculation value of test load distorted. In order to solve the above problem, this paper proposes a more practical “stress equivalence method”. By using MIDAS/Civil finite element software, the stress state of precast box girder with different spans is calculated, and the calculation results of “stress equivalent method” and “moment equivalent method” are compared and analyzed. The results shows that the “stress equivalent method”, that is, the superimposed stress or the bending moment calculated by the inverse superposition stress as the control index in the static load test, is closer to the actual stress state of the structure. Compared with the bending moment calculated by the “moment equivalent method” as the calculation method of controlling internal force, the “stress equivalent method” is about 12% less, which can reduce the misjudgment of load test, and has certain guiding significance for the load test of single beam of similar bridges.

Key words: moment equivalent method, stress equivalent method, control moment, loading efficiency, static load test