Analysis of long-span prestressed concrete bridge based on the method of “zero bending moment of dead load”

At present main problems of long-span prestressed concrete girder bridges designed by traditional theory are excessive midspan sag. While the zero bending moment method can effectively reduce the structural deformation, using the prestressed bending moment to balance the moment produced by weight. At the basis of analysis on the traditional design theory and the zero bending moment method, the formula for calculating the effective prestress of each segment was derived according to the principle of "zero bending moment of dead load". Above two methods were used on the four bridges for comparison analysis, and the results showed that with the zero bending moment method, the stress difference of each section and deflection were smaller, ant that the structure had a strong safety reserve. It verified that the design theory of "zero bending moment of dead load" played a positive role on improving the deflection.