Effect of pre-stressing on the axial shortening of continuous beam bridge

An analytical study is carried out to present the effect of the degree of prestress (D. P.) on the axial shortening of. continuous beam bridge. An emulational model is built first with the real condition of a partial prestressed concrete (PPC) continuous beam bridge with a D. P. of 0.95. The reliability of the model and analytical method is verified by the close agreement between the calculation. and test results. Then other four models with different D. P.s are built based on the original one through changing tensile controlling stress. Depending on the five models' calculating results, plots of the total axial shortening and the axial shortening due to five interrelated parameters versus D. P. are presented and analyzed. The analytical study shows that the axial shortening due to dead load, shrinkage and temperature change is invariable 'with various D. P.s. The axial shortening due to creep is found to increase when D. P. increases, while the axial shortening due to prestressing increases during construction and decreases in service. The total axial shortening is also found to increase with an increase of D. P.