Experimental Study Of Prestressed Box Girder Construction Combination Of Defects And Mechanical Analysis

The pre-stressed concrete box beam bridge is one of the most popular beam bridge structures. With the deeply developing of the traffic and the transportation, massive prestressed concrete box beam bridges have been builded in recent years. At the same time, it is occurred of various quality problems on the pre-stressed concrete box beam bridges. According to the results from statistics and the analysis, one of the main reasons of the quality problems is from the constructional deficiency.Theoretical analysis, experimental validation and engineering practice are the three pillars of the establishment and development of structural engineering. A one-half scale modle of the 30m prestressed concrete box beam was built, and the deficiencies on the pouring and vibrating of concrete and the tensioning of pre-stressed wires were specified. Then a test beam with given assembled deficiencies was made. Through the dead load destructive test on the deficiencying beam, the loading proess and the destructional form of the beam was detected, and the influence of the constructional deficiency on the beam was analysised. Further more, a 3D finite element analysis on the deficiencying beam was done to compare with the test results of the deficiencying beam.According to the contrast analysis result of the dead load destructive test and the finite element analysis, the following conclusions was obtained:1) The given deficiencies are not much influnce to the bearing capacity of the deficiencying beam. According to Code for Design of Highway Refinforced Concrete and Prestress Contrete Bridges and Culverts, The ratio of the actual limit bearing capacity to the theory value is 1.77, and there is more safety capecity with the deficiencying beam.2) The given deficiencies can much influnce to the durability of the deficiencying beam. Because of the less of a tensioning of pre-stressed wire at one side of the beam, the cracks apeared and developed early on the same side. It could expected that the durability of the deficiencying beam will decrease in the long-term using process.3) The less of a tensioning of pre-stressed wire at one side of the beam will not cause much tersion to the deficiencying beam. According to the finite element analysis and the testing results, the strain-stress curve of the experiments beam is in line elasticity stage before the crack appeared, and the tersion was not obviously.