Study On The Application Of Concrete Shrinkage And Creep Models On The Box Girder Bridge

The mechanical properties of concrete box girder bridge were significantly influenced by the coupling effect between concrete creep, shrinkage and temperature, as well as the randomness of them. The Koror-Babeldaob(KB) Bridge in Palau was cited as an example, a layered model considering the coupling effect and the randomness was established using Model B3 with Midas/Civil. The model were used to study the long-term mechanical behaviors of box girder bridge by deterministic and stochastic analysis. The main contents are following:(1)Summed up the relative research conditions on the coupling effect between concrete creep, shrinkage and temperature, as well as the randomness of them, then the factors that cause too big long-term deflection of concrete box girder bridge and the creep and shrinkage calculation theories and methods were introduced. It is focused on stating the approaches how to conside the coupling effect between temperature and concrete creep, shrinkage, the randomness of them.(2)Bsede on KB bridge’s measured deflection at mid-span after the bridge closure 18 years, a accurate numerical calculation model which takes account to the coupling between concrete creep, shrinkage and temperature was built to analyzed the long-term behaviors of the bridge. The results show that mid-span deflection of main span, the prestressing loss and stress on top slab of girderin negative moment region on top of the main pier are influenced significantly by the coupling effects, and the degree of influence changs obviously with the time. However, the stress on bottom slab essentially is unaffected by the coupling effects.(3)Based on the random variables of the material and environmental conditions parameters got by using Latin hypercube sampling, using the Model B3 and it’s parameters Set2-2010 the probabilistic creep and shrinkage models were established by soft Midas/Civil. The effect of the randomness of concrete creep and shrinkage on long term mechanical behaviors of the box girder bridge were discussed. It is found that mid-span deflection of main span and the stress on top slab of girder in negative moment region on top of the main pier are influenced greatly by the randomness, and the effect of temperature non-determinism on the discrete of mechanical behaviors can not be ignored.