Inelastic behaviour of externally prestressed continuous composite box-girder bridge with prefabricated slabs

摘要

For continuous composite bridges with prefabricated slabs, it is necessary to introduce prestress for ensuring serviceability of the deck in terms of cracking. Because of complex stress distribution in negative moment regions due to internal or external prestressing, flexural behaviour needs to be evaluated through experiments. Static tests on a continuous composite box-girder bridge of 20-20 m span with prefabricated slabs prestressed by two prestressing methods, internal prestressing before shear connection and external prestressing after shear connection, were conducted. Static behaviour of the model was investigated to estimate flexural performance after cracking and to evaluate ultimate strength. Simple plastic analysis was carried out to estimate the ultimate flexural capacity of the continuous bridge. The tension stiffening effect of the concrete deck in a negative moment region and the incremental prestress of external tendons were evaluated.