Ultimate load behavior of post-tensioned prestressed concrete girder bridge through in-place failure test

Prestressed concrete girder bridges have been most widely employed in the construction of highways. It is frequently questioned that the true load-carrying capacity of the prestressed concrete girder bridges is underestimated and cannot be obtained realistically due to the limitation of load tests under service loads. The purpose of the present study is to explore the actual load capacity of the prestressed concrete girder bridges and to examine the structural behavior under service load as well as ultimate load stages. To this end, a special loading system has been designed to test the full-scale bridge system at the site. The concrete and steel strains, deflections, and crack widths have been automatically measured at each loading step up to ultimate load stage. The first cracking load of 313 kN is found to be approximately the same as the design live load of the bridge, and the bridge exhibits the satisfactory. service load behavior The concrete median strip made monolithically with the slab shows some contribution to the stiffness increase of the slab-girder system. The compressive crushing failure of the curb in the loaded side occurred just before the ultimate stage of the slab-girder system, which can be a warning indicator before the bridge system failure. The test results show that the ultimate load capacity of the tested bridge is approximately 10 times larger than the design service live load. Thus, the bridge system as a whole maintains much more safety margin than required. This fact must be correctly reflected for the realistic and economic design of the prestressed concrete girder bridges. The present study provides very useful and important field data that can be efficiently used for the accurate safety assessment and design improvement of prestressed concrete girder bridges.