Research on long-term deformation monitoring of PC box girder bridge strengthened by a cable-stayed system

To study the down-warping improvement for main girder of Dongming Huanghe River Highway Bridge after the reinforcement of the cable-stayed system, the long-term data of the main girder deflection were collected from 2018 to 2020, and the effects of different years, quarters and span on main girder deflection were analyzed, the results showed that the main girder deflection tended to be stable within 9 months after the reinforcement, the down-deflection trend of main girder was effectively suppressed within 3 years, and the effect of the cable-stayed reinforcement was obvious. Compared with 2018, the mid-span of main girder was generally raised in the first quarter of 2020, but the mid-span down-deflection was increased in the second, third and fourth quarters. In the relatively high average atmospheric temperature of each year, the main girder had improved as a whole, and the temperature had a great influence on the deflection of main girder, especially in the third quarter of higher temperature, it can be seen that the deflection of each span fluctuated greatly.