Research on strengthening suspended deck system for half-through CFST arch bridge by setting longitudinal steel-tubular trusses

摘要

The crossbeams are the main members for suspended deck system of many existing half-through CFST arch bridges. And the suspended longitudinal RC T-shaped floor beams in the through part of the bridge are supported on the PC cross beams which is suspended by high tensile steel cable hangers to the arch ribs. Such a deck system without a longitudinal stiffening girder will cause large deflection and vibration because of its weak integrity as well as vertical stiffness. Therefore, it is necessary to carry out research on strengthening of such kind of deck system to improve the risk-resistance capacity. Taking Shitanxi Bridge as an example, the strengthening project is proposed by setting longitudinal steel tubular trusses between the crossbeams. The static and dynamic behaviors of this bridge before and after strengthening were analyzed and field tests for both static and dynamic behaviors after strengthening were also carried out. Analysis and test results show that setting steel tubular truss beams between the crossbeams is effective on improving the dynamic performance and risk-resistance capacity for the suspended deck system of half-through or through CFST arch bridges without longitudinal stiffening beams. This strengthening method is not only economic and applicable, but also has little influence on traffic flow during construction.