FRACTURE CAUSE ANALYSIS OF TENSION ROCKER BEARING CABLES AT SUBSIDIARY PIERS IN A PRESTRESSED CONCRETE CABLE STAYED BRIDGE

In some prestressed concrete cable stayed bridges, the tension rocker bearing cables were provided at each subsidiary pier to resist a negative reaction force caused by service loadings. The tension rocker bearing cables were important members remaining the designed structural system of a bridge. Based on Yonghe Bridge of Tianjin in China, its construction stages and later maintenance processes are analyzed, and then a plane fi-nite-element model used for analyzing global effects of the bridge is established. The calculation results are com-pared with measured results, including the current geometry of bridge deck, cable forces and the inclined dis-placement at the top of towers. And then the model is checked and modified. Finally, an effective and corrective model is obtained. The model is used to calculate the axial force at tension rocker bearing cables. Thus, some fracture causes of tension rocker bearing cables are analyzed and identified. Results show that, the insufficient compression reservation between its main girder and subsidiary piers exists at its original finished dead stage. Moreover, the steel wire rust corrosion and fatigue are the essential fracture causes. Besides, the overloading ac-celerates the fracture process, but later maintenance or strengthening measures contribute little to fracture. Based upon these causes, some design advice for the rehabilitation of tension rocker bearing cables and later mainte-nance suggestions are presented.