An Adjustment Technique for Tensions in the Cables of Concrete Cable-Stayed Bridges considering the Effect of Cable-Girder Temperature Difference

Abstract

To make sure the tension adjustment in the cables of concrete cable-stayed bridges is conducted successfully, a new adjustment technique for the tension adjustment is presented, with the cable-girder temperature difference taken into account. The tensions are measured via frequency method. Prior to the tension adjustment, tensions and temperatures of all cables and girders are measured when the ambient temperature is stable, and this set of tensions is taken as reference tensions. During the tension adjustment, the relative variable quantities of the tensions are regarded as the control values, while the vertical displacement in the mid-span section of the main span is regarded as the verification value. After each pair of cables is adjusted, it is required to measure the temperatures of cables and girders as well as the vertical displacement variation in the mid-span section of the main span. To guarantee the structural behavior of entire bridge is controlled, at one-third cable points, two-third cable points and the farthest cable points, the frequencies of each pair of cables as well as the temperatures of each pair of cables and girders should be measured so as to recalculate the cable tensions. After that, these cable tensions are compared with the theoretical ones to ensure the structural behavior of entire bridge in control. Finally, Furong bridge, a concrete cable-stayed bridge with double inclined pylons, is taken as a sample application of this proposed technique. The results of cable tensions in this bridge illustrate the new adjustment technique is both accurate and efficient.