Fatigue resistance evaluation for couplers of existing post-tensioned, concrete bridges

Abstract

The risk of a fatigue failure has to be evaluated at coupling joints of older post-tensioned, concrete bridges in Germany, because weaknesses were identified in the design of these bridges. Because of the nonlinear bearing behaviour of post-tensioned, concrete structures, the results of this analysis strongly depend on the distribution of the permanent internal forces, which are uncertain due to time-dependent losses and redistributions. In this paper, a method to determine the bearing behaviour and the actual bending moment of the examined coupling joint, which is based on non-destructive, long-term measurements under service conditions, is shown. Therefore, the crack at the coupling joint, the temperatures and the traffic loading are observed. The results are used to calibrate a finite element simulation of the cross section. With this, a more realistic fatigue evaluation could be done as of the approaches in codes for the design of new bridges are used (e.g. DIN EN 1992, 2011, Eurocode 2. Bemessung und Konstruktion von Stahlbeton- und Spannbetontragwerken, Berlin: Beuth).