Comparing eurocode 2 prestress loss estimations to strains measured on a pretensioned bridge beam

Abstract

The implementation of Eurocode 2 (EC2) for the design of concrete structures in South Africa in the near future is pending and necessitates refined understanding of EC2’s prediction models; including prestress losses and the validity of these estimates for local materials and environmental conditions. In this study, the EC2 prediction model for prestress losses was investigated from the perspective of using assumed or calculated values as well as measured data as inputs. The calculated values were compared to the deformations measured on a pretensioned bridge beam with a 33 m span that was instrumented with Vibrating Wire Strain Gauges. The measured deformation was used to not only estimate the instantaneous elastic deformation but also derive functions for estimating shrinkage and creep with time. These functions were compared to the design estimates obtained from EC2. The study focused on the prestress losses attributed to the concrete as well as the manner in which the input parameters of the EC2 model relate to these losses and provides insight and understanding into the application of empirical expressions EC2.