Evaluation of creep and shrinkage in a prestressed bridge using data from laboratory experiments and in-situ monitoring

The recent construction of the Tauranga Harbor Link (THL) bridge, a 12 span post-tensioned structure built using the incremental launch technique, created a research opportunity to evaluate performance of such structures via in-situ monitoring. The girder was instrumented with a number of strain gauges and displacement sensors that track slow deformations due to shrinkage, creep and temperature effects with the purpose to increase the knowledge about the influence of these factors on performance of prestressed bridges. These studies are being accompanied by laboratory shrinkage and creep tests on concrete samples in order to evaluate the accuracy of predictions offered by several empirical material models. This paper describes the THL bridge, the monitoring system and laboratory shrinkage and creep tests. Based on these laboratory results recommendations about the suitable empirical creep and shrinkage prediction models are made. Preliminary, qualitative analyses of in-situ monitoring data are also provided.