In recent years, steel, trapezoidal box-girders for curved highway interchanges have been used extensively. For these structural systems, the majority of the steel girder cross-sectional stresses occur during the concrete pouring sequence. This paper describes a comprehensive study on the behavior of curved girders during construction. Data collected for the current research shows significant differences between the measured and predicted quantities, particularly for later pours. An overview of the steel-concrete interface behavior at early concrete ages and the development of an analytical tool to predict the response of systems with semi-cured concrete are given. Field monitoring of two bridges during construction is presented. The measured results were compared to analytical predictions obtained using software developed specifically under this research to address deficiencies with currently available analytical tools. Accounting for strength and stiffness gained throughout the construction process, the developed software is able to accurately capture girder stresses during construction, (C) 2004 Elsevier Ltd. All rights reserved.