Behavior during construction of ramp B over I-40 in Nashville, TN
Dykas, Julia Catherine
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The construction of curved I-girder bridges generally requires detailed attention to the steel erection plan as well as the deck placement sequence. There is limited quantitative information available on the performance of large curved bridges under construction. This study seeks to address this limitation through the study of a curved ramp I-girder bridge. The bridge under study is the last of several bridges needed to complete the interchange between I-40 and Briley Parkway (TN SR155) in western Nashville, TN. The study consists of three parts. First, the bridge was instrumented and its behavior during construction was monitored using vibrating wire strain gages, clinometers, and a robotic total station. Through these technologies it was possible to monitor changes in strain/stress, angle of rotation, and deflections throughout the girder erection, installation of concrete formwork, and concrete placement. Second, a static load test of the completed bridge was conducted using ten trucks loaded to a total weight of 72 kips each, during which measurements of the stress/strain and deflections were acquired. Finally, the collected data was compared to analytical results obtained from a 3D finite element analysis (FEA) model to assess the correlation between measurements and refined analytical predictions. The refined 3D FEA predictions are used as a baseline for evaluation of various simplified analysis methods in a parallel National Cooperative Highway Research Program project, NCHRP 12-79, Guidelines for Analytical Methods and Construction Engineering of Curved and Skewed Steel Girder Bridges. Overall, the comparisons show that the 3D FEA model provides a reasonable approximation of the bridge's behavior in terms of both stresses and deflections.