Integral abutment bridge design with thin-walled prestressed precast bridge girders

Abstract

Bridge construction has always been part of structural engineering, and has been evolving throughout the years. New construction technologies have been discovered to better use materials and construction techniques. Precast concrete is one of these evolving techniques that are being utilized more and more nowadays. The motivation behind this project is the use of prestressed precast concrete as a realistic replacement to composite construction of bridges. An existing composite overpass bridge, between the Austrian states of Upper Austria and Salzburg, is taken as a starting point to find out if it is possible to build a bridge with an equivalent bending stiffness with use of thin-walled prestressed precast bridge girders. These bridge girders allow the slenderness of the bridge to stay almost unchanged while decreasing the heavy weights having to be moved around during the construction of the bridge. The structural analysis of the bridge was carried out by first analyzing a 2-dimensional model to better approximate the prestress needed on each construction phase. Additionally a 3-D analysis was performed on a more accurate model to give the final internal forces with help of the software RFEM from Dlubal and with an excel spreadsheet programed to find the internal stresses on the girders of the structure. This research illustrates the plausibility of using prestressed precast concrete as a technique in order to build an overpass bridge with a span of ca. 47 m. The design was achieved by modeling the construction of the bridge in 5 construction phases. These phases help illustrate the internal forces at different points on the girders and the bridge's slab due to self weight as well as the prestressing loads being applied on the built in tendons. The research performed for this project is an addition to ongoing research on prestressed precast bridge construction at the Vienna University of Technology, but it already shows great potential to use prestress precast concrete