Temperature Induced Deformations in Match-Cast Segments and their Effects on Precast Segmental Bridges

Autor(en): Abendeh, Ra’ed Hamburg-Harburg, 09. November 2006 Seiten: 202 Auflage: 1 Sprache: EN ISBN-10: 3867270511 ISBN-13: 9783867270519 Zugeordnete Fachbereiche: Maschinenbau-und Verfahrenstechnik Kategorie: Dissertation Bezugsmöglichkeiten Print Version 28,00 € 26,60 € In den Warenkorb eBook (5067.4 kB) 28,00 € In den Warenkorb

Kurzbeschreibung

Segmental construction in the field of prestressed hollow box girders concrete bridges can be considered one of the most interesting and important achievements in bridge engineering in the last decades. In urban areas the very fast erection without interrupting the traffic underneath is an important advantage for these types of bridges.
Match-cast method especially the short line match casting is most of the time used as a segment production technique for post-tensioned hollow box girder segmental bridges to guarantee a perfect fitting of adjacent segments. When a new segment is to be cast against an old one, a problem can appear due to temperature development by the heat of hydration which can lead to the bowing effect. The resulting segments have one straight and one curved side. The bowing effect may significantly reduce the durability and the load bearing capacity of the structure. Few experimental data has been published about this phenomenon and a systematic study is still missing.
A thermo-mechanical finite element model has been developed to simulate the behaviour of segments during match-casting. The temperature distribution within a body and the subsequent thermal stresses and deformations under any stable or variable boundary condition with respect to time can be analyzed. Test results from the San Antonio (Y project) and the Bang Na (BBBE) segmental bridges were used to verify the complex numerical model. A good agreement has been obtained. The influence of different environmental conditions, the shape of the segment, and use of insulating materials on the bowing effect have been studied.
At the erection site, the bow shaped segments have particular problems during the epoxy and temporary post-tensioning operations. One may have problems in closing the joints and the bowing deformation reduces the required compressive stresses for the epoxy resin. Moreover, this phenomenon not only poses problems in construction but also it could lead to areas of reduced compression in the segment’s centreline, meanwhile stress peaks occur at the tips of the segment’s cantilever slab. A numerical simulation of two typical real segmental bridges, namely the Second Stage Expressway System (SES) and Bang Na segmental bridges, consisting of perfectly fitted or bow shape segments with dry joint has been developed. The results show that compressive stresses and the load bearing capacity of the structure as well as the durability and deflections are highly influenced by the bowing effect.

Keywords : Segmental Bridge; Match-Cast Method; Bowing Effect