Temperature Induced Deformations in Match-Cast Segments

Abstract

Summary Precast segmental hollow box girder bridges have become the preferred constructions method for many elevated highway projects in the last years. Although many segmental bridges had been built so far some significant design aspects need still further investigation. One is the bowing of match cast segments caused by the temperature gradient during hydration of concrete. The resulting gap between two adjacent elements may significantly reduce the durability and the load bearing capacity of the structure. A thermo-mechanical finite element model was developed to simulate the behavior of segments during match-casting. A numerical simulation of a real segmental bridge consisting of bowed and perfect fitting segments and dry joints will be presented in this paper. Keywords : segmental bridge; numerical modeling; thermal deformations; thermal stresses; bowing effect 1 Introduction In contrast to classical monolithic constructions a segmental bridge consists of small precast elements, called segments, which are stressed together by external tendons (see Figure 1, 2). Segmental bridges are often built as a single span structure in order to avoid coupling of the post tensioning cables and joints near the intermediate supports. Each span consists of three different segments namely pier, deviator and standard segments. Dry or epoxy joints are used between the segments. The shear keys at the element faces are designed to carry the shear loads at the joints, where also the friction between the joint surface takes apart in resisting shear forces.