Analytical Approach for Serviceability Assessment of Prestressed Concrete Girders Consisting of a Precast Beam and a Cast-in-place Slab

Abstract

This paper is focused on the assessment of the Serviceability Limit State of bridge girder cross-sections consisting of a precast, prestressed concrete beam and a cast-in-place top slab, which will be referred to as composite concrete sections because of the presence of more than one concrete within the section. Various methodologies for non-composite (i.e., with only one concrete within the section) concrete sections have been proposed by different authors to address the issue of stress assessment and crack control, mostly making use of analytical neutralization methods. In the present study, the neutralization method is extended and adapted to composite sections involving two concretes cast at different times. The proposed method is validated by comparison with a direct calculation method and commercial software. Three scenarios have been analyzed in the paper: midspan sections subjected to positive bending with cracking of the precast beam, sections at support regions of bridge girders subjected to negative bending in which the top slab is uncracked under permanent loads but undergoes cracking with the application of live loads, and sections at support regions in which the top slab is already cracked under permanent loads. Additionally, worked examples from real projects are provided.