PSI - Issue 84

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ScienceDirect

Procedia Structural Integrity 84 (2026) 1183–1190

© 2026 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Conference Keywords: Prestressed concrete girders; Existing bridges; Residual prestress; Assessment; Non-destructive test; Stress release; Saw-cut test. 1. Introduction A large portion of the European road and railway infrastructure was built using prestressed reinforced concrete (PRC) girders, particularly between the 1950s and early 2000s. This structural solution was widely adopted due to its favourable uncracked behaviour under service conditions, reduced deflections and improved durability compared to conventional reinforced concrete. In recent decades, however, many existing PRC bridges have exhibited structural anomalies, such as extensive cracking patterns and excessive deformations, indicating that the effective prestressing level may be significantly Abstract The residual prestress evaluation in prestressed reinforced concrete (PRC) bridges is a crucial step in determining their actual stress field, residual shear capacity and overall structural reliability, especially in cracked or damaged structures. This paper presents the results of an experimental program carried out on deteriorated prestressed girder bridges subjected to accurate level 4 investigations, as defined by the Italian Guidelines (LLGG) for the safety assessment of existing bridges. To estimate residual prestress, pairs of saw cuts are performed on the girder webs applying the stress-release technique. The experimental results are compared with an analytical and numerical estimation, providing a comprehensive framework for validation. The study highlights both the methodological challenges associated with in-situ application, due to several influencing factors and uncertainties, and the potential of this approach, in specific cases, as a practical tool for residual prestress assessment. III Fabre Conference: Existing Bridges, Viaducts, and Tunnels: Research, Innovation, and Applications Residual prestress evaluation in prestressed concrete bridges using in situ stress release technique Giulia Rossini a, * , Stefano G.Mantelli a , Fausto Minelli a a Dipartimento di Ingegneria Civile, Architettura, Territorio, Ambiente e di Matematica, Via Branze 43, 25123 Brescia, Italy

* Corresponding author. E-mail address: giulia.rossini@unibs.it

2452-3216 © 2026 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Conference 10.1016/j.prostr.2026.06.151