PSI - Issue 84

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ScienceDirect

Procedia Structural Integrity 84 (2026) 569–574

III Fabre Conference: Existing Bridges, Viaducts, and Tunnels: Research, Innovation, and Applications Assessment of Gerber half-joints: comparison between experimental results and practical engineering approaches

Beatrice Baldan a , Carlo Pellegrino a , Riccardo Piazzon a , Paolo Zampieri a * a Department of Civil, Environmental and Architectural Engineering, University of Padova, Padova, 35122, Italy

© 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) Abstract In recent years, increasing attention has been directed toward the evaluation of critical structural components in existing bridges, particularly Gerber half-joints, which are widely used in bridge superstructures designed in the last century. These joints are characterized by their vulnerability due to difficulties in inspection, susceptibility to deterioration, and brittle, sudden failure modes. Furthermore, there is a scarcity of tools available for their structural assessment during service. This study presents a comparative analysis between experimental results reported in the literature and the estimates obtained through methodologies commonly adopted in engineering practice to assess the ultimate capacity of Gerber half-joints. Strut-and-tie models were developed in Matlab. The findings show good agreement with experiments in some cases, but also significant overestimations in others, highlighting the need to consider both compressive struts and tensile ties. This study adds insight to these approaches for the structural evaluation of Gerber half-joints in existing bridge infrastructure.

Peer-review under responsibility of the scientific committee of the Conference Keywords: RC half-joints, Bridge maintenance, Limit analysis, Structural assessment.

1. Introduction A large portion of the existing bridge stock, designed and constructed during the second half of the twentieth century, relies on Gerber systems with reinforced concrete half-joints to support suspended spans. Although this structural scheme provides static determinacy and tolerance to differential settlements and thermal effects, half-joints represent critical regions within bridge superstructures. Their structural behavior is strongly influenced by complex

* Corresponding author. E-mail address: paolo.zampieri@unipd.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.2026.06.073