PSI - Issue 78

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 78 (2026) 199–206

© 2025 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 XX ANIDIS Conference organizers Keywords: Bracing; Concrete; Connection; Model; Steel. Abstract A steel bracing system located externally to an existing reinforced concrete (RC) frame structure has been recently known as “exoskeleton”. Generally, the exoskeleton needs to be efficiently connected to the existing RC frame. In Europe, the design of steel connections is regulated by EN 1993-1-8, while steel-to-concrete connections shall also satisfy the requirements of EN 1992-4. EN 1993-1-8 adopts the “component method”, schematizing a connection as an assembly of rigid bars and (elastic plastic) springs and allowing to calculate the moment-rotation-axial force response in both elastic and plastic ranges. EN 1992-4 mainly addresses the calculation of the resistance of tension anchors involving concrete failure, although suggesting rules to calculate tension forces on anchors based on a very traditional elastic analysis replicating methods of RC column section analysis. Using the component method of EN 1993-1-8, but considering the provisions of EN 1992-4 for concrete failure, seems a reasonable procedure to follow, as also suggested by EN 1993-1-8. However, the only type of hybrid steel-to-concrete connection explicitly considered in EN 1993-1-8 is that with an unstiffened plate at column bases. Instead, using a stiffened connecting plate could be of great aid for connections between a seismic steel exoskeleton and the RC frame, because of the large values of the internal forces to be transferred. Therefore, the objective of this paper is to propose and discuss a component model for hybrid steel-to-concrete connections with stiffened plates. The proposed approach is an extension of the method stipulated by EN 1993-1-8 for column base plate connections, with differences in the evaluation of the position of the neutral axis and the effect of prying forces. The application of the model to a few case studies is subsequently described, and the model predictions are compared to numerical results obtained by means of finite element models developed with Ansys. XX ANIDIS Conference Connections between steel exoskeletons and RC frame buildings: stiffened plates Gaetano Della Corte a * a University of Naples Federico II, Via Claudio 21, Naples 80125, Italy

* Gaetano Della Corte. Tel.: +39 081 7683131. E-mail address: gaetano.dellacorte@unina.it

2452-3216 © 2025 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 XX ANIDIS Conference organizers 10.1016/j.prostr.2025.12.026