Exploring behaviour factors and chord rotation in RC MRF structures: Nonlinear analysis based on second generation of Eurocode 8

• Type: Article in International Scientific Journal
• Date: 2025

Authors

Maranhao, H (Author) Other; Humberto Varum (Author) FEUP; José Melo (Author) FEUP

Journal

Title: Engineering Structures

Vol. 323

ISSN: 0141-0296

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 0 Citations

Other information

Authenticus ID: P-017-ACB

DOI: 10.1016/j.engstruct.2024.119252

Abstract (EN): Eurocode 8 is undergoing revisions, including introducing new ductility classes and displacement-based design methods alongside traditional force-based ones. Additionally, new detailing provisions for local ductility are being considered. A notable change in the second generation of Eurocode 8 is that it no longer requires direct verification of concrete core confinement at the base of columns when detailing for local ductility. This study examines these changes concerning moment-resisting frames that are regular in plan and elevation and nontorsionally flexible. The behaviour factor (q) components qR, qD and qS, and chord rotation (displacementbased) are analysed using nonlinear analysis and compared with the current and second-generation of the Eurocode 8. A mathematical model based on nonlinear analysis models has been developed to understand the implications of forfeiting the direct verification of concrete core confinement at the base of columns. Nonlinear analysis reveals higher behaviour factor values than those prescribed by the code, highlighting the safety characteristics of the second generation of Eurocode 8 and the implications of three-dimensional modelling. Results show that chord rotation models preconised in the second generation of Eurocode 8 demonstrate good approximation to the ones obtained by nonlinear analysis, with minor differences observed for the structures under analysis. The strong correlation observed in the developed mathematical model for concrete core confinement indicates that displacement-based design alone sufficiently ensures the safety of core confinement at the base of columns. This research innovatively validates the new ductility classes of Eurocode 8. It introduces a mathematical model that eliminates the need to verify concrete core confinement at column bases. Nonlinear analysis confirms that displacement-based design ensures safety, streamlines the design process and enhances understanding of structural behaviour under seismic loads.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 23