Seismic Vulnerability of Bridges in Morocco Using Fragility Curves and Incremental Dynamic Analysis IDA: A Case Study of an Independent-Span Viaduct with Precast Reinforced Concrete Beams on the Selouane to Nador WESTMED Railway Link

¹ ABDELMALEK ESSAADI UNIVERSITY, National School of Applied Sciences AL HOCEIMA, Laboratory of Engineering Sciences and Applications, AL HOCEIMA, Morocco.
² National School of Applied Sciences EL JADIDA, CHOUAIB DOUKKALI UNIVERSITY EL JADIDA, Morocco.
³ Energy4Water Research Center (E4W) , University Mohammed VI Polytechnic (UM6P), Benguerir, Morocco.
⁴ MOHAMMED FIRST UNIVERSITY, OUJDA faculty of sciences, Laboratory of Engineering Sciences and Applications, OUJDA, Morocco.

^* Correspondance: This email address is being protected from spambots. You need JavaScript enabled to view it. , This email address is being protected from spambots. You need JavaScript enabled to view it. .

Abstract

Bridges represent critical yet vulnerable elements of Morocco's transportation infra-structure. This vulnerability is particularly concerning in seismically active regions such as the Nador area in northeast Morocco, where the convergence of the Eurasian and Nubian plates along the Alboran Sea generates significant seismic hazard. This study assesses the seismic vulnerability of a strategic viaduct on the Selouane-Nador WESTMED railway link, a vital connection to the Nador port, by developing analytical fragility curves. The methodology employs a probabilistic framework based on Incre-mental Dynamic Analysis (IDA), where a detailed finite element bridge model is sub-jected to 18 carefully selected seismic records.The results quantify the bridge's seismic performance, establishing median peak ground acceleration (PGA) thresholds of 0.25g, 0.55g, and 0.85g for the Immediate Occupancy (IO), Life Safety (LS), and Collapse Pre-vention (CP) damage states, respectively. Furthermore, the study translates these probabilistic results into practical decision-making tools by correlating the engineering damage states with the official bridge condition classification system used by the Mo-roccan Ministry of Equipment and Water. This integration provides infrastructure managers with a risk-based methodology to prioritize inspections, maintenance, and strengthening strategies, thereby enhancing the seismic resilience of essential bridge networks in Morocco.