PSI - Issue 78

Marco Gaetani d’Aragona et al. / Procedia Structural Integrity 78 (2026) 968–975

969

1. Introduction In recent years, the structural assessment of existing reinforced concrete (RC) bridges has received increasing attention due to several collapses, primarily attributed to inadequate maintenance (Domaneschi et al., 2020). In this context, one of the most recurrent phenomena compromising the load-bearing capacity of existing RC bridges is the onset and progression of corrosion in critical structural members (Crespi et al., 2022). Consequently, various studies have proposed different methodologies to evaluate the impact of corrosion on the load-carrying capacity of such structures (Zhao et al., 2021). Among the various components of a bridge, piers represent the primary load-bearing elements, and their deterioration can markedly reduce the seismic performance of the entire structure (Yuan et al., 2017). A key issue in evaluating the behavior of corroded RC piers is the potential non-uniform development of corrosion along the column height (Zhao et al., 2021). In road-type bridges, even when not directly exposed to aggressive marine environments, the lower portion of the pier is particularly vulnerable to corrosion due to the action of surface runoff from rainwater. existing RC members exhibiting flexure-shear critical behavior, such localized degradation may lead to a change in the failure mechanism (Xu et al., 2020) that can significantly affect the future seismic performance of exposed members. While many studies have addressed the behavior of multi-column bents only exhibiting ductile performance, this paper investigates the effect of a non-uniform corrosion distribution on the response for a multi-column bent with RC piers having flexure-shear critical behavior. The aim is to assess potential changes in the collapse mechanism using a refined finite element modeling approach that employs a mixed lumped-distributed modeling strategy to simulate the seismic behavior of existing multi-column bent (Gaetani d’Aragona et al., 2025) . 2. Modeling approach for Multi-column bents To accurately simulate the flexural response of RC columns while capturing potential brittle failure mechanisms, a mixed distributed-lumped modeling strategy, introduced in Gaetani d’Aragona et al. (2025) to model the overall behavior of typical overpass bridges, is adopted.

Shear spring

Evolutive model for shear-axial failure of RC columns

Elastic element

Rigid element

Pre-failure backbone

Shear limit curve

V

V

V

V

Bi-directionalbar-slip spring

K t

K deg

Axial Limit State spring

deg

K

unload

V res

 a

 s

Axial support spring

 tot=  shear +  flex

 res

 flex

(b)

(c)

(d)

P P s

Shear Limit State spring

Axial limit curve

Force-based column element

 tot

(e)

Bi-directional bar-slip spring

Rigid elements

Vertical

Transverse

(a)

Fig. 1. (a) Schematic layout for OpenSees model of bents and (b) evolutive model for shear-axial failure of RC columns.