Seismic vulnerability assessment of reinforced concrete bridge piers with corroded bars

Abstract

Reinforced concrete (RC) structures located in aggressive environment, for example, RC bridge piers close to the sea and experiencing chloride attacks, may be exposed to an increased seismic vulnerability. This requires practical yet effective safety assessment strategies aimed to determine the seismic behavior by incorporating corrosion deterioration phenomena. An easy‐to‐use phenomenological model is here developed to describe the seismic behavior of corroded RC elements based on a fiber hinge formulation wherein the corrosion‐induced mechanical degradation of concrete and steel is implemented through appropriate constitutive laws at the fiber level. The developed fiber hinge formulation is first validated against experimental cyclic tests of corroded RC columns from the literature. Then, the proposed approach is used for the seismic vulnerability assessment of the Zappulla multi‐span viaduct (southern Italy), whose RC bridge piers (with a box‐shaped, two‐cell hollow rectangular cross section) are exposed to carbonation and chloride‐induced corrosion. A comprehensive in‐situ testing campaign is conducted for the mechanical characterization of the materials in the RC piers. Corrosion potential mapping, carbonation tests and tensile tests on corroded bars extracted from RC piers are critically interpreted to calibrate the constitutive laws of the fiber‐hinge model. Motivated by experimental findings, numerical seismic analyses (including linear dynamic, nonlinear static and nonlinear dynamic analyses) are performed under two different corrosion scenarios to quantify the impact of corrosion on the resulting seismic vulnerability conditions of bridge piers with corroded bars. The proposed approach is characterized by low computational cost and lends itself to large‐scale seismic vulnerability assessment of other existing RC bridges placed in corrosive environment.

Evaluation of the pull‐out test to determine the residual prestressing in concrete bridges.

“…The issue related to this phenomenon is about to understand whether the structural behaviour of the bridge is affected under ultimate load conditions only, or also under serviceability loads. This is a relevant research topic which is currently studied with the aim to provide a rapid health monitoring of posttensioned bridges in both serviceability and ultimate conditions by performing experimental and numerical investigations, without invasive tests on material and structural members [15,16].…”

Capacity assessment of uncorroded and corroded dapped‐end beams by NLFE and strut‐and‐tie based methods

“…More recently, some NLFE results of degraded dapped‐end beams have been presented 35–41 . In particular, Santarsiero et al 35 proposed a 3D NLFE model for a dapped‐end with variable thickness where nonlinear truss elements were embedded in concrete.…”

“…Abeysinghe and Yapa 38 proposed a 2D NLFE model in which the effect of corrosion was modeled by reducing the cross‐sectional area of corroded rebars. In References 39–41, 2D and 3D NLFE models and S&T models are used to assess the load‐bearing capacity of Gerber saddles in existing bridges, again considering the effects of corrosion by reducing only the cross‐section of the corroded rebar, the concrete strength, and the prestressing force, while the reduction of the bond strength was modeled by reducing the yield strength of rebars.…”

“…In the above‐mentioned works, the NLFE models were validated with respect to experimental test on uncorroded specimens and then they were used to investigate the effects of corrosion on the structural response through sensitivity analyses at varying levels of corrosion, 35–41 without experimental validation. In general, for all models of corroded dapped‐end beams, the problem of their validation is an open issue, both because of the uncertainties of the corrosion parameters to be used as inputs 42 and because of a lack of experimental tests on corroded dapped‐end beams.…”

Reinforcement Corrosion in RC Hollow Piers: Destructive and Non-Destructive Tests

“…Corrosion of the reinforcement was found to be the predominant deterioration mechanism for RC structures, impacting infrastructure resilience [ 10 ], and this has potentially critical consequences for safety and serviceability [ 11 , 12 , 13 ], with impacts on sectional strength [ 14 , 15 , 16 ] and ductility [ 17 , 18 ] capacities. The degradation of the materials (steel and/or concrete) decreases the overall seismic performance of bridges [ 19 , 20 ] and different corrosion levels, due to exposition time and environment [ 21 ], or uniformity of corrosion [ 22 ], or retrofitting with composite jackets [ 23 ] have a clear impact on failure mode and seismic capacity in general.…”