Durability enhancement of half-joints in RC bridges through external prestressed tendons: The Musmeci Bridge’s case study > 기술자료실

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Durability enhancement of half-joints in RC bridges through

external prestressed tendons: The Musmeci Bridge’s case study

Giuseppe Santarsiero *, Valentina Picciano

School of Engineering, University of Basilicata, Viale dell’ateneo lucano 10, 85100 Potenza, Italy

A R T I C L E I N F O

Keywords:

RC bridge

Half-joints

Finite element

External post-tension

Durability analysis

Chloride corrosion

A B S T R A C T

This paper numerically investigates the effect of post-tension interventions to strengthen the

deteriorated half-joints of the Musmeci Bridge in Potenza (Italy), with the primary objective of

increasing the ultimate load-bearing capacity and monitoring the secondary effects in terms of

preventing or limiting cracking patterns. Bearing this in mind, the study aims to investigate the

role of the reinforcement detailing, of the post-tension stress and of the corroding time in the

presence of chlorides, outlining the intervention ability to improve the structure’s durability. To

this end, nonlinear finite element models are provided with chloride ions diffusion analysis to

investigate corrosion initiation and progress in reinforced concrete elements and account for

deterioration due to two scenarios (45 and 95 years). Results show the significant impact of

reinforcement layout as the presence of inclined bars increases the ultimate load by about 86 %.

The ultimate load improvement is in the range 50–55 % when the intervention is carried out after

45 years while it is equal to about 30–35 % if a period of 95 years is last since the construction.

This latter highlights the significant influence of the intervention timeliness on structural

durability.

1. Introduction

Old bridges have suffered a significant increase in traffic loads as well as in their frequency which determines heavier loading

conditions compared to design assumptions. Moreover, environmental stresses (e.g., carbonation chloride ingress, freeze-thaw cycles,

etc.) caused material deterioration which was accelerated by the lack of ordinary maintenance interventions. The joint effect of

material degradation and increased loading conditions is represented by a reduction of durability (i.e., the ability to accomplish their

intended purposes for a sufficiently long period, or at least during the expected service life). Huge efforts are needed from the financial

point of view to intervene on many bridges constructed after the Second World War using innovative prestressing techniques even

though with shallow material properties’ control [1]. Therefore, to optimise the use of financial resources for maintaining bridges,

effective technical solutions need to be experimentally tested and numerically verified.

Specifically, cantilever bridges were widely used in the past due to their intrinsic advantages linked to the stress distribution

coupled with their statically determinate condition. Key components of these bridges are half-joints, where cantilever and suspended

spans are connected [2]. These latter are frequently subjected to maintenance issues caused by the water seepage permitted by the deck

drainage malfunction leading the platform water to flow through the expansion joints [3], which are frequently in service after losing

their waterproof feature. Moreover, in harsh climates, platform water contains de-icing salts responsible for chloride ingress and