Retrofitting Alternatives for an Existing Maillart-Arch-Type Bridge: A Case Study

Abstract

This article examines different retrofit approaches for a still-in-use deck-stiffened arch bridge, the Viadotto Olivieri in Salerno (A3 Highway—South Italy). In its current state, the viaduct is characterized by a central Maillart-arch system, separated by 6 cm-deep joints from two lateral girder portions: the whole system works as an isostatic scheme on a global scale. Dating back to the 1960s, it derives from an early design approach, not including the effects of seismic actions. Considering the demands of current codes, also in light of recent bridge collapses and the resulting plan for assessing the structural safety and vulnerability of existing bridges, studies on seismic capacity become necessary to highlight the potentials and deficits of such complex structures. Analysing a still-in-use example of a Maillart-arch-type bridge, the article examines two different retrofit approaches. The first retrofit alternative includes the strengthening and partial modification of the original deck bridge: it exploits the beneficial effects of making the slender vault collaborate with a more rigid single deck, resulting from joint closure. Moving in the opposite direction, the second alternative considers the application of seismic isolation to the original scheme. An intermediate Isolation System (IS) has been postulated, inserting rubber devices—High Damping Rubber Bearings (HDRBs)—below the deck, at the top of the cross-walls. The advantages of an IS are clear, observing a great reduction of base reactions; moreover, the introduction of the IS completely modifies the original static scheme and exacerbates bridge deformability, at the expense of slender cross-walls, suffering for buckling. A comparison between these retrofit alternatives is argued in the article, evaluating the impact of different types of solution on the valuable original structural scheme.

Keywords:

• structural safety
• retrofit approach
• seismic isolation
• deck strengthening
• existing concrete arch bridge; Mallairt-arch-type bridge
• seismic vulnerability

Acknowledgements

The support provided by the consortium ReLuis is acknowledged. Bridge data are courtesy of the Società Autostrade Meridionali (SAM), represented by Dr Giulio Barrel, Managing Director. For the historical documents, thanks are due to the Associazione Italiana Tecnico Economica del Cemento (AITEC), and Professor I. Giannetti from the University of Roma Torvergata.

Disclosure Statement

No potential conflict of interest was reported by the authors.

Data Availability Statement

Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.

Declarations

This work has not been published previously, it is not under consideration for publication elsewhere, and its publication is approved by both authors. If accepted, it will not be published elsewhere in the same form, in English or in any other language.

Additional information

Funding

This work was supported by ReLuis_WP15_ISOLAMENTO_DeLuca, CUP E66C1900019000.