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Inspection of the landmark Polyfytos Lake Bridge of Servia

the 44 year – old and 1372 m – long bridge that connects the cities of Kozani & Larisa – Athens national road network

Introduction

The Lake Polyphytos Bridge or the Servia / Neraida High Bridge is the second longest bridge in Greece, with a length of 1,372 m designed by XEKTE SA and Prof Riccardo Morandi. Construction began in 1972 along with the artificial lake and was completed in 1975. The bridge has similarities* with the structural system of the Ponte Morandi (Polcevera Viaduct) that collapsed on 14 August 2018 in Genova.

The involvement of the infrastructuResilience group

After invitation from the regional Governor of Western Macedonia – Greece, a visual inspection of the landmark Lake Polyphytos Bridge (Greek: Γέφυρα της λίμνης του Πολυφύτου) at Servia, Kozani had been conducted with the Governor of Western Macedonia and his consultants in early January 2020. The #infrastructuResilience of the university of Surrey was there to offer consultation and opinion on the significance of what was told to be a vertical displacement of the deck, mainly along the part of the bridge that was constructed by the balanced cantilever method. The visual inspection revealed large vertical displacements of the balanced cantilever spans of the bridge, and thus urgent preventive measures were considered to be appropriate and taken at this stage. The measures are aiming at mitigating the risk of failure of the landmark and safeguarding the safety of end-users and citizens. The urgent measures are twofold: 1) reduction of maximum vehicle load and maximum speed and 2) connection of the Gerber simply support 40 m-long spans with the 30 m long cantilevers of the bridge. The first measure aims at reducing the load and the second will reduce the risk of having the Gerber beams unseated. However, the reduction in the risk is very small as the main issue seems to be the vertical deflection of the cantilever downward, and this is the main conclusion of the inspection, whilst the reduction of the maximum vehicle load and speed seems to represent a very small portion of the total load of the deck. The photographs below show left: a view of the bridge (from Kozani to Servia), middle: the visual inspection, right: the problem as confirmed on site.

In continuation to our involvement with the inspection of the High Bridge of Servia (Polyfytos Lake Bridge), Stergios spoke to the national tv channels ERT1 and ERT3 (@ time 1h35min)  analysing “what’s next” for this landmark bridge of high importance and how this affects the resilience of the network, the region and beyond.

Our involvement with the inspection of the bridge has been covered extensively by local and international media.

Press releases and reports:

tovima.gr     kathimerini.gr   ethnos.gr   ert.gr

zougla.gr    makthes.gr msn.com  greekcitytimes (en)

eleftherostypos.gr neoskosmos.com (Australia)

kozaniTV

* The similarity is the use of Gerber simply supported spans on cantilevers. Also, the understanding is now that the preliminary interview, on 15 August 2018, one day after the collapse of the bridge (see Stergios’s BBC interview here) has provided a relatively accurate comment: “…some environmental factors may have caused this bridge to deteriorate early… rust can be seen at the top of the tendons” is in accordance with the detailed research published 16 months later by Calvi et al. (2019): “The loss of a stay seems to be the final cause of collapse…The possible initial cause of the collapse may thus be related to fatigue problems in the tendons near the tip of the antenna, or by deterioration of the connection between stay and transverse link.” The latter raises concerns with regard to the design of the system of protection of the tendons adopted by professor Morandi.

In continuation to Stergios involvement with the High Bridge of Servia (Polyfytos Lake Bridge),  Stergios will be talking to the national tv channels ERT1 (14 Jan, after 7am-GR time) and ERT3 (14 Jan, after 11am-GR time) analysing “what’s next” for this landmark bridge of high importance and how this affects the resilience of the network, the region and beyond.

Stergios participated today in the examination of a PhD dissertation at Imperial College, on the design of externally prestressed timber bridges. Very interesting topic and impressive work. Thank you Christian Málaga-Chuquitaype for the invitation.

Stergios was invited by Prof E Chatzi and delivered a lecture on “Risk and Resilience of Bridges and Networks” at ETH Zurich-Institute of Structural Engineering, followed by interesting discussions and exchange of ideas on resilience assessment challenges!

Stergios and Dimitra had a fruitful meeting with Dr Annika Baier and Dr Fabien Choffat in the headquarters of SIKA AG in Zurich. The future trends of bond technologies for FRP measures were discussed with the industrial partner of Briface H2020-MSCA-IF project.

Stergios is giving an invited lecture on “Risk and Resilience of Bridges and Networks” at ETH Zurich-Institute of Structural Engineering on Monday 21st of October.

Abstract: The exposure of bridges and transportation networks to natural hazards is proven to have severe consequences on world economies and societies. Therefore, risk and resilience assessment of these assets to extreme events and sequences of diverse hazards is of paramount importance for maintaining their functionality and continuous operation even after severe natural and human-induced hazards. In this context, engineers, consultants, owners and operators would be benefited in the design, assessment and decision-making process from quantifications of risk and resilience. This quantification should account for the sequence of hazards, the type and extent of damage and impact in bridge or network functionality, the latter expressed by robustness, and the importance of the asset, the available resources and priorities, including the rapidity and resourcefulness. This lecture will provide a systematic introduction to the concept of risk and resilience assessment of bridges and transportation networks. Examples and practical applications will be presented to illustrate the main components of risk and resilience, i.e. hazard actions, typology of bridges, damage modes, fragility/vulnerability analysis, loss assessment (direct/indirect), restoration, mitigation measures and decision-making for networks.