Chillon Viaducts

Chillon Viaducts

informations
Introduction

The Chillon Viaducts have been reinforced by an Overlay of Ductal® UHPC. Thanks to its mechanical characteristics and its durability properties, Ductal® was the only material able to provide an efficient retrofitting preserving the bearing capacity of the bridge, a lower maintenance cost and a quick retro commissioning of an important axis of the Swiss highway network. The two Chillon Viaducts are among the most spectacular infrastructure works of the Swiss highway network. Ductal® was prescribed for the reinforcement of the two decks (2.2 km long by 12 m wide each). The implementation of thin layer of Ductal® (4 cm thick) with rebars, allowed the strengthening of the bridge decks for shear loads, bending, and fatigue while ensuring the waterproofing of the surface.

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Challenge

Description

Structural studies on the bridge bearing capacity showed that the main failure mode at Ultimate Limit State (ULS) is punching of wheel loads of heavy trucks through the 18 cm thin deck slab, though structural safety requirements currently can be fulfilled. Further investigations revealed that the concrete is prone to alkali aggregate reaction (AAR) due to its proximity to the Lake of Geneva. These assessments lead to the conclusion that the deck slab should expect a significant concrete strength reduction in the future, with an associated reduction in punching shear resistance. As the replacement of the waterproofing on the deck slabs was planned for 2014-2015, its combination with a strengthening intervention was investigated. Several options have been studied but none were fulfilling all the structure constraints: conventional concrete overlay was too thick with a lower durability, metallic structure was difficult to install because of the confined workspace of a box girder and did not offer a shield against environmental threats.

The final study has been decided to consolidate the viaduct by adding, on the previously hydro-jetted top surfaces of deck slabs, a 40 to 50 mm thin layer of Ultra High Performance Fibre Reinforced Concrete (UHPC) which is additionally reinforced by steel rebars, on the top surface of the deck slab.

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Description

Description

This project is one of the biggest overlay project in the world right now, with industrial quantities of Ductal® cast per day (up to 80 m3), over several weeks (6 in 2014 and 5 in 2015) to reinforce a twin 2.1 km long highway viaduct on a 53000 m² deck slab. Exceptional execution methods developed for this project have demonstrated the efficiency of the reinforced UHPC strengthening solution. The strength of the established formula has reduced the risks during the construction, particularly the workability of UHPC with the summertime temperature. Combination of UHPC with rebars offers an efficient way to produce highly durable reinforced UHPC tensile membranes to reinforce existing structures.

This intervention also improved the overall structural capacity of the bridge which allowed the increase in traffic +10% in 3 years, over 50,000 vehicles per day.

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Grafstal road bridge

Description

The concrete of the abutments and central pillars of the Grafstal road bridge (municipality of Lindau) above the A1 motorway showed damage due to chloride infiltration.

Infrastructure

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Eastbourne Arndale Centre

Description

Eastbourne Arndale Shopping Centre is a £85 million redevelopment including 22 retail units, seven restaurant units, a multiscreen cinema and a significant extension to the multi-storey car park.

Infrastructure

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Nipigon Cable

Description

The new Nipigon River Bridge east of Thunder Bay, Ontario is the first cable-stayed structure on the Ontario TransCanada Highway system. The project started in 2013 on this four-lane, two-span bridge which will replace an aging, two-lane structure. The new bridge has three precast concrete towers with cables supporting a 252m bridge deck and separate sidewalk for pedestrians. The center pier reaches a height of 51m above the bridge deck.

Infrastructure

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Gardiner Expressway

Description

The Gardiner Expressway structure rehabilitation is part of the City of Toronto’s Strategic Rehabilitation Plan in order to rehabilitate and keep the structure in a safe and operable condition for now and the future.

Infrastructure
Dé forma al futuro.
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