Infrastructure

Peace Bridge

Tbilisi | Georgia

PROJECT DETAILS

City
Tbilisi
Country
Georgia
Customer
Tbilisi City Hall - Old City Rehabilitation and Development Fund (OCRD)
Architectural design
AMDL CIRCLE.
Period
2009 - 2010
Amount of works
11.500.000 €
Services Provided
Structure design
Sector
Infrastructure
Dimensions
Dimensions of the walkway: 160 x 4.80 m
Construction technique
Metal carpentry and cold bent glass

A symbolic architecture

A bridge is a symbolic piece of architecture: it not only fulfills the function of connecting two geographically separated places, but also represents an ideal; it is a monument celebrating the union between different cultures, ethnicities and countries.

The Tbilisi Peace Bridge, designed in January 2009 by architect Michele De Lucchi's firm, now AMDL CIRCLE, was strongly desired by the then President of Georgia, Mikheil Saak'ashvili, who inaugurated it in 2010. Its roof, a synthesis of a fruitful dialogue between architecture and engineering, appears as a single transparent and luminous leaf-shaped membrane.
The Peace Bridge is located on the Mtkvari River and connects the old Bericoni neighborhood with Rike Park, the "gateway" to the more recently built Tbilisi: at the point where the bridge rises, the river divides the western, the most historic and ancient part of the city from the eastern part, creating a sharp split in the urban fabric. The bridge reunites the two portions of the city, right at the point where camels traveling along the Silk Road crossed the river: it consists of a pedestrian footbridge 160 m long and 4.80 m wide in the central portion, formed by a slender metal structure and a sinusoidal-shaped roof made of steel lattice girders and glass plates. The roof behaves as a single lightweight, shell-like membrane under which the footbridge appears to be suspended: it is in fact anchored to the two banks of the river only by means of four fork pillars.

Tbilisi Peace Bridge night view - Georgia
Night panorama of Tbilisi Georgia with Peace Bridge
Side view Peace Bridge in Tbilisi - Georgia
Pedestrian walkway and glass and steel deck of the Peace Bridge in Tbilisi - Georgia

A Bridge for Peace

Tbilisi is a city marked by a recent controversial past and an extremely fragmented cultural, social and political framework: the capital of Georgia seeks a national identity and a role as a promoter of the country's economic and social revitalization also through investment in modern infrastructure and fine architecture, characterizing the landscape. The Peace Bridge is one such case: it encapsulates symbolic and cultural instances as well as practical and infrastructural needs, posing as a monument representing the union between past and present, between the city's historic core to the west and the new neighborhoods that have grown up on the bank to the east.

The bridge is an ideal continuation of Rike Park, accompanying pedestrians to the historic downtown core. But it is not just a transit element: at the center of the structure is created a plaza from which citizens can enjoy a privileged vantage point over the city. In turn, the innovative materials and sinuous forms make it a strongly recognizable element in the city fabric, as if it were a beacon, an element of orientation and identification.

Panoramic view Peace Bridge over Mtkvari River in Tbilisi - Georgia

Geometry and technology

The design arose from simple geometric concepts: the curve defining the extrados of the roof is generated by three tangent circumferences; on the curve defined by their union runs the vertex of a parabola with the concavity pointing downward, which defines the primary arches of the roof. Another curve, generated by five tangent circumferences, cuts the lower branches of the parabola and marks the desired shape.

The high seismic risk zone, the dynamic stresses due to the transit of people and the strong gusts of wind that characterize the area have imposed specific studies, carried out with careful and sophisticated analysis techniques, in order to determine the safety coefficients necessary to guarantee resistance toward such events.

Side view of Tbilisi Peace Bridge construction site - Georgia
View of Tbilisi Peace Bridge construction site - Georgia
Laying glass roofing panels Tbilisi Peace Bridge - Georgia
Detail laying glass roofing Tbilisi Peace Bridge - Georgia
Detail of glass panels covering the Peace Bridge in Tbilisi - Georgia

The metalwork was made from custom-cut, calendered and welded-together tubular round sections. Some portions were pre-assembled in the workshop: in order to verify the results obtained by calculation using the finite element method, load tests were carried out on prototype joints, made to a scale of 1:1.

The enclosure of the roof consists of a series of flat sheets of tempered and laminated glass, held in place by coupling devices placed in the gap between glass and glass, without the need for drilling, and sealed to the cavity. The glass was cold deformed, forming it on the predetermined surface by the primary metalwork structure, through the same connection mechanisms.
The assembly took place on a riverbank, and the launching was carried out through the use of two barges, on which the bridge was temporarily supported, to be placed in its final position.

View of Tbilisi Peace Bridge construction site - Georgia
Phases of placement Tbilisi Peace Bridge - Georgia
Phase 2 placement Tbilisi Peace Bridge - Georgia
At the structural level, the roof is a three-dimensional shell with a total length of 115,600 mm and a variable width: 12,400 mm in the central part and 22,000 mm where the supports are located.
Shell covering Tbilisi Peace Bridge - Georgia
The structure consists of the following structural elements: an edge beam of Vierendeel type, made of Φ 406x10 mm and Φ 406x30 mm tubes; main arches Φ 406x10 mm and diagonal and longitudinal tubes Φ193.7x10 mm and Φ193.7x12.5mm.
Every joint between the tubes has been welded: the parts are prefabricated on site and then assembled in situ. To facilitate prefabrication and minimize welding on site, at each junction the axes of the main arches and the diagonal and longitudinal tubes do not cross at the same point.
Tbilisi Peace Bridge Construction Site - Georgia
Construction time is another peculiarity of this major work, consisting of 500 t of steel. A careful study of the smallest details, a codified geometry, the use of pipes of only two diameters, and the connections between the nodes, welded in place, made the work proceed extremely fast, building the bridge in only 269 days, without accidents, disputes or price changes.
Tbilisi Peace Bridge Construction Site - Georgia
Rendering Tbilisi Peace Bridge - Georgia
"This new bridge is a symbol of Georgia's journey from the past to a better future."
Mikheil Saak'ashvili
Former President of Georgia

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