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Sayı: 39 - Nisan 2014


Golden Horn Metro Bridge Project

The Golden Horn Metro Bridge project which can be considered a first in Turkey in terms of architecture and technology was realized with the Gülermak Ağır Sanayii ve Taahhüt A.ş. and Astaldi Spa partnership of.

 <b>Place:</b> Istanbul
<b>Construction Duration:</b> 2009-2014
<b>Project Owner:</b> Istanbul Metropolitan Municipality
<b>Preliminary Structure Design:</b> Michel Virlogeux (France)
<b>Architect:</b> Hakan Kıran Mimarlık (Turkey)
<b>Structure Advisor and Structural Design:</b> Wiecon Consulting Engineers & Architects (Taiwan)
<b>Prime Contractor:</b> Astaldi Gülermak Ordinary Partnership (Italy-Turkey)
<b>Steal Manufacture and Installation:</b> Gülermak Ağır Sanayii İnşaat ve Taahhüt A.Ş. 
One of the mass transit rail system investments to create a transport solution for Istanbul, one of the most important finance and culture hubs and most crowded cities of Turkey and the world, the Golden Horn Metro Bridge project which can be considered a first in Turkey in terms of architecture and technology was realized with the Gülermak Ağır Sanayii ve Taahhüt A.ş. and Astaldi Spa partnership of. The construction of the bridge that was opened in February 2014, including the approach viaduct lasted 5 years. 
The project of 1000 m in length consists of 5 main parts including a Network Arch Bridge, a Drawbridge, Unkapanı and Beyoğlu Approach Viaducts and a simple suspension bridge. The Unkapanı and Beyoğlu Approach Viaducts were manufactured as multispan posttensioning reinforced concrete viaducts. 
The Drawbridge and Network Arch Bridge were designed and manufactured as high strength corten steel base orthotropic decks. Besides contributing to one of the solutions of Istanbul's transport problems with the network arch bridge system connecting the historical peninsula in the middle of the Taksim-Yenikapı Metro Route atop the Holden Horn to Beyoğlu, is also contributes to the reflection of the historical and modern face of Istanbul with the aesthetic appearance. 
Since the project is located right beside the historical peninsula the design was developed elegantly as possible and in line with the environment's texture. The number and height of abutments was determined taking in consideration every kind of ambient conditions. While posttensioning reinforced concrete viaducts deck heights change between 1.1 m in the open and 2.5 m in support areas, an elegant appearance that is aesthetically harmonious with the environment was achieved with the geometry of the deck and the openings of about 45 m were fit into these sections. In the same manner the optimum geometry was formed for the steel bridges, keeping the network arch towers as low as possible to conserve the silhouette of the peninsula. 
The Cable-Stayed Bridge and Drawbridge, was carried with a special pile system that goes up to 110 meters deep below the sea as a result of forage made after steel piles manufactured full size in Portugal which are 2500 mm in diameter and 40-45mm in wall thickness, are socketed into a rock. Despite the 110 m total height, the piles were manufactured by hammering with an average 50mm deviation horizontally with a high precision. 
The middle abutments carrying the two towers of the Network Arch Bridge are carried by nine piles, while Southwestern (Unkapanı) end abutment and the Drawbridge are carried with five each piles, and the Northeastern (Beyoğlu) end abutment of the Network Arch Bridge is carried by four piles. 
Due to the high weight of the pile heads below the pylons of the Network Arch Bridge and the abutments of the Drawbridge they were installed separately at the first stage. The pile heads of the end abutments on the other hand were installed together with the abutments. The pile heads weighing about 450 tons manufactured at Cemre Shipyard by Gülermak A.ş. in Yalova, were brought to Golden Horn by barge and were weld to the pile tops 3 meter below sea level by using the equipment comprised of the placement of the highest capacity crawler crane (LR1800) in Turkey on a barge. To be able to weld below sea level special dry docks were designed and manufactured for each pile. Everything performed in line with international standards. 
After the installation of the pile heads the 250 ton abutments of the pylons were lifted using LR1800 and were joined to the pile heads by full penetration welding. 
After the installation of the 27 meter first deck segments the pylons were installed in three segments. After this stage the decks of the bridges were installed by using the balanced console system. Four lifting gantries in total were placed on the two towers of the Cable Stayed Bridge, one in each direction and all of the remaining deck installations were performed with these gantries. 
While the installation of decks for the Cable Stayed Bridge were performed in sync with with the network arch cables with the balanced console system, the behaviors of the decks and towers, their locations in space, and their compatibility with the project were tracked at every stage; as a result at the 180 m Cable Stayed Bridge span the installation was completed with great accuracy with a maximum of 17mm vertical deviation. The biggest challenge at this stage was that the fluctuation between the day and night temperatures affected the measuring controls because the whole structure is made of steel. The controls were performed at the same time and about the same temperature every day to prevent mistakes. 
After the installation of the drawbridge abutment the cylinder system placed on the pot bearing, responsible for lifting the whole bridge before opening was installed. Master pivot cylinder was ten installed on this system. After the installation of root segments on the cylinder, two lifting systems were designed and with the same method lifted the 300 ton steel deck segments together with the walkways and after the adjustments were weld to each other. 
After the installation of the steel decks, to balance the consoles of different length and weight specially manufactured 300 ton steel balls were placed in the prepared reservoirs. After this stage the installation of the hydraulic and mechanical systems was continued. Then the installation of the lengthwise and widthwise interlock systems, rail interlock systems, and the pistons that will rotate the whole system 90 degrees on the master pivot were completed. In full automatic mode the is able to open and close in 6 minutes. 
After the deck installation was completed, platform girders, walkway railings, canopy bearer steels, emergency escape steel construction products, and overpass carriers were installed. Afterwards platform canopy coating, platform side surfaces and station aluminum zinc coating were completed. 
All steel manufacture was realized in line with the below listed specifications according to international standards by Gülermak and certified after being tested by independent institutions. 
Çelik Yapılar - Sayı: 39 - Nisan 2014

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