Located in Avcılar, a district in Istanbul, Turkey, the 110-meter DoubleTree by Hilton became the tallest all-steel building in Turkey when it completed in 2012. It was bestowed the “Best Steel Structure High-Rise Building” award by TUSCA in 2013. Originally envisioned as a 14-floor steel and glass auto showroom, the design quickly shifted to 27-floor hotel building that includes an indoor pool, fitness and business centres and restaurants.
|Bracing||steel frame||HISTAR® 460||Intumescent coating|
||HISTAR® 460||Intumescent coating|
|Floor solutions||S355 primary beams||composite beams||Intumescent coating|
Steel was chosen as the primary structural material, due to the high amount of seismic activity in the area. Furthermore, as the function and size of the tower changed during the construction process, steel columns reinforced with cast-in-place concrete were used in the basement and an overall refurbishment of the foundation was conducted. This gave the foundation the ability to accommodate the increased stress on the system, without sacrificing the construction work that had already occurred; this is another aspect of this project that could not have been achieved without the use of steel. The primary structure consists of HISTAR® HD columns with a 40 x 40cm cross-section. These columns can accommodate all the vertical loads and all horizontal loads, from earthquakes and wind, are supported by transverse bracing elements, which are also HISTAR® HD columns. The use of steel for the primary structure, instead of reinforced concrete, also allowed for a smaller worksite (only the backyard and parking lot were used), minimising the impact on the surrounding environment. Furthermore, the use of steel also contributed aesthetically to the design; the thin structural elements help provide the maximum views towards the Sea of Marmara and the Lake of Kucukcekmece.
ArcelorMittal Steel Sections
A total of 2 683 tonnes of steel was imported on site. All deliveries of the ready-to-erect steel occurred during the night times, which minimised disturbances to the surrounding area and interruptions in regular traffic. HISTAR® 460 Jumbo columns, S355 primary beams and bracing, and S275 secondary beams were used to assemble the structure, due to their flexibility and weldability. The column joints were prepared so that full penetration butt welds could be achieved on-site. The main beams and secondary beams were designed as composite floor elements, coated in concrete, which was an economic and efficient solution, in terms of the increased spans that were able to be achieved, the minimal amount of material used, and the reduced floor thicknesses. All beam-to-beam and column-to-beam connections were achieved using high-strength 10-grade steel bolts.
In order to achieve adequate fire resistance, all steel sections were coated with an intumescent coating. This was also used due to its aesthetic value, as the bracing elements are exposed in the hotel rooms, and the paint provides a clean, modern finish.