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composite structures; dynamics; fatigue
The Almas Tower is a 360 m high office tower in Dubai, UAE. The design comprises two intersecting elliptical towers located on a sculpted three-storey podium. The architectural form and client's requirement for floor efficiencies of 80% resulted in significant challenges for the structural design team. This paper discusses the structural framing adopted, wind-tunnel studies undertaken - including building acceleration, lateral movements and column-shortening effects - and mitigation measures introduced. It also describes the design of the tower's spire, which features tuned mass dampers.
The Dubai Multi Commodity Centre's Almas Tower is a 360 m high slender office tower located in the Jumeirah Lake Towers development in Dubai, United Arab Emirates (UAE) (Figure 1). The building consists of five basements, two podium levels, 60 storeys of offices and three mechanical floors. It has a total floor area of approximately 85 000 m2.
A typical tower floor plan is in the form of two diagonally offset ellipses, with a floor plate approximately 64 m long and 42 m wide (Figure 2). The floor plan from level 53 to level 64 consists of only one of the two ellipses. An 81 m slender spire peaks at 360 m, forming the highest point in the development.
The building was completed in September 2008 and according to the Council for Tall Buildings and Urban Habitat (CTBUH), was the world's second tallest building completed that year.
Structural system
The following constraints had a significant impact on the structural design of the tower and were considered at concept stage design
* the office floors to have an efficiency of not less than 80%
* flexible column-free and wall-free office space
* final sellable area to be within ±2.5% of the area sold by the client to ultimate office owners
* each office floor to be capable of supporting a 2.5 t safe placed anywhere within an office space.
The principal structural framing consists essentially of a tube-in-tube system. This is made up of a reinforced concrete peripheral frame and a central core wall which are connected to each other by central spine beams on each floor and outrigger walls at service floor levels.
A parametric study of the effectiveness of different arrangements of the external...