Willis Tower Skyscraper and the Glass Ledge

Willis Tower, formerly christened ‘Sears Tower’ is a centre of business and the tallest skyscraper in Chicago, Illinois, United States. Chicago’s skyline owned Willis Tower as the world’s tallest building until the inauguration of the Burj Khalifa in Dubai, U74AE. Currently it is on the second place among the world’s tallest buildings, is the tallest skyscraper in the western hemisphere and the tallest building in the United States.

Willis Tower has 108-storeys and stands at 1,450 feet (443 meters) - 1,730 feet (520 meters), which include the heights of twin antenna towers. The Tower offers 3.8 million square feet of space inside for retail and business purposes; and it cost more than $150 million to create this building.

Salient Features:

• The structure is formed from 9 bundled square tubes, each 75 feet wide with no columns between the core and perimeter. Two of the tubes are 50 floors high, two are 66 floors, three are 90, and two are 108.
• The construction with separate tubes provides lateral strengths to withstand the strong Chicago wind loads, as each tube only needs to take a part of the pressure.
• Facades consist of 28-acres of black anodized aluminium panels and approximately 16,100 bronze-tinted windows.
• Six roof-mounted robotic window washing machines are used to clean all 16,100 windows.
• The tower has a pressure lock at the freight entrance to combat the 'stack effect' generated by the differential in air pressure caused by cold air meeting warm air in the building.
• Includes world's fastest observatory elevators at 1600 feet per minute.
• Solar panels on the 90th floor roof of this tower are used to heat water for restrooms.
• Smart lighting systems installed here will automatically dim when enough sunlight is available inside.
• Includes 25,000 miles (40,223 kilometres) of electrical cable and approximately 43,000 miles (69,200 kilometres) of telephone cables.

Skydeck

The most attractive feature of the Willis Tower is the observation deck, or the “Skydeck”, which is 1,353 feet (412 meters) high above the ground. The Skydeck occupies the 103rd floor, the highest non-mechanical floor in the building. It has its own entrance on Jackson Boulevard, and attracts approximately 1.5 million visitors per year.

Skydeck offers the best views of Chicago and it is possible to see four states - Illinois, Indiana, Michigan and Wisconsin, as the range of view is 40 - 50 miles (65 - 80 kilometres) from here.

Another attraction at the Skydeck is 'the Ledge', a glass balcony extending 4.3 ft from where one can look straight down. The glass balcony is 10ft high and 10ft wide, and can hold five tons of weight with its 1.5 inches-thick glass. The transparent walls, floor and ceiling leave visitors with a feeling of floating in air.

Each glass box is comprised of three layers of glass laminated into one seamless unit. The low-iron, clear glass is fully tempered and heat-soaked for durability. In addition, the motorized system that projects and retracts the boxes from the building utilizes steel Linear Beams.

This Skydeck is cold, almost icy to the touch and gives a rather eerie feeling when looked at!

Trump International Hotel &Tower - A Sense of Glass

Trump Tower Dubai, or The Palm Trump International Hotel and Tower, is slated to be the jewel in the crown that is the Palm Golden Mile – a man-made island, located on the trunk of the Palm Jumeirah in Dubai.

This iconic building is the Trump Organization's first project in the Middle East and has been designed by Atkins architects. This tower will also be among Dubai’s greenest constructions.

Standing at a height of 270 metres, this 62-storey skyscraper hosts a luxury hotel, exclusive residential apartments, a three-storey entrance lobby, boutique offices, a swimming pool, restaurants, a dramatic sky lobby suspended high above a beautiful park, a business centre and so on.

With the ‘split-linked’ design, the towers stand on a four-storey bisected podium structure that houses the main car parking facility. At the tips of the two asymmetric elements sit twin sets of glazed, diamond shaped pinnacle structures that embrace the restaurants and sky bars. A spacious triple volume lobby is suspended between both towers above the park. This lobby is encased within a clear, light weight glazed roof, which gives it an exotic look.

Façade

The façade is nothing short of an awe-inspiring marvel in clear and tinted glass, white and silver aluminium panels, coloured granite and marble-faced blade walls and stainless steel. The vertical spacing of the façade will be based on the floor-to-floor height of 3.6m while the horizontal spacing will be based on a combination of the structural grid and the widths of the bedrooms and living areas to achieve a maximum number of vision bays for each room. Balconies have been restricted to the narrow ends of the floor plates only, allowing the external skin on the main façade to remain part of a sleek and smooth, glazed curtain wall.

Residence Collections

There are 3 collections of residences that have been designed in and around the south towers, namely Platinum, Titanium and Pinnacle collections. These residences incorporate ultra-premium kitchens and baths with finest European cabinetry, appliances and fixtures.

Viewing desk and restaurants are situated on the topmost floors of both towers and these will be designed as multi-volume, glazed spaces which will encompass dinning and viewing galleries. This Hotel & Tower will be expected to be completed by the summer of 2011.

Enamelled Glass

During the seventeenth and eighteenth centuries, the use of enamels became widespread, replacing the old methods of coloring glass - pot metal, flashing, and staining. Colored enamels seldom have the brilliance of pot-metal glass but can take on a rich translucence when carefully applied. Enamels are compounds of ground glass and oxides that become fairly transparent when heated and fused to clear or white glass.


Enamels are soft powdered coloured glass that are mixed with a medium and painted onto the glass with a brush. Deposits of special mineral pigments on the glass surface which vitrify at the annealing or tempering temperatures are stable, non-biodegradable deposits, and can be produced in one or more colours, and in different figures (tips, letters, and pads). When the medium is dry, the glass is placed in a kiln for firing.

Enamelled glass is tempered or heat-strengthened glass, one face of which is covered, either partially or totally, with mineral pigments. In addition to its decorative function, enamelled glass is also a solar ray controller.

Manufacturing Process

Glass is covered by some metallic oxide, and rendered opaque by the presence of arsenic trioxide, or an equally fusible transparent glass, mixed with some opaque infusible powder. It is always applied as a pigment, and is fixed to the glass background by heat. It is essentially a glass, and by heat should become partially incorporated with the glass upon which it is painted.

Applications

Enamelled glass can be used both internally and externally. Externally it can be used for overhead glazing such as in canopies. Internally it can be used for wall cladding and furniture and is particularly useful where resistance to humidity is required. Enamelled glass is used for glazing and for cladding in facades and roofs. Enamelled glass is also used in insulated spandrels or cladding panels in non-vision areas for an aesthetically clean appearance. It can be assembled into laminated glass or glazed insulation.

Flickering Exterior of Burj Dubai

Burj Dubai – Spoken of as the tallest man-made skyscraper ever built, is under construction at Downtown and is likely to be unveiled to the world by the end of this year. At present, this structure stands at a height of 800m. This, however, is not its final dimension - which will be revealed only upon completion of construction.

The exterior cladding of Burj Dubai, developed by Emaar properties PJSC, was completed recently. The façade of this building is made up of aluminium and glass. The total weight of the aluminum used is equivalent to that of five A380 aircrafts. In May 2007, Arabian Aluminium Company in association with Hong Kong based Far East Aluminium began work on the exterior with more than 380 skilled engineers and on-site technicians.

On the whole, 24,348 cladding panels have been used over a total curtain wall of 132, 190 sq m. The last cladding panel numbered 24,348 with a weight of 750 kg. This was installed at the height of over 662m. The total 103,000 sq m of glass used in the cladding panels can cover 14 standard football pitches, while the15,500 sq m of embossed stainless steel used can cover 34 National Basketball Association specified basketball courts. The cladding material was specially made using advanced engineering techniques. Cladding includes high-performance reflective glazing, aluminium mullions and textured steel spandrels with vertical stainless steel tubular fins.

Doubly glazed and factory sealed panels of more than 18 different strength specifications and over 200 sizes have been used. The panels are of varying thicknesses and each feature two glass pieces of about 8mm to 12mm thickness, buttressed by a 12 mm spacer for strength and resilience. The length and thickness of each panel depends on the height and the location where the panel is to be fixed. Also, the strength of a panel needs to increase with an increase in altitude. Hence, panels at higher altitude are strengthened with stainless steel in addition to aluminium.

At the initial stages, 20-30 panels were installed per day. This number was eventually increased to 175 panels per day. As the altitude increased, the workforce faced grave risk; to minimize which, curtain-walling for the spire was pre-installed on the ground and then lifted to the summit as secured.

A “flickering cladding” was designed to maximize resistance to heat from the sun. This is expected to minimize load on air conditioning systems, thus improving the energy efficiency of the tower.

18 window-washing units have been built to ensure cleanliness of this huge façade. These are built using 9 track-mounted telescopic cradles, each with an extendable arm which can reach out to a distance beyond 20 meters.

The observatory deck on the 124th floor has been named “At the Top”, and will present to visitors with information on the “History and Evolution of Dubai and the Burj Dubai” and also a view of the whole city. This structure is expected to be a benchmark for high-rise developers in creating environment-friendly, sustainable and futuristic buildings.