Place Victoria's first tower
Lake Point tower is completed, the block will be the tallest in the world in reinforced concrete.
Conceived by Pier-Luigi Nervi in conjunction with Luigi Moretti, of Rome, the framing system is believed to be unique. It is based on a central spine made up of two perpendicular shear walls, diagonally in the core of the tower, running the full height of the building.
Four large exposed corner columns are joined to this central spine by powerful horizontal frames of rein- forced concrete at each of three mechanical floors, the 5th, 19th and 32nd floors. Two intermediate columns are introduced at each of the outer faces of the build- ing.
The floor system is flat slab construction with two- way ribs. Drop panels are provided around all columns. Slabs are 3 in. thick and the ribs 13 in. deep. In this way, all floors are free of wind forces, deflections are reduced to a minimum, columns do not work in bending so that under any condition of loading they remain in compression.
The external appearance features the reinforced con- crete nature of the structure by carrying the four main corner columns apparently externally the full height of the tower. At the main ground floor lobby area the con- crete work remains exposed to view internally on the massive columns.
The central core, in the area of the vertical shear walls, which is about 54 ft. sq.. houses the stairs, toilets. mechanical and electrical shafts, main boiler stack and other services. Twenty-two elevators grouped in six banks around this core serve the various sections of the tower.
The outer face of the building consists of an alumin- ium and glass curtain wall, E.G.M. Cape and Co., Ltd. are the general contractors.
Design and Construction of Prestressed Concrete Structures
Ar the 1962 Congress of the FIP (Fédération Interna- tionale de la Precontrainte) held in Rome and Naples, it was decided to set up a committee to prepare recom- mendations for the design and construction of prestressed concrete structures, under the presidency of Prof. C. Cestelli-Guidi of Italy.
At that time the CEB (Comite Europeen du Beton) after some ten years' work was completing its document containing recommendations for the design and construc- tion of reinforced concrete and had formulated safety pro- visions and the limit state philosophy of design, which it
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was agreed should be applied to prestressed concrete also. In fact, so much of the preparatory work done by the CEB was applicable to prestressed concrete that it was clear that very rapid progress could be made if a joint committee of the two organizations could be set up. The two Presidents, Monsieur Yves Guyon (FIP) and Prof. Franco Levi (CEB) agreed to co-operate in this way.
Delegates from 20 countries were appointed to the committee, the first meetings were held in Naples and working commissions were then set up.
During the past two years considerable progress has been made by the commissions and at meetings last year in Bellagio (Italy) and in London detailed recommenda- tions for design and construction were defined. It is hoped to have these recommendations finalized and pub- lished as an agreed text at the time of the FIP Congress in Paris this year.
Two important design criteria are adopted for pre- stressed concrete, depending on the type of structure he- ing considered, namely (a) fully prestressed concrete in which tensile stresses in the concrete are avoided at working loads and (b) partially prestressed constructions where tensile stress of different degrees may be permitted. In this way for structural concrete there will be a gradual change from fully prestressed concrete through partially prestressed concrete to reinforced concrete.
In the first place it is proposed to have separate documents each complete in themselves for reinforced concrete and prestressed concrete. There are, however, many sections of the documents which overlap and it should be possible to combine the documents and avoid much of the repetitive material in the future. This may be more appropriately achieved when the CEB Commis- sion considering precast concrete dealing with large panel construction has completed its recommendations.
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One of the latest additions to the London sky-line is this honey- comb block of offices just off Kingsway, designed by R. Seifert and Partners. The 16-storey cylinder gives a new look to the area and provides 195,000 sq. ft. of new office space. To avoid spoiling the famous corridor-look of Kingsway, the building is sited so that it is not visible from the thoroughfare itself. Sir Robert McAlpine and Sons, Ltd. are the contractors.
Far East Architect & Builder February, 1966
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