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Midsummer Night's Dream

On July 17, the plan for the construction of the new National Stadium with a total construction cost of JPY252 billion was withdrawn, going back to square one. The plan will be reconsidered with the intent to reduce construction costs. The area planned for the stadium is in Sendagaya, and it is to be used for the 2020 Tokyo Olympics and Para Olympics. The demolition of the existing structures has been completed in preparation for the construction of the new stadium and the land is being leveled. Those involved in the gas and welding materials industries can but give a sigh regarding the disappearance of 450 tons of welding materials.


How much steel and welding materials have been used in the major, large structures constructed in Japan recently? Tokyo Sky Tree constructed in Asakusa, Tokyo was constructed with an investment of JPY140 billion. According to a person in the steel industry, “The amount of steel used came to 36,000 tons, and it is estimated that 548 tons of welding materials were used.” Although we have now gone back to square one, if the new stadium had been constructed as planned the scale of the demand for gas and welding materials was anticipated to be second to that of Tokyo Sky Tree. Although the plan of the national stadium became a Midsummer Night’s Dream, the construction cost of the stadium, which finally came to be estimated at JPY252 billion (excluding the mobile roof), had been initially estimated at JPY130 billion.


The initial plan invited contractors to be respectively engaged in one of 3 construction areas of the National Stadium, being the main section including stadium building itself and the commercial facilities, as well as the keel arch section and the roof section. 3 prime contractors are suspected to obtain the orders. First of all, the amount of steel to be used in the construction of the main section of the stadium was estimated at 9,700 tons, with the volume of welding materials estimated at 145.5 tons. The amount of steel to be used for the section of the 2 keel arches was to amount to 9,300 tons, with 139.5 tons of welding material to be used. The roof section was to use 11,000 tons of steel and 165 tons of welding material. 30,000 tons of steel and 450 tons of welding material were planned to be used in the construction of the stadium. For each of the sections to be handled by the contractors, primary and second tier subcontractors were planned to dispatch specialist technicians, with the construction to proceed along this way.

To support the 2 huge keel arches as planned, a basic structure called a diver made of reinforced concrete joining the two ends of the arch was planned to be set up and under it an earthquake proof facility to be installed. For installing the arch section, a very difficult operation was forecast. At the construction site of the stadium a temporary welding workshop was expected to be installed, where the steel was anticipated to be welded in a complicated way. Finishing was to be done on the block parts of the steel frame structure. Welding would be done while dangling the structure in the air with a crane. When splicing together by welding, millimeter precision was anticipated to be required to prevent thermal strain. Those in the industrial gas and welding material industries held great expectations for the original plan to support the large movable roof with 2 keel arches, and to construct the new stadium within this.

(Photo: Proposed stadium site for 2020 Tokyo Olympics and Para Olympics)


18 Sep. 2015

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