Steel frame erection work begins on the ground floor of Torch Tower

 Torch Tower will be the tallest ultra-high-rise building in Japan, featuring large-scale offices with standard floors of approximately 6,600m2, large-scale commercial facilities, an observation facility, residences, an ultra-luxury hotel, and a hall with a capacity of 2,000. A large plaza of approximately 7,000m2 will be located in the center of the block. Since construction began in September​ ​2023, demolition of existing facilities and construction of Torch Tower 's underground space have been progressing.

The diagonal steel columns are part of the "diagrid structure" that supports the approximately 385m high ultra-high rise building, and the triangular frame made up of the diagonal steel columns and steel beams suppresses the shaking of the building during earthquakes.

Mitsubishi Mitsubishi Jisho Design has been working on the structural planning and design of Torch Tower for over 10 years, aiming to rationally construct a 400m-class super-high-rise building in earthquake-prone Japan. As a result of this work, the main component of the newly developed structural plan ("external shell seismic control," Damped braced tube) is the newly developed "diagrid frame." To this, SHIMIZU CORPORATION Corporation has added technical development aimed at realizing the construction, and as a result of combining the ideas and technical capabilities of the two companies, the tower is finally on the verge of becoming a reality.

While typical skyscrapers have structures made up of vertical and horizontal columns and beams like a jungle gym (frame structure), Torch Tower 's "external shell seismic control" effectively positions diagonal members around the building's perimeter, turning the entire building into a single tube-shaped structure to enhance its strength. The lower floors from the 1st to 9th floors are made of a "diagrid frame," while the upper part (base section) is made of a "braced frame + oil damper" structure, also made up of diagonal members, and the diagonal structure creates the overall look of the tower.

The diagonal steel frame, which runs continuously around the entire perimeter of the building, approximately 400 meters in circumference, reaching a height of approximately 52 meters, weighs approximately 11,000​ ​tons. It is one of the largest architectural structures in Japan, supporting over 40 % (approximately 320,000​ ​tons) of the tower's total weight (approximately 800,000​ ​tons). The diagonal steel columns used here have the largest cross-sections reasonably possible in modern architectural steel construction (fabrication and erection) (1.4m x 1.6m cross-section, maximum plate thickness of 90mm, maximum component weight of 28.4 tons). The plan calls for construction of the diagonal steel columns to begin at the northeast corner of the building, with the first section to be erected around October​ ​2025 and the fourth section (9th floor height) to be completed around February​ ​2026.

SHIMIZU CORPORATION Corporation will strive to ensure quality through precise construction, and will also work to further improve the efficiency of construction by addressing the biggest challenge in the construction of ultra-high-rise buildings: reforming communications and the flow of people and goods during construction.

[Reference]

■ TOKYO TORCH business overview
Block name: TOKYO TORCH
Project name: Otemachi 2-chome Tokiwabashi District Type 1 Urban Redevelopment Project (Implementer: Mitsubishi Estate Co., Ltd.)
Planned location: Otemachi, Chiyoda Ward 2 Yaesu-chome, Chuo-ku 1 Chome

■ Torch TowerSpecifications
Main uses: Offices, rental housing, hotel, hall, stores, parking lots, etc.
Size - Total floor space: Approx. 553,000 m2, above ground 62 Floor/basement 4 Floors, height approx. 385 m
Construction period -2023 year 9 Month~ 2028 Year (planned)
architectural design and construction supervision: Mitsubishi Jisho Design Ltd.
Construction -SHIMIZU CORPORATION Corporation