Schedule & Program

Organized Session
"Toward 2020: State-of-the-art Steel Structure Technologies for the Future of Tokyo"

In July 2020, Tokyo will once again host the Olympic and Paralympic Games, over half a century since the Games were staged here in 1964. Tokyo will also host the PSSC in November 2019 for the first time in 27 years. Since the PSSC was last held in Tokyo, steel structures in Japan, particularly in the capital, have continued to evolve, increasing in area, height and comfort. The choice of Tokyo to host the Olympics, in particular, has sparked interest in such structures in the construction and civil engineering industries, and the past several years have witnessed a proactive execution of new construction and reconstruction of Olympic facilities as well as infrastructure upgrades. Against such a background, the Organized Session will convene under the theme “Toward 2020: State-of-the-art Steel Structure Technologies for the Future of Tokyo” with speakers from leading businesses in the construction and civil engineering industries of Japan.

In connection with this session, the organizer will offer a technical tour to several Olympic-related facilities on November 11 (Monday).

9:00 to 10:30 (tentative)
Sunday, November 10, 2019
Digital Multi-purpose Hall, 2F


New National Stadium in Japan

Shinichiro Kawamoto
Taisei Corporation

The New National Stadium is a facility that is also used as the venue for the Tokyo Olympic Games and Paralympic Games in 2020. This stadium is hoped to become a place where all athletes can show their best performance, and to be loved and used frequently by people of future generations. Based on the concept of “Stadium in Forest”, the new stadium is open to everyone. Becoming a part of the forest of Meiji Jingu Shrine, it will form a green network spreading from the Inner Garden of Meiji Jingu Shrine to the Imperial Palace, and become a “new center of sports cluster” where everyone can enjoy taking walks and various types of sports.

In addition to the concept of “Stadium in Forest”, the structural design was proceeded on the themes of Japanese-style and world-class stadium, disaster-resilient stadium for improving the capacity of disaster prevention of the area, and so on. The structural design with thorough consideration for workability, especially for the construction method of the roof was proposed.

Various unique structural ideas were applied for this stadium, for example, the flat roof frames which coordinated with the surrounding environment and suppressed the height, the simple structure to keep the construction period, adoption of precast and prefabricated products for ensuring both the construction period and high quality, the cantilever roof structure of the hybrid members using lumber and steel, and the seismic response controlled structure based on Soft-First-Story Theory for high seismic performance.

Structural planning was advanced with a top priority to building the structural frame within the construction period, while achieving the basic concepts of the New National Stadium.

In this presentation, it will be reported the outline of the structural design which realizes the design concepts and which facilitates the construction sequence.


Structural Features and Construction of Olympic Aquatics Center

Yasuhiko Asaoka
Obayashi Corporation

Olympic Aquatics Center is swimming competition venue for Tokyo Olympic and Paralympic Games 2020. The footprint is approximately 200m in south-north (longitudinal) direction and 130m in east-west (transverse) direction. The building is 34m high, and 4 stories above ground and 1 story underground, consisting of main arena and sub arena. The main arena has main pool of 50m long and diving pool of 5m deep, and the sub arena has another pool of 50m for preparation at the time of Olympic and Paralympic Games.

The structural feature is represented by the roof covering the main arena, the sub arena roof and the perimeter columns around the main area.

The main arena roof is the steel trussed frame spanning 130m in longitudinal and 80m in transverse direction, giving column free space to main arena. The roof truss is erected at lower level for easy, safe and quick construction, and lifted up to the designed level.

The roof soffit is concaved by 1.5m at center, giving comfortable atmosphere. The roof truss is supported by two rubber bearings at four each corner cores, working as base isolation system.

The sub arena roof is featured by precast prestress concrete beam of 44m long, adding aesthetic sense to the sub arena. The concrete beam gives enough stiffness to the roof as entrance approach. The concrete beams are dived into seventeen units. These units are precast at fabricator and assembled at construction site and tied by prestress cables.

The perimeter column supporting grandstand is slender steel column covered with prestressed concrete to prevent from buckling and satisfy with fire and rust resistance, inspiring traditional Japanese style. The prestress is entrained to prevent cracks which reduce resistance against buckling.




The defining characteristic of this building is the wooden roof which reflects traditional Japanese wood culture.

The roof structure is the Composite Beam Strings Structural System. This consists of a 69.6m long beam strings structure supported by 9.6m long cantilever trusses on both sides. The total span (88.8m long) makes this amongst the world’s largest timber structure of its kind.

The top chord of the beam strings structure and the bottom chords of the cantilever trusses are arch shaped timber beams to take advantage of good compressive strength of timber. The timber beams are laminated wood made from Japanese larch. The bottom chord of the beam strings structure is steel cable to achieve an attractive and light weight inner appearance.

Beam Strings Structure can balance horizontal forces induced by its own self-weight within the beam structure itself. This helps to reduce the horizontal loads to the supporting frames.

During the erection, the lift up method is applied to benefit from shorter construction term and improved safety.

The beam strings structures are assembled on the ground before being raised up 30m high to the roof level. The lifting is being conducted in 5 times from September 2018 to March 2019.

Also, the slanting exterior walls are covered with Japanese cedar. We hope this building with the gently sloping wooden arch roof and warm atmosphere, will allow guests to experience traditional Japanese wood culture.


Ariake Arena - Seismically-isolated Large-Space Roof Structure -

Yuki Hamada
Takenaka Corporation

Ariake Arena is planned to be an indoor stadium as a venue of the Olympic and Paralympic Games Tokyo 2020, which has a main arena used for volleyball games that can accommodate about 15,000 spectators. After the Olympic and Paralympic Games, plans call for the arena as a venue for not only sports events but also concerts.

The main arena has a configuration in which the exterior wall upwardly opens outwards and the roof inside the arena is structured in a downwardly convex form. Under the restricted site conditions, certain devices are incorporated so that the air volume inside the main arena is minimized while securing the spectator capacity.

The main structure of the stand section is planned as a reinforced concrete structure with high stiffness from the viewpoint of preventing vibrations due to excitation caused by a great number of spectators.

For the core framing structure at four corners that carries the horizontal force of the roof section during earthquakes, a steel-frame structure is selected and planned to have sufficient redundancy in terms of both stiffness and strength.

In order to mitigate the danger of falling ceiling and suspended equipments during great earthquakes, a seismically-isolated roof structure is adopted in which the isolation devices are arranged just beneath the roof.

For the roof structure, the steel-frame plane trusses are used, which are composed of 22 main trusses and 7 connecting trusses arranged orthogonally to the main truss. The main trusses are arranged at 6-m spacing, with a truss depth of approx. 6.4 - 9 m, and a span of about 120 m.

Especially, the travelling construction method is adopted for the roof erection in which each steel-frame plane truss is assembled on the temporary platform, and then a large block of trusses are travelled in the orthogonal direction to the main truss.


Outlines of Large-Scale Renewal Projects of the Metropolitan Expressway and Technical Report on the Renewal Project for Route 1 Haneda Line

Shigeru Ihara
Metropolitan Expressway Company Limited

Large-scale renewal projects in 5 sections of the Metropolitan Expressway were promoted to ensure long-term durability and future maintenance management in 2014. The renewal project in the pier section of Higashi-Shinagawa and reclamation area of Samezu on the Route 1 Haneda line of the Metropolitan Expressway, which is the first case of its kind in Japan, have been already carried out since February 2016. In the presentation, the details of the renewal design and on-site work, including bridge reconstruction, in the Route 1 Haneda line as well as the outlines of 5 large-scale renewal projects will be explained.