International Library of Children’s Literature

Site Plan. Adapted from Tadao Ando Architect and Associates.

Solutions INCLUDE:

BACKGROUND

The International Library of Children’s Literature (ILCL) is housed in what was previously known as the Imperial Library of the National Diet Library system, and was the first library in Japan to be retrofitted using seismic base isolation technology. This brick structure was originally constructed in 1906, during the Meiji era, and received an addition in 1929 during the Showa era. It is one of few remaining Western-style Meiji buildings in Tokyo. It is located in an area that contains a number of culturally significant historic buildings. In 1998-2002, it was renovated to meet updated fire code and disaster prevention standards. Tadao Ando and Nikken Sekkei Engineers developed the design of the renovation and a glass addition which redeveloped egress paths as well as adding floor area to the building.

The new addition emphasizes the historic parts of the building by providing contrast, while adding valuable function. Photo by Mitsuo Matsuoka.

Exterior becomes interior, and the brick facade becomes an entirely different experience in its preservation. Photo by Mitsuo Matsuoka.

The modern façade acts as a display case for the historic masonry within—an example of how new construction can support historic preservation. Photo by Vicky Klieber.

VULNERABILITIES AND STRENGTHS

The brick building of ILCL has a relatively simple geometry. A survey carried out prior to the retrofit showed that it did not meet fire code or seismic standards. The wood roof trusses of the Meiji-era were structurally lacking according to the seismic code, although they exhibited durability. Since seismic isolation was used, there was no need to strengthen the above-ground portion of the building, and much that was existing could remain. The largest challenge was that the layout of the building did not provide adequate egress, leading to the unique solution of adding a glazed passage.

Floor plans, adapted from plans by Tadao Ando Architect and Associates.

RETROFIT TECHNIQUES

Nikken Sekkei installed 69 laminated rubber isolators and 52 lead dampers on the basement level of the building. The isolators support the building load and insulate it from the ground, while the dampers absorb vibration energy. These devices reduce shaking in an earthquake by one-third to one-fifth. As part of the renovation, a glass volume was added to create a main entrance and cafeteria, and to link spaces within the existing building, improving usability of the space. The new volume adds light and creates a dialogue between old and new, without sacrificing the original façade.

OUTCOME AND IMPACT

The ILCL experienced an upper 5 quake in the Great East Japan Earthquake of 2011. While occupants felt a slow shake and a few books fell, the library opened normally and was available for continued use after the earthquake. The seismic isolation strategy allowed the appearance and layout of the original brick building to remain unchanged, while the glass addition provided added function. This project demonstrates using construction of an addition to increase value and floor area, while also allowing the preservation of a cultural gem that provides a service to the public. Life-safety and architectural impact are hand-in-hand on this project. However, it also uses one of the most costly seismic retrofitting techniques (base isolation)