Kajima, a Japanese construction and engineering company, has developed a seismic damping system for timber structures that has completed third-party performance evaluation ahead of its use in the company’s planned Tohoku Branch Building in Sendai.
As timber is used in increasingly larger buildings, engineers continue to look for ways to strengthen seismic performance without reducing the material’s structural and architectural advantages.
The system combines timber construction with seismic control technology and is set to form part of the office building’s structural design.
Known as the Transom Seismic Damping System, the structure takes its name from traditional Japanese transom designs and uses seismic dampers within a timber frame.
New approach to timber seismic resistance
The system uses simple pin connections between timber columns and beams, with seismic dampers positioned between upper and lower beams. During an earthquake, resistance generated by the dampers is transferred as axial force through the beams, allowing the timber members to absorb and distribute seismic energy.
Kajima said the approach allows the timber members to make better use of their structural capacity while reducing reliance on rigid beam-to-column connections typically used in timber frame systems.
The company added that the technology can achieve seismic performance that meets the same design standards applied to high-rise buildings.
The system was also designed to keep timber elements visible in the structure. Kajima said the connections between the timber beams and dampers were simplified to support both construction efficiency and architectural expression.
Testing completed for flagship office building
Kajima performed structural testing on the system to assess its performance under seismic loading.
The company reported that the damping structure maintained stable energy absorption characteristics even under deformation levels beyond the design range. Testing also found no issues affecting the timber members or the connections between the upper and lower beams.
The technology is planned for installation along the central north-south axis of each floor of the Tohoku Branch Building. Timber framing will be combined with a steel structural core incorporating concrete-filled steel tube columns and steel beams.
For the project’s seismic design, Kajima adopted a time-history response analysis method, an approach typically used for detailed assessment of high-rise and base-isolated buildings. The completed performance evaluation found that the dampers reduce shaking amplitude and shorten the duration of residual movement following seismic events.
Sendai project to showcase the technology
The Tohoku Branch Building is planned on a 1,606m2 site in Aoba-ku, Sendai City, Miyagi Prefecture.
The project was previously announced as Kajima’s flagship timber building and is set to become the first to adopt the company’s Transom Seismic Damping System.
The office development will comprise one basement level and nine storeys above ground, with a total floor area of approximately 8,872m2.
The structure will primarily use timber construction, alongside selected steel structural elements, and is expected to incorporate around 1,800m3 of wood in its framework.
Kajima is responsible for both the design and construction of the building, which is scheduled for completion in 2029.
