Ministry of Land, Infrastructure, Transport and Tourism/Promoting the use of wood in public buildings/Confirming the applicability of CLT wing walls to RC members
Structural frame image of trial design (from Ministry of Land, Infrastructure, Transport and Tourism materials)
As part of promoting the use of wood in public buildings, the Ministry of Land, Infrastructure, Transport and Tourism has confirmed structural safety when utilizing a construction method that uses CLT (cross laminated timber) panels for the wing walls among the structural members of RC buildings. . A trial design of a medium-sized government building that adopted the "CLT wing wall (National Research Institute type)" based on the experiment and analysis verification of the National Institute for Land and Infrastructure Management (NILIM) was carried out, and the structure evaluation was obtained from the Building Center of Japan. We also organized and announced points to keep in mind when designers refer to trial designs.
The Ministry of Land, Infrastructure, Transport and Tourism's Secretariat Office Building and Repairs Department is considering various wooden construction methods that can be used in public orders. Several trial designs were carried out, such as a mixed structure of wooden and non-wooden structures, and a "woody hybrid structure" that realizes wooden structure for each member. Based on the results, structural planning and cost issues are verified.
As one of them, we have summarized the results of the trial design of the CLT wing wall. Acquired a plan-limited general rating regarding the structural design method based on the retained horizontal strength calculation in the structural calculation using a commercially available integrated structural calculation program. With the structural safety and other factors, the groundwork for public orders has been laid, and it is expected that it will be used in the future, including local government orders, as a powerful method of converting a part of the RC structure into a wooden structure.
The trial design assumes a medium-sized government building with a total of 4 floors and a total of 3,000 square meters. A 210 mm thick CLT panel made of Japanese cypress was used for the wing walls. According to a trial calculation, the cost will increase by about 11% compared to the case of pure RC construction.
We also summarized the points to keep in mind when designers refer to trial designs in actual public orders. It should be noted that the trial design uses an analytical model based on structural experiments under certain conditions, and that the structural evaluation was obtained only for the plan. When conducting structural calculations with reference to the analytical model used in the trial design for building confirmation, it is also required to consult with a building official in advance about the appropriateness of the calculation.
