Taiwan-Japan Cooperation – Full-Scale Grid-Purlin System Test

Participants from NCREE, Tokyo Tech, and Kyusyu-Daiichi Engineering Co., Inc.

In February 2018, National Center for Research on Earthquake Engineering (NCREE) signed a Memorandum of Understanding (MOU) with Tokyo Institute of Technology (Tokyo Tech) to promote bilateral cooperation in science and technology development on earthquake engineering research and education, and to further strengthen the relations. With this MOU agreement, NCREE supported Tokyo Tech consortium on a full scale test of roof beam braced with grid-purlin system in July 2018. This test was conducted by a team from NCREE led by professor Keh-Chyuan Tsai, in collaboration with Tokyo Tech and Kyusyu-Daiichi Engineering Co., Inc. (九州第一工業株式会社) led by professor Toru Takeuchi.

Grid-purlin system test setup in ABRI

The long-span spatial structures are commonly used as school gymnasium roofs in Japan. Past design assumes the roof as rigid diaphragm which is not realistic, since vertical responses are excited even under horizontal ground accelerations. After the Kumamoto Earthquake in 2016, damages on roof supports, and fractures of traditional braced roof members were reported. However, the grid-purlin system exhibited relatively less damages due to its high in-plane strength and stiffness. The beams of grid-purlin system are strengthened by steel grids by welding the steel grids and beam together. The grid-purlin also provides roof beams sufficient lateral supports to ensure full flexural strength can be developed. In order to confirm the seismic performance of grid-purlin system, a full-scale cyclic loading test was conducted in the Architecture and Building Research Institute (ABRI), Ministry of the Interior.

The test program commenced on May 28th, 2018. Two 13m long, 6.5m wide specimens were fabricated in Kyusyu Japan and shipped to Taiwan, then assembled by both Japanese and NCREE technicians in ABRI. The specimen contained main roof beam with two pinned supports, the gird purlin, and the boundary supports that served as inflection points of roof structure. Cyclic vertical loads were applied at beam end to access the vertical responses of roof. Test results suggest that the steel grids provide sufficient out-of-plane stiffness and strength, and also provide lateral support for the roof beams to develop full flexural capacity with sufficient ductility. This remarkable seismic performance is essential for Japanese design practices for adopting the grid purlin system as roof structure in future construction projects.

The test program ended on June 22nd. During the one month collaboration with Tokyo Tech, NCREE not only supported for experiment resources and shared experiences on large-scale tests, but also acquired the latest test techniques and adopted seismic design philosophy from Japan. The research relations between Taiwan and Japan have been much strengthened with the MOU agreement now in place. Tokyo Tech and NCREE will continue this research collaboration in future.

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