Nail Laminated Timber Floor Vibration Test Conducted at FFPRI

Shawn Lawlor

By: Shawn Lawlor

Managing Director, Canada Wood Japan/COFI Japan

In collaboration with the Japan 2×4 Home Builders Association, COFI continues development work on Nail laminated timber (NLT) assemblies. Aside from structural and fire-resistive considerations, floor vibration is another important factor to evaluate the mechanical performance of floor diaphragm when the occupants walk on it.  Under the supervision by Professor Dr. Yutaka Yokoyama of the Tokyo Institute of Technology, floor vibration tests were conducted to SPF NLT on September 18, 2020, at Forestry and Forest Products Research Institute in Tsukuba City.

A 6.0m x 5.5m NLT floor specimens was built in an open-air courtyard in the institute with 2×8 SPF.  Deflections and vibrations were measured under vertical loads applied by a hammer and by humans walking on the floor surface.  After measurement by the accelerometer, all witnesses of the test were asked to participate in the sensory evaluation test.  In this test, respondents were asked to stand at the floor diaphragm centre and to answer how much impact she or he felt by choosing a rank out of four when the Ph.D. candidate walks on the floor. The test data results will be used to develop optimized floor diaphragm span guides to guide NLT construction in large scale structures.