SPF Horizontal Diaphragm Tests in Progress

Shawn Lawlor

By: Shawn Lawlor

Managing Director, Canada Wood Japan/COFI Japan

In the Japanese traditional P&B housing industry, more and more structural designers prefer using SPF dimension lumber for roof rafters and floor joists.  This is because dimension lumber is easier to handle and to procure compared with the conventional Taruki and Neda.  COFI has been providing an Excel-based structural design tool for the use of SPF dimension lumber in support of technical inquiries from designers.  The cumulative number of users of this Excel-based design tool is now over 150.  However, the in-plane shear performance of these horizontal diaphragms is limited to that for houses as opposed to the non-residential projects where higher shear performances are required.

As part of Canada Wood Japan Market Access projects of this year, we have been working on developing horizontal diaphragms for non-residential structures with SPF dimension lumber.  With 5 specifications, in-plane shear tests have been conducted at the Centre for Better Living laboratory in Tsukuba City.  Starting on November 25th, testing is going on relatively smoothly, showing significant performance differences from one specification to another.  The testing apparatus in the photographs here look like a vertical set-up, but it actually is the equipment arrangements for testing the horizontal in-plane shear capacity. This test program will similarly result in data and technical tools that will enable specifying Canadian dimension lumber products in larger scale post and beam non-residential structures.