Creep and duration of load characteristics of cross laminated timber (CLT) were evaluated from the test results of creep and duration of tests. Japanese Ceder (Cryptomeria japonica) was chosen for the specie for the laminations of the test specimens and API was chosen for the adhesive. The results are summarized as follows: (1) The creep factor [i.e. (Initial deflection + Creep deflection) / Initial deflection] for CLT was evaluated to be 2.0 and was almost equivalent to the creep factor commonly known for solid lumber. (2) The duration of load factor [i.e. Strength for 50 years duration of load / Strength for 10 minutes duration of load] of CLT was evaluated to be 0.66 and was almost equivalent to the duration of load factor measured for solid lumbers.
Rocking of narrow wall panels/columns causes embedding forces on the floor panels during earthquakes. In plain/out of plain compression tests and out of plain embedding tests of CLT panels were conducted. Compression and embedding strengths of in plain/out of plain strengths of Sugi CLT panels were obtained. These strengths of CLT panels with /without edge-glues were compared. Out of plain embedding strength loaded at the corner of CLT panels was fairly less than the normal embedding strength, and it was around the middle of the normal embedding and compression strengths.
Seismic design is required to CLT buildings in Japan. Embedding performance of joints is significant to maintain ductility of timber structures during earthquakes. CLT wall panels are installed on the CLT floor panels, and narrow wall panels and columns make rocking on the floor panels during earthquakes. Both edges of the wall panels apply embedding forces on the floor panels. Tension behaviour of the joints between wall and floor panels is dominated by those of connecters, etc. Compression behaviour of the joints depends on the embedding behaviour of in plain/out of plain CLT panels of walls and floors. In plain/out of plain compressions, out of plain embedding and rotational embedding performance of CLT panes are required to be clarified. In plain/out of plain compression tests and out of plain embedding tests of CLT panels are conducted. Effects of edge-glue of CLT panels are also analysed.
An investigation was carried out on CLT panels made from Sitka spruce in order to establish the effect of the thickness of CLT panels on the bending stiffness and strength and the rolling shear. Bending and shear tests on 3-layer and 5-layer panels were performed with loading in the out-of-plane and in-plane directions. ‘Global’ stiffness measurements were found to correlate well with theoretical values. Based on the results, there was a general tendency that both the bending strength and rolling shear decreased with panel thickness. Mean values for rolling shear ranged from 1.0 N/mm2 to 2.0 N/mm2.