For a cross-laminated timber (CLT) manufactured using Sugi, a digging test was performed by changing the number of layers, the laminar configuration, the direction of the outer layer laminar with respect to the direction of the pressure plate, and the arrangement of the test piece with respect to the load direction, and each combination was performed. In addition to clarifying the sunk strength performance of CLT, a method for easily evaluating the sunk strength performance was examined. As a result of the sinking test, it was found that the parameters that determine the sinking strength performance are the direction of the outer layer laminar and the arrangement of the test piece, and the number of layers and the laminar configuration do not contribute much to the sinking strength performance. When the proportional limit stress of CLT was estimated using the proportional limit stress of each laminar, the estimated value and the measured value were in relatively good agreement.
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.
Cross-laminated timber (CLT) has recently emerged as a new wood product that utilizes a large quantity of domestic lumber. This study aims to analyze the effects of width and lay-ups on the tensile strength of CLT. To this end, the elastic modulus of sugi CLT with different lay-ups was measured by dynamic and static methods. Moreover, tensile tests were conducted for different widths and lay-ups of CLT. Results indicate that the apparent bending Young’s modulus, as calculated using the dynamic method, is directly proportional to the measured Young’s modulus in static method for each lay-up. Furthermore, there was no significant effect of width on the tensile strength in the range of 150, 300, and 600 mm. However, the variations in lay-ups affected the tensile strength as follows: CLT with larger ratio of the major strength direction lamina along the cross-section and with higher grade of lamina in the major strength direction showed higher tensile strength. The estimated tensile strength of CLT, as calculated using the Young’s modulus of the lamina of each layer, and the tensile strength of lamina as simple substance was found to be in good agreement with the measured tensile strength of CLT.
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.
The Japanese Building Code provides formulas to calculate the buckling strength for structural lumber and structural wooden engineered products such as glulam and LVL. The adaptability of these formulas against cross laminated timbers is discuss in this paper. To determining the buckling strength properties for cross laminated timbers a series of buckling test were operated for full-size cross laminated timber of certain structural grades. The buckling loads obtained though these tests were compared to those derived from the formulas given in the Japanese Building Code. The measured buckling loads and the calculated buckling loads were almost equivalent. The result indicated that in general the formulas given in the Japanese Building Code can well evaluate the buckling strength of cross laminated timbers.
The in-plane shear specimens of full scale CLT panels are tested. From the test results, about the failure behaviour, if there is finger joint near the shear plane, cracks are tended to progress along the joint was confirmed. About the maximum shear unit stress was about 3N/mm2 , and shear stiffness was about 600GPa calculated as the total cross section effective.
CLT is composed of longitudinal layers and cross layers. When the CLT is used as shear wall, it is important to understand the in-plane shear performance in order to control the structural performance of wall and joints and the collapse mechanism. Therefore, the in-plane shear specimens of full scale CLT panels are tested.