The shear moduli evaluation of cross laminated timber using torsion test

Cross laminated timber (CLT) has gained popularity in Europe and North America due to its versatile applications as structural walls, girders and slabs. Its economic competitiveness, high carbon absorption and sustainability make it as an excellent building candidate. The CLT panel is made of alternately orthogonal glued layers. When subjected to out-of-plane loading, the panel is prone to fail due to its weakest rolling shear capacity. Therefore, it is necessary to characterize its rolling shear capacity before a full adoption of this material. Coniferous planks made of yellow pine, and Taiwan planted Japan cedar are cut along their tangential, radial and cross sectional planes to produce the testing pieces. Structural size timber bars of yellow pine and Japan cedar with lengths of 30 cm long, respectively, are mounted on a torsion machine to measure their shear moduli. Strain gages, extensometers and inclinometers are mounted on the surface of the bar to record the shear strains and twisting angle during torsion test. A novel design of mounted strain gages and extensometers allows the simultaneous measurement of shear moduli GLR and GLT using one specimen which can reduce the amount of test coupons and material property variations. The setup of detachable clip on extensometers can further save the adhering time of strain gages.