A Comparison of Shear Strength of Box-section Beam Made of Sliced-laminated Dendrocalamus Asper Under Torsion and Transversal Load

This study was purposed to compare shear strength of box-section beams based on torsion test, and shear strength based on four point bending test. Eight beams for torsion test and nine beams for four point bending test of laminated Dendrocalamus Asper (Petung bamboo) bonded with 268 g/m2 of urea formaldehyde were made for this research. The beams were engineered using cool-pressed by 2,0 MPa for 4 hours. The sizes of square-section of the beams are 80 mm, 120 mm, and 160 mm with 15 mm, 20 mm, and 25 mm thick. Based on the torsion test, the research showed that the maximum shear stress was in the range of 4.39 MPa to 10.13 MPa with an average of 6.50 MPa. Shear modulus of the beam was in the range of 690.68 MPa to 1,072.28 MPa with the average of 902.10 MPa. Using four point bending test, the research results showed that the maximum shear stress was in the range of 2.86 MPa to 4.85 MPa with the average of 4.06 MPa. Modulus of elasticity of the beam was in the range of 11,363.37 MPa to 15,739.23 MPa with the average of 13,502.30 MPa. The maximum shear stress based on the torsion test was significantly differed to the maximum shear stress based on the four point bending test.