Experimental investigation and evaluation of metal-plate-connected laminated bamboo lumber joints

Abstract

This study focused on the mechanical performance of toothed metal-plate connected (MPC) laminated bamboo lumber (LBL) joints aiming to apply this metal-plate connection to the design and manufacturing of engineered bamboo trusses, due to the merits of the cost-effective and easy installation. A total of 212 MPC LBL and SPF (spruce-pine-fir) joints connected by the domestic toothed metal plates were tested in accordance with Chinese standards. Particular emphasis was placed on the load-slip behavior of metal plate teeth embedded in LBL with varied load direction related to the major axis of the toothed metal plate. Design values of the tensile and shear strength of the net section cross metal plate connector, and the anchorage and anti-slip strengths of the metal plate teeth embedded in LBL were presented in accordance with the existing timber design specification. Test results reveal that the metal plate orientation has a significant effect on the mechanical performance of MPC LBL joints. A new angular equation, expressed as the metal plate orientation, was proposed for evaluating the anchorage and anti-slip strengths of MPC LBL joints, which shows an obvious reduction in predicting error compared with the existing method. Design strength values of LBL joints are higher than those of the corresponding SPF joints, mainly due to the relatively smaller dispersion of LBL compared with SPF, indicating that the MPC LBL is expected to replace MPC timber in truss systems. The results of the comparison of MPC LBL and glubam (glued laminated bamboo) joints also suggest that arranging transverse bamboo strips is an available option for improving the anchoring mechanical performance of MPC LBL joints.