Experimental and theoretical investigation into flexural performance of thin-walled steel-laminated bamboo lumber truss beam

Abstract

This study presents a novel truss beam called thin-walled steel-laminated bamboo lumber truss beam (SBTB). The SBTB is composed of cold-formed thin-walled steel chords and laminated bamboo lumber web members. A total of 24 SBTBs were divided into eight groups, each group containing 3 specimens, to investigate various parameters, including bamboo web member thickness and laminated direction, number of self-drilling screws, shear span ratio, and truss beam height and width. The flexural performance of SBTBs was evaluated through a four-point bending test, analyzing the failure mode, deflection, bearing capacity, and bending stiffness. The impact of different parameters on the flexural performance was thoroughly examined and discussed. In addition, a theoretical model and simplified prediction approach for the bending stiffness of SBTBs were developed. The results identified five failure modes during the flexural tests and demonstrated the linear elastic and nonlinear stages of the SBTB working process. Increasing the width and height of the beam, the number of self-drilling screws, and adopting plain pressed laminated bamboo lumber web members significantly improved the bending resistance of the composite truss beam. Notably, the theoretical model accurately predicted the stiffness of SBTBs, with a maximum discrepancy of less than 12.3 % between experimental and theoretical results.