Evaluation on the ultimate bearing capacity for laminated bamboo lumber columns under eccentric compression

Engineered bamboo is gaining widespread interests from researchers to exploit its excellent functional characteristics in practical engineering applications. Laminated bamboo lumber (LBL) is one of many engineered products that are currently available with the potential to be used in the construction sector. The size and shape of LBL can be easily controlled to suit design requirements making it competitive with other commonly used building materials. This paper presents a recent investigation on the behaviour of LBL columns under eccentric compression loading, and proposes analytical formulations for predicting the ultimate resistance of columns with special emphasis given on observed failure mode types. Closer inspection revealed three characteristic failure modes, denoted as Mode I, II and III hereafter, for LBL columns under eccentric compression. In Mode I, failure was initiated from glue or bracket but all bamboo fibers remained elastic; in Mode II the outer most compression fiber reached elastic-plastic stage and eventually triggered failure; and in Mode III outer most part of compression fiber achieved plastic capacity prior to failure. Detailed analytical models have been developed and presented herein for all observed failure modes' and the performance of the proposed design equations are compared using test evidences reported by the authors. The proposed equations produced very good agreement with the experimentally obtained results, and may be adopted in future design codes for engineered bamboo.