Design Embedment Strength of Plybamboo Panels Used for GluBam

Abstract

The embedment behavior of plybamboo panels under dowel-type connections used for glued, laminated bamboo (GluBam) structures, was experimentally studied, following the half-hole loading method suggested by ASTM standards, further improved to deal with small-diameter connections. Embedment stress curves were obtained under six different loading directions, with three types of metal connectors, from 2-mm-diameter nails to 14-mm-diameter bolts. The corresponding compression tests in the same six directions were also performed as reference. Based on the original test data, embedment strength values were calculated as defined by ASTM standards. The maximum embedment strength observed from the tests was about 80 MPa when the nail was placed orthogonal to layers and orthogonal to fibers, and the minimum embedment strength was about 20 MPa when the nail was placed parallel to layers and parallel to fibers. Moreover, the compression curves were always below the corresponding embedment stress curves. Semiempirical regression-based capacity equations for the embedment strengths under different loading directions were given as a function of the plybamboo density and the connectors’ diameters. The 5% characteristic values and the design values of the embedment strength were estimated from test data, based on the design-by-testing method suggested in European standards. Results from this research can be used to predict the ultimate strength of GluBam connections, as well as to obtain reliable design values for engineering applications.