Analyzing the effects of size and density on the ultimate compressive strength of structural laminated bamboo parallel to the grain

Considering the influence of natural flaws of raw materials and procedures, the size effect is an inherent characteristic that is critical when applying most construction materials. This study focuses primarily on the compressive properties of laminated bamboo, which has become increasingly popular in construction due to its durability and strength. Two specimen sizes (25 × 25 × 100 mm and 50 × 50 × 200 mm) and three densities (0.60, 0.67, and 0.69 g/cm3) were evaluated under uniaxial compression. As a result of this study, the size effect is examined in terms of failure mode, mechanical property, data distribution, and description model, as well as introducing the size effect model with density in an innovative manner. To investigate the effect of specimen size on compressive strength along the grain direction, data analyses were performed. These analyses included failure mechanism analysis, distribution testing, and descriptive model development. According to the results, the compressive strength decreases with increasing dimensions, averaging 62.29 MPa-56.93 MPa, with a decrease rate of 8.60 %, although the failure modes are seldom different. In accordance with the increase in density, the rate of strength reduction also increases, and shows an approximate linear relationship with density. With the change in size, the distribution of the data changes, resulting in a reduction of up to 13.34 % in the standard value. The weakness-link model is better suited for describing data than fracture energy models and fractal theory models, based on which reduction ratios are predicted. By adding density to the size effect model, a more accurate prediction model can be derived between size, density, and compressive strength. As a result of these investigations, we will gain a better understanding of the gap between small clear specimens and large members, as well as those key influences necessary to optimize the use of laminated bamboo in structural applications.