Ultimate strength of bamboo scrimber-concrete composite beams with UHPC and ECC: Experimental investigation, finite element simulation and prediction model

Timber-concrete composite (TCC) beams are commonly used in modern construction. By combining bamboo scrimber with high-performance concretes such as engineered cementitious composite (ECC) and ultra-high-performance concrete (UHPC), bamboo scrimber-concrete (BC) beams can improve structural performance and support environmental sustainability. This study conducted static tests on BC beams incorporating UHPC and ECC, with three different shear connectors designed for evaluation. The analysis focused on the failure modes, mechanical behaviors, and strain distribution of the beams. The results demonstrate that UHPC significantly enhances ultimate strength, while ECC improves ductility compared to BC beams with ordinary concrete. Additionally, this study revealed the influence mechanism of concrete type and shear connectors on the structural behavior of BC beams. Finite element models were further developed to explore the failure mechanisms of BC beams with various concrete materials. These validated models provided insights into stress variations in the concrete, shear connectors, and bamboo scrimber, offering a clearer understanding of the interfacial load transfer mechanism. The height of the compressive zone in BC beams was also quantified. Based on these findings, a prediction model for the ultimate strength of BC beams was developed, taking into account composite action and fiber bridging. The model's accuracy was validated, making it a reliable reference for practical engineering applications.