Experimental and numerical investigation of concentric axial loading on bar-reinforced composite timber columns at a large scale

This study presents an innovative investigation into the performance of a composite column comprising timber and steel. The research involved conducting tests on 22 large-scale columns, each with a length of 2 m. The columns were constructed using steel bars in combination with three types of timber: (i) Pinus radiata (Radiata Pine) of MGP10 grade, (ii) Pseudotsuga menziesii (Douglas fir) of F7 grade, and (iii) engineered timber known as LVL (Laminated Veneer Lumber). The bonding of these materials was achieved through the use of mechanical fasteners and an epoxy adhesive. To evaluate the strain characteristics of the specimens, a non-contact technique called Digital Image Correlation (DIC) was employed. Additionally, strain gauges were utilised to accurately determine the initiation and progression of cracks. This study focuses on the assessment and discussion of essential parameters including peak load, ductility, axial stiffness, and strength-to-weight ratio. The experimental findings, complemented by analytical and Finite Element Analysis (FEA), revealed a substantial increase in load-carrying capacity (up to 106.6%) and stiffness when compared to unreinforced timber columns. This enhancement is attributed to the incorporation of steel bars within the composite column. Moreover, the analytical and FEA approaches demonstrated a high level of consistency (± 5%) when compared to the experimental data, further validating the results. This study provides valuable insights into the performance of composite columns consisting of timber and steel. The research findings highlight the significant improvements in load-carrying capacity and stiffness achieved through the use of steel reinforcement. The analytical and FEA analyses also demonstrate the accuracy and reliability of the proposed methods, thus contributing to the understanding and advancement of composite column design.