Experimental Study on Axial Compression Behavior on Circular Timber Columns Strengthened with CFRP Strips and Near-Surface Mounted Steel Bars

Abstract

To investigate the working mechanism and reinforcement effectiveness of the ancient timber columns strengthened with carbon fiber reinforced polymer (CFRP) strips and near-surface mounted steel bars, in this paper, 42 timber columns have been tested under axial compression, which considered the arrangement modes of CFRP strips, number of near-surface mounted steel bars, and different strengthening ways as the main influencing factors. Based on the test results, failure modes of specimens and materials were analyzed, compressive bearing capacity and ultimate deformation of each specimen were obtained, and load-displacement curves of timber columns were diagramed. Moreover, the load-strain curves of specimens were obtained through the data collected using an extensometer, and the deformation compatibility performance of three different materials was evaluated according to the strain comparison. The test results indicate that the wrapped CFRP strips way and near-surface mounted method can work together to mutually boost the reinforcement effectiveness. The proposed composite reinforcement method can significantly improve the bearing capacity and deformation performance of timber columns. Moreover, the increase in the number of CFRP strips and steel bars generates a marked enhancement in timber columns’ compression performance. The load-strain curves of timber, steel bars, and CFRP strips are in good agreement, and the percentage differences of three different materials’ strains are almost lower than 20%, illustrating that three types of materials have acceptable deformation compatibility performance.