Timber Beams Strengthened with Fiber-Reinforced Polymer Sheets or Near-Surface-Mounted Reinforcement: Comprehensive Database and Flexural Strength Prediction

This is the authors' abstract. We don't add key points for this paper.

As the use of timber and mass timber rises in popularity, so too will the need to develop strengthening solutions to improve their structural load-carrying capacity over time. Several solutions have been proposed and studied in the literature, including externally bonded fiber-reinforced polymer (FRP) sheets and near-surface-mounted (NSM) reinforcement. Despite work in the literature regarding these areas, there is an ongoing need to develop an experimental database of tests to compare existing analytical methods proposed to predict their flexural strength. Furthermore, there is a need to collect high-resolution strain data during experimental testing to confirm common modeling assumptions. This study addresses these concerns by establishing a comprehensive data of experiments conducted on timber beams strengthened with externally bonded FRP sheets, NSM reinforcement, or both. The database includes over 80 individual beam tests with varying beam sizes, timber materials (e.g., solid timber, dimensional lumber, glulam), and reinforcing materials (e.g., FRP or steel). Results in the database are compared with a common approach used in the literature to evaluate the moment resistance of strengthened timber beams, and a common set of modeling parameters is proposed. Furthermore, additional tests are conducted on beams instrumented with distributed fiber optic sensors to confirm common modeling assumptions. In comparison with the experimental database, the average test-to-predicted ratio for beams strengthened with externally bonded FRP sheets was 0.99 (COV = 0.12), while for beams strengthened with NSM reinforcement, the average test-to-predicted ratio was 0.94 (COV = 0.08). Finally, limitations of the method are also discussed.