Flexural fatigue strength of RC bridge girders strengthened by PHSW-PM

A novel method for enhancing the flexural fatigue strength of reinforced concrete (RC) bridge girders is presented. This method adopts externally attached prestressed high-strength steel wires covered by polymer mortar, referred to as PHSW-PM. To evaluate the effectiveness and applicability of this technique, monotonic and fatigue tests were conducted on RC beam specimens subjected to repeated load cycles within service load ranges. The investigation focused on four main parameters: the loading condition, the prestressing level of the high-strength steel wires, the anchorage condition, and the bond properties between the polymer mortar and the concrete surface. The RC specimens strengthened with PHSW-PM demonstrated exceptional performance under fatigue loading, withstanding over two million repeated load cycles without failure. The test results revealed that a higher level of prestressing force in the steel wires significantly enhances the crack resistance of the strengthened beams. Additionally, the bond interface condition between the polymer mortar layer and the concrete surface, along with the type of anchorage, were identified as critical factors influencing the flexural fatigue capacity and ductility of the strengthened beams. Based on the experimental results, an empirical design formula has been derived to evaluate the flexural fatigue capacity of beams strengthened using the PHSW-PM methodology. This study provides valuable insights into the potential of PHSW-PM as an effective technique for improving the structural performance of RC bridge girders under cyclic loading conditions. • Present a novel method for enhancing flexural fatigue strength of reinforced concrete bridge girders. • Conduct monotonic and fatigue tests on large-scale RC beams subjected to repeated load cycles. • Derive an empirical design formula to evaluate the flexural fatigue capacity of strengthened beams.