Evaluation of flexural strengthening methods for beams with simulated deterioration using spike-anchored FRP externally bonded sheets and near-surface-mounted strips

Abstract

• 20 beams were tested to evaluate FRP flexural strengthening techniques. • Specimens were detailed to mimic the common deterioration of bridge beams. • The effect of FRP spike anchor arrangements were evaluated. • Results show that more FRP spike anchors may not translate to superior performance. • Unsymmetrical steel and NSM reinforcement layouts were considered. In consideration of past research on both externally bonded and near-surface-mounted (NSM) fiber-reinforced polymer (FRP) reinforcement for the strengthening of deteriorated reinforced concrete elements, additional work is needed to investigate the application of FRP for flexural strengthening in specific scenarios and for specific member types. Furthermore, the need exists for guidance regarding reliable anchorage of externally bonded sheets for flexural strengthening. An experimental investigation was conducted on 20 reinforced concrete beam specimens with details and simulated deterioration patterns representative of the beams of in-service adjacent box beam bridges. Special focus was placed on the effective arrangement of FRP spike anchors for externally bonded FRP, unsymmetrical deterioration of steel reinforcement, and the eccentric placement of NSM strips. The results show that spike anchors located only at the ends of the externally bonded FRP sheets provided superior performance compared to anchors placed at multiple locations along the sheets. Moreover, the eccentricity of reinforcement did not play a significant role in the effectiveness of the strengthening systems. The test results also highlight the importance of bond on the performance of members strengthened with NSM reinforcement. Overall, the findings extend beyond adjacent box beam bridges and have a wide applicability to other flexural members.