Advanced in Strengthening Prestressed Concrete Beams: A Comprehensive Review of Modern Techniques

Prestressed concrete (PSC) beams are widely used in construction worldwide, especially for bridges due to their high strength, durability, and efficient load-carrying capacity. However, over time, these structures face deterioration from various factors, such as material aging, fatigue, environmental factors, and increased service loads, requiring strengthening methods. Many studies have investigated various materials and schemes for improving the flexural and shear capacities of (PSC) beams. This review aims to explain external strengthening techniques for (PSC) beams, including steel plate bonding, external post-tensioning method, Fiber-Reinforced Polymers (FRP), and shape memory alloys (SMAs). A review was conducted to investigate the effects of various strengthening methods on the performance of (PSC) beams, focusing on crack propagation modes and specimen failure related to flexural and shear improvement techniques. Flexural strengthening enhances bending capacity and serviceability by reducing deflections and improving load resistance. In contrast, shear strengthening techniques aim to prevent diagonal shear cracks and brittle failures near support zones. A comparative analysis highlights each method's advantages, limitations, and applicable contexts, highlighting their impact on structural performance and longevity. The discussion also includes these techniques' knowledge gaps, challenges, and constraints while proposing future research directions to improve their effectiveness. This review study offers significant insights for engineers and researchers focused on enhancing the performance and durability of (PSC) beams by recent strengthening techniques.