The strengthening or rehabilitation of civil engineering infrastructures has been a vital issue for the past few decades due to increased loading requirements, usage changes, and deterioration of existing infrastructures.

Several well-known strengthening techniques such as a fiber-reinforced polymer (FRP) sheet and external steel plate have been proposed and extensively studied for decades. Adhesively attached FRP sheet or steel plates to the bottom soffit of RC beams or girders was proposed three decades ago, which improved the flexural capacity and stiffness of beams or girders. However, premature debonding of steel or FRP plates is usually observed and leads to sudden failure of structural members. Therefore, it is essential to develop new strengthening systems or composite materials for increasing the structural capacity as well as the improved failure modes of the members.

This Special Issue aims to collate original research and review articles describing current trends and recent advances in this field.

Potential topics include but are not limited to the following:

• Strengthening of structures
• Rehabilitation or retrofitting of existing structures
• Fiber-reinforced composite materials
• Innovative strengthening techniques or systems
• Sustainable mortar for replacement of conventional adhesives
• Ultra-high-performance fiber reinforced concrete (UHPFRC) laminates
• UHPFRC laminates for strengthening of infrastructures
• Health monitoring or assessment of existing RC bridges
• Pre-stressing strengthening system for improving capacities
• Steel structures strengthened with FRP