Flexural Strengthening of Large-Scale RC Beams with Nonprestressed and Prestressed CFRP Using Different Anchorages

Area of Science:

• Civil Engineering
• Materials Science
• Structural Engineering

Background:

• Externally bonded carbon-fiber-reinforced polymer (CFRP) is a common technique for strengthening concrete structures.
• Various anchorage devices, CFRP types, and prestressing strategies exist, but direct efficacy comparisons are limited.

Purpose of the Study:

• To investigate the flexural strengthening efficacy of different anchorage methods, CFRP types, and prestressing techniques on reinforced concrete (RC) beams.
• To provide a direct comparison of various CFRP strengthening approaches.

Main Methods:

• Seven large-scale RC beams were tested under controlled laboratory conditions.
• The study systematically varied anchorage methods (U-wraps vs. wedge-clamp anchors), CFRP types (plate vs. sheet), and prestressing (prestressed vs. nonprestressed).
• Flexural behavior was evaluated based on cracking, yielding, and ultimate loads.

Main Results:

• Enhanced anchorage from U-wraps to wedge-clamp anchors increased ultimate load by 38.3% with minor effects on cracking and yielding loads.
• CFRP plates and sheets showed similar strengthening efficacy for equivalent amounts.
• Prestressed CFRP plates significantly outperformed nonprestressed plates, increasing cracking, yielding, and ultimate loads by 57.1%, 22.9%, and 5.9%, respectively.
• Both adhesive-friction and wedge-clamp anchor prestressing systems proved effective and comparable for prestressed CFRP plates.

Conclusions:

• Wedge-clamp anchors offer superior ultimate load enhancement compared to U-wraps.
• Prestressing is a critical factor for maximizing the flexural strengthening benefits of CFRP plates.
• Both tested prestressing systems are effective for enhancing RC beams with prestressed CFRP plates.