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Shear Strengthening of RC Beams Using Prestressed Near-Surface Mounted Bars Reducing the Probability of Construction
Sabry Fayed1, Mohamed Ghalla1, Jong Wan Hu2,3
1Civil Engineering Department, Faculty of Engineering, Kafrelsheikh University, Kafr El-Sheikh 33516, Egypt.
Materials (Basel, Switzerland)
|December 17, 2024
Summary
This study enhances the shear capacity of reinforced concrete (RC) beams using combined prestressing and near-surface mounted (NSM) rod techniques. These methods significantly improve structural safety and building sustainability by mitigating failure risks.
Area of Science:
- Civil Engineering
- Structural Engineering
- Materials Science
Background:
- Shear failure in reinforced concrete (RC) beams poses a significant safety risk in buildings.
- Existing strengthening methods for RC beams have limitations in addressing shear-critical failures.
- Enhancing the safety and sustainability of buildings requires effective mitigation strategies for RC beam failure.
Purpose of the Study:
- To investigate the effectiveness of combined prestressing and near-surface mounted (NSM) rod techniques for strengthening shear-critical RC beams.
- To experimentally and numerically analyze the structural behavior of strengthened RC beams.
- To reduce the probability of failure risk in RC beams, thereby enhancing building safety and sustainability.
Main Methods:
- Ten RC beams were tested, with nine strengthened using various techniques: internal prestressing (IP), external prestressing NSM (PNSM), and internal embedment (IE) with or without prestressing.
- Extra shear reinforcement ratios (μs) ranged from 0.87% to 1.60%.
- Structural performance was evaluated based on cracking load, ultimate load, load-deflection response, ultimate deflection, and stiffness.
Main Results:
- PNSM rods (μs = 1.45%) increased shear capacity by 57.8%, while IP rods (μs = 1.6%) increased it by 70.4%.
- IE rods (μs = 1.02%) resulted in a 23.2% increase in shear capacity.
- Internal prestressing demonstrated superior performance compared to external prestressing.
- Stiffness increased by 20% to 84.4% with the addition of internal prestressing rods.
Conclusions:
- Combining prestressing and NSM rod techniques is an effective method for strengthening shear-critical RC beams.
- The location of prestressing significantly impacts shear capacity, with internal prestressing being more effective.
- A novel formula is proposed for calculating the shear capacity of RC beams strengthened with various methods, contributing to improved structural design and safety.
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