The Study of The Behavior and Failure Modes of Reinforced Concrete Beams Strengthened Enhanced by External Steel Plates

Abstract

This study investigates the behavior of reinforced concrete beams subjected to strengthening techniques. Steel plates were affixed to the beams using epoxy bonding supplemented with bolts for attachment, and the beams were tested under a four- point bending configuration. The reinforced concrete beams used in this investigation had dimensions of 15 cm in width, 20 cm in depth, and a length of 240 cm, incorporating both tensile and compressive reinforcement. The study comprised five samples: one control beam and four strengthened beams. Strengthening actions were implemented in two configurations: with steel plates attached to the tension surface and with a combination of a steel plate at the bottom of the beam and a U-shaped steel plate band.

The results encompassed the load-deflection relationship, failure modes, and cracking behavior of the tested beams. The findings suggest that the control beam is susceptible to failure primarily due to tension-induced bending. Strengthened beams, reinforced by steel plates on the tension surface, exhibited increased loading capacities of 40% to 50%, compared to the control beam, along with characteristics of shear failure. In contrast, beams reinforced with a steel plate at the bottom and a U-shaped steel plate band displayed even greater enhancements in loading capacity, with improvements of 70% to 80%, respectively, over the control beam. However, it should be noted that incomplete detachment of steel plates may lead to failure and compromise composite integrity.