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Received Aug 3, 2017; Accepted Apr 2, 2018
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1. Introduction
Normally, RC beams are designed to have a higher shear capacity than flexural capacity, so shear failure can be avoided as it is brittle and sudden in nature. However, multiple causes such as severe corrosion of the steel stirrups due to deterioration or change in loading can lead to lower shear capacity. In addition, flexural strengthening of RC members may cause the shear capacity to be insufficient which is highly unrecommended and shear strengthening would become necessary. In the recent years, upgrading the structural performance of RC structures by strengthening with externally bonded plates has gained an increasing popularity using materials such as steel plates, aluminum alloy plates [1, 2], FRP composites [3–6], and natural fiber plates. On the other hand, strengthening using steel plates has its advantages, such as cheap and reliable, ease of installing, high tensile modulus, and excellent compatibility with concrete [7]. In addition, the advancement of new materials and technologies has led researchers to investigate various designs and materials to increase the strength of shear critical RC beams [8–14]. Shear strengthening of rectangular RC beams with steel plates can be applied using three different approaches: full wrapping, U-wrapping, and side strips. Side strips are the least effective as it easily debonds from the concrete surface, while full wrapping provides the highest effectiveness followed by U-wrapping. However, side-bonded strips are the most practical to apply where it does not need access to the top or the bottom of the beam. Premature debonding of EB plates is the main weakness of the system where it is caused by concrete cracks leading to the separation of the adhesive from concrete surface at ends of strengthening plate. Many studies have been done on the side-bonded method over the past two decades [5–7, 15–19]. Numerous materials, arrangements, and anchors have been investigated to increase the shear capacity of the RC member as well as delay the premature debonding failure in externally bonded (EB) members [10, 20–30, 31].
Various anchor designs were proposed to overcome the issue...