Abstract
Strengthening with externally bonded CFRP reinforcement is widely used in structural reinforcement and attractive to stakeholders and engineers because of ease and speed of construction, corrosion resistance, lightweight, high strength, and versatility stiffness which can be oriented according to the need. Numerous research studies were carried out to explore RC beams’ flexural and shear performance when subjected to dynamic impact loading. The results were auspicious in using such a technique of strengthening. Regular square section reinforced concrete frame members strengthened by CFRP material is taken as the research object. However, little attention to the impact behavior of CFRP-shear-strengthened square reinforced concrete (RC) specimens has been paid. The dynamic response of CFRP to reinforced concrete members under unequal cross-impact is discussed. This paper investigates the effectiveness of CFRP strengthening on the square RC specimen in preventing shear failure and evaluation of the flexural performance of the strengthened specimen under the impact load. The drop hammer impact test is firstly conducted on RC specimens with and without CFRP strengthening. The results show that using CFRP to strengthen the RC specimen in shear is very effective at preventing shear failure and leading the specimen’s response to flexural domination. This result is also the motivation for developing a numerical model supported by experimental tests to study the flexural performance of strengthened RC specimens. It is found that the strengthened specimen is prone to exhibit pure bending deformation under the impact load in terms of dynamic amplification factor (DAF) for section moment. Then, an extensive parameter study is carried out to evaluate further the influence of impact velocity, reinforcement ratio, and concrete strength on the flexural performance of the strengthened specimen and CFRP layers. Such a holistic study may provide preliminary research regarding the use of CFRP to strengthen RC specimens in shear under impact loads and will enhance the current state of knowledge in this area; also, the optimal value of the CFRP reinforcement layer was proposed.
Highlights
Due to the demand in the engineering construction field, Fiber-reinforced polymer (FRP) was introduced in the 1980s to enhance the tensile and compressive strength of materials employed in this field, which promotes more efficient, safe, stable, environmentally friendly, and strong structures
Ultimate strength for longitudinal and stirrups reinforcement was 320 MPa and 520 MPa, respectively, and the tensile test of steel bars, as shown in Figure 3(a). e compressive test was performed on 150 mm ∗ 150 mm ∗ 150 mm concrete cubes, as shown in Figure 3(b). e average measured the strength of concrete cubes at 28 days was 43.5 MPa. e unidirectional carbon fiber reinforced polymer (CFRP) material used in this study was supplied by Torayca Inc. [10]. e CFRP sheet was commercially known as UT70-30G [11]. e density and thickness of CFRP sheets were provided by the supplier
CFRP strengthening can lead the reinforced concrete (RC) specimens to be governed by flexural responses under the impact. is failure mode usually is more acceptable than shear failure mode due to its greater ductility with adequate energy dissipation capacity. us, based on the numerical models, this section further investigates the development of bending moments of the tested specimens by using experimental results and finite element (FE) analysis
Summary
Due to the demand in the engineering construction field, FRP was introduced in the 1980s to enhance the tensile and compressive strength of materials employed in this field, which promotes more efficient, safe, stable, environmentally friendly, and strong structures. Fiber composite materials such as carbon fibers have been utilized in many applications and transformed to this construction field throughout the life cycles of the RC structures considering the late 1980s [1].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
