The Flexural Capacity Of Reinforced Concrete Short Beams Strengthened With Carbon Fiber Reinforced Polymer Sheets(CFRP)

With the development of the society and economy, our country has entered the second stage of building development, that is the construction and retrofitting stage, a large number of the buildings in-service need maintenance and reinforcement. As a new material for reinforcing the concrete structure, carbon fiber reinforced polymer sheet (CFRP) has been favored by scholars and engineers from various countries because of its superior high-strength, high efficiency, corrosion resistance and fatigue properties. At present, the research for concrete structure reinforced by CFRP mainly focuses on the members such as beams, slabs, columns, shear walls and beam-column joints etc, the research for short beams reinforced by CFRP is few. Therefore, this paper carried out the experimental research about the flexural behavior of the concrete short beams reinforced by CFRP, the main contents are as follows:(1) The experimental parameters are concrete strength and reinforcement ratio, the flexural performance tests of five reinforced concrete short beams strengthened with CFRP and a short beam un-strengthened have been completed. The results showed that CFRP has a little effect on the cracking load of reinforced concrete short beams, but greatly increases its ultimate load and stiffness, the crack development of concrete short beams reinforced by CFRP is different; the effect of the reinforced concrete short beams strengthened with CFRP relates to the concrete strength, the short beams with high strength concrete is better than the low; compared to the short beams with high reinforcement ratio, the effect of short beams with low reinforcement ratio is more obvious; the reason for CFRP improving the bearing capacity of the reinforced short beams is mainly due to CFRP improving the strength utilization of each material in short-beam.(2) The different failure modes of the short beams strengthened with CFRP are defined based on plane assumption. Combined with the calculation method of deep flexural members in the "Design of Concrete Structures" (GB50010-2010), through the introduction of the arm correction factor related to the span of the short beam and the cross-sectional analysis, the flexural calculation formula of the reinforced concrete short beams strengthened with CFRP under different damage states is derived.