Experimental investigation of impact behavior of reinforced concrete beam strengthened with CFRP

Concrete widely used as structural building materials in civil engineering applications. One of the major external forces effects on the concrete structures is the impact forces throughout its economical life. The determination of the magnitude, the excitation time and the deformations due to impact loading is a complicated and rarely known subject. There are no certain solid regulations or standard test setups for determining the impact strength and behavior of concrete. Although there are some limited studies about impact behavior of concrete. The number of the studies which is including the drop weight impact tests on concrete as a impact method recently increased. In addition to that, the studies on the strengthening of concrete structures against impact loading are few in the literature. In this study, the high and low strength RC beam specimens are strengthened with CFRP and tested under impact loading experimentally. The behavioral difference between the normal and strengthened specimens under impact loading were observed and reported. Total 10 rectangular cross sectioned RC beams with coverage and high strength concrete specimens were tested. The specimens were strengthened similarly with CFRP strips and tested under the drop weight impact test apparatus with constant weight hammer but different drop heights. The hammer which has a constant weight and geometry was dropped from 750, 700, 650, 600 and 550 mm height. The concrete compression strength and the drop heights are the major investigation parameters of the experimental study. The CFRP strip width and its length were kept constant. Drop velocity, displacement and energy dissipation capacities of the specimens were calculated through the acceleration instrumentations on the specimens. The variations of the strength, the number of the drops, accelerations, and failure mechanisms were investigated and the results taken from normal and high compression strength concrete specimens were compared. In addition, computer simulations of the same experimental impact test are performed by using Abaqus finite element software. The results of finite element analysis and experimental studies were compared, and finite element model was compared with that of the experimental results. As a result of finite element analysis a confirmed finite element model was established for the future studies.