Experimental investigation of the effects of impact damages on the performance of high-strength beams

The aim of this study is to determine the change in bending and shear capacity of high strength reinforced concrete (RC) beams with different ductility capacities which have been subjected to different impact energies but have not lost their bearing capacity completely. In order to determine the change in bending and shear capacities caused by impact effects, bending tests were also performed after impact tests on beams. Thus, the changes in the behavior of RC beams were examined by comparing the experimental results of a reference reinforced concrete beam which was not subjected to impact effects. In the experimental study, residual load and moment carrying capacities, displacement and rotational ductilities, bending rigidities, energy absorption capacities, maximum shear crack widths and deformations of reinforcements (tension, compression, and shear) were determined after the impact effects. Additionally, the experimental rotations and shear strengths of beams are compared with the limit rotation values and theoretical shear strengths given in TBEC 2018 and ACI 318-14. In addtion to, appropriate intervention methods, such as repair, strengthening, and reconstruction have been recommended according to the damage intensity for the behavior of impact damaged high-strength RC beams. This thesis consists of three main stages. In the first stage of the experimental study, pilot experiments were performed and energy levels were defined depending on the free fall height and the mass of the impactor. In this thesis, different impact energies were obtained using different mass of impactor or different free fall height likewise the literature. In the second stage of the experimental study, the dimensions and reinforcement ratios of the test specimens were determined considering results of the pilot tests and the impact tests were performed. The dimensions, concrete compressive strength, transverse reinforcement and a/d ratios of the specimens used in the experiments were kept constant and only the longitudinal tension reinforcement ratios were changed to represent the five different behavior of RC beams changing from ductile to brittle manner. In the final stage of the experimental study, static flexural tests of both reference and impacted specimens were carried out to examine comparatively the relationship between the change in the behavior of high-strength reinforced concrete beams and the impact effect, the residual load bearing capacity and the change in ductility of the beams.