Experimental Study On Size Effect On Flexural Behavior Of Reinforced Concrete Beams

In the reinforced concrete frame structure systems, the flexural behavior at beam ends plays a crucial role in the safety of the structure. The beam end section is doubly reinforced to resist the positive and the negative moment, and locates in the potential plastic hinge region where sufficient ductility and rotation capacity is required. However, the size effect on the flexural behavior of reinforced concrete beams, especially flexural strength, ductility and rotation capacity is still controversial. A majority of the studies available in the literature mainly concerned the size effect on the flexural behavior of the over-reinforced and under-reinforced beams that contain tensile reinforcement only, while few studies on doubly reinforced beams that are widely used in practical projects.In this paper, the size effect on the flexural behavior of reinforced concrete beams which were tested under monotonic and cyclic loading is studied. The depth of specimens is250mm,500mm,750mm and1000mm, respectively. The depth-width ratio of the cross section, shear span ratio and longitudinal reinforcement ratio of specimens, which are casted C40concrete, are constant. Based on the test results, the size effect on the flexural strength, ductility, plastic rotation capacity and energy dissipation capacity of high-strength concrete beams are investigated. Besides, the results are compared with the high-strength concrete beams.Test result is indicated:there is no apparent size effect on flexural strength of reinforced high-strength concrete beams, while displacement ductility ratio, plastic rotation capacity show significant size effect. The energy dissipation capacity shows size effect when the depth of the beams is larger than500mm.