Experimental study of mixed-mode crack propagation in RC beams without stirrups

This paper presents the results of a very recent experimental research program aimed at investigating mixed-mode fracture of longitudinally reinforced concrete beams. The tests were designed so that only one single mixed-mode crack generates and propagates through the specimen, as opposed to the usual dense crack pattern found in most of the tests in scientific literature. The specimens were three-point-bend beams of three different sizes. They were notched asymmetrically and reinforced with various ratios of longitudinal reinforcement. These experiments may help to understand the mechanisms of mixed-mode crack propagation in longitudinally reinforced concrete elements. Finally an analytical model based on the experimental results model is presented to analyze size effect and hyper-strength in this kind of elements.