Rheological-dynamical model of concrete and its application on RC beams

Abstract

An improved analytical model based on rheological-dynamical analogy (RDA) is briefly explained and used for the analysis of concrete cylinders under compression. The approach involves standard mechanical properties such as compressive strength, elastic modulus, concrete density and Poisson's ratio for the prediction of both the ascending and the descending branch of the stress-strain curve. Our own experimental data for arbitrarily selected high strength concrete with high deformability was analyzed. Further, the validity of the RDA model is checked against tests of other authors for one normal concrete and for six recycled aggregate concrete mixtures. To demonstrate the capabilities of the improved model, using analytically established stress-strain relations for analyzed samples, the moment-curvature relations and ductility of reinforced concrete beams in bending were numerically examined. The analysis showed that the ductile behavior of beams made of concrete with recycled aggregate can be achieved by limiting the reinforcement ratio to 0.01 if the recycled concrete aggregate is used and to 0.02 for recycled brick aggregate.

Modeling of porous-hardened concrete by rheological-dynamical analogy

“…A large number of experiments have shown that the degree of saturation affects the elastic properties of wet concrete and that the strength of saturated concrete decreases, while the modulus of elasticity of saturated concrete increases compared to dry samples (Wang and Li, 2007), (Zhou et al ., 2016) and (Milašinović et al ., 2022c).…”

“…A large number of experiments have shown that the degree of saturation affects the elastic properties of wet concrete and that the strength of saturated concrete decreases, while the modulus of elasticity of saturated concrete increases compared to dry samples (Wang and Li, 2007), (Zhou et al, 2016) and (Mila sinovi c et al, 2022c). Experimental data in Yaman et al (2002a) were obtained on concrete samples with different amounts of entrained air and different water-cement ratios.…”

Fatigue damage in bending of reinforced concrete frames using non-destructive tests for dynamic strength of the cylinder

“…Before any compressive strain reaches the value εc1 at the compressive strength fcS, the analysis is trivial. After the strain εc1 has been surpassed, the corresponding analysis is explained in Milašinović et al (2020a). In Figure 7, id is the depth of the compression zone, whereas d is the effective depth of the beam.…”

“…Dynamic properties of the concrete cylinders calculated by the resonance method in Section 4.1 indicate that compressive strength is reached when the damage variable D c is equal to 0.5, whereas the damage variable of D soft = 0.86 represents the lowest point on the softening branch of the quasi-static diagram (Milašinović et al , 2020a).…”

“…The frame ductility in bending is defined in strain-softening and is a key parameter for the procedure of dimensioning of the reinforced frame cross-section. The coordinates of the diagrams correspond to the coordinates of diagrams in Figure 10 of the paper (Milašinović et al , 2020a) because the finite rotation βc1 occurs when the bending moment M cr reaches its maximum value.…”