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Flexural cracking behavior and calculation approach of reinforced highly ductile fiber-reinforced concrete beams

Zhang Min, Deng Mingke, Wu Zhiyan, Pan Jiaojiao

Archives of Civil and Mechanical Engineering

2021

Vol. 21, no. 4

320--333

Highly ductile fiber-reinforced concrete (HDC) is a class of cementitious composites reinforced with polyvinyl alcohol (PVA) fibers and exhibits strain-hardening behavior and multiple fine cracks under tension. This study aims to evaluate the cracking behavior and propose a simple calculation approach of the crack width and crack spacing of reinforced HDC (RHDC) flexural members. The four-point bending tests were conducted for RHDC beams with a different ultimate tensile strain of HDC and tensile reinforcement ratio. The flexural cracking performance of beams was mainly analyzed. The results showed that the width, spacing, height of flexural cracks of RHDC beams was significantly smaller compared with those of reinforced concrete (RC) beams. An increase in the ultimate tensile strain of HDC decreases the crack width and crack height while has little influence on the average crack spacing of RHDC beams. The effect of the tensile reinforcement ratio on the crack width is notable for RHDC beams with a higher ultimate tensile strain of HDC. The increasing of the tensile reinforcement ratio decreases the average crack spacing and crack height of RHDC beams. Furthermore, theoretical formulas for the average crack spacing, average crack width, and maximum crack width of RHDC beams were proposed based on the bond interaction between rebars and HDC and the fiber bridging stress. The predicted values have good agreement with the experimental values, indicating that the proposed method is reliable to evaluate the crack behavior of RHDC flexural members. Based on an accurate validation, the effect of cover thickness, HDC strength, and rebar diameter on the crack behavior of RHDC beams was conducted and found consistent with the law of RC beams.

Identification of parameters of concrete damage plasticity constitutive model

Jankowiak T., Łodygowski T.

Foundations of Civil and Environmental Engineering

2005

No. 6

53-69

The paper presents a method and requirement of the material parameters identification for concrete damage plasticity constitutive model. The laboratory tests, which are necessary to identify constitutive parameters of this model have been presented. Two standard applications have been shown that test the constitutive model of the concrete. The first one is the analysis of the three-point bending single-edge notched conrete beam specimen. The second presents the four-point bending single-edge notched conrete beam specimen under static loadings. In conclusion, the comparison of crack patterns in the numerical and laboratory [2,9] tests has been presented and discussed.

W pracy przedstawiono metodę identyfikacji parametrów materiałowych betonu klasy B50. Przyjęto model matematyczny betonu plastycznego ze zniszczeniem. Określono, jakie testy laboratoryjne są niezbędne do identyfikacji parametrów konstytutywnych tego modelu. Przetestowano użyteczność modelu konstytutywnego w wybranych dwóch zadaniach brzegowych (zginanie trójpunktowe oraz czteropunktowe belki betonowej z nacięciem). Porównano otrzymane mechanizmy zniszczenia ze znanymi wynikami eksperymentów laboratoryjnych [2, 9].