Issue 49

Y. Liu et alii, Frattura ed Integrità Strutturale, 49 (2019) 714-724; DOI: 10.3221/IGF-ESIS.49.64 721 t t n X K X  (3) where K t is the carbonization influence coefficient of bending-tension stress, X t the carbonization depth of concrete under bending load in the tension zone; and X n the carbonization depth of concrete without any load in the tension zone. Through regression analysis, the equation describing the carbonization influence coefficient of bending-tension stress and bending load stress level under different fly ash contents is shown Tab. 5, where K t is the carbonization influence coefficient of bending-tension stress and St the bending load stress level. Figure 6: Relationship between carbonization depth in the concrete compression zone and bending-compression load stress level in different carbonation periods Fly ash content Fitting equation Correlation coefficient R 0% 0.9049 1.0234 t S t K e  0.91 20% 0.742 1.0266 t S t K e  0.92 30% 0.7268 1.0356 t S t K e  0.95 40% 0.683 1.0614 t S t K e  0.91 Table 5: Equation of the carbonization influence coefficient of bending-tension stress Tab. 5 shows the exponential relationship between the carbonization influence coefficient of bending-tension stress and the bending load stress level, which is different from the results of the quadratic polynomial relationship in reference [16] . This is probably due to the fact that the test materials in the reference were plain concrete blocks and that the research did not consider the effect of steel bars. Carbonization influence coefficient of bending tension-compression load To study the relationship between the bending-compression zone and the bending-tension zone of the reinforced concrete block under bending loads, this paper analyzed and compared the different mechanical characteristics, crack development mechanisms and carbonization depths of the two zones under bending loads.