2018 Volume 86 Issue 1 Pages I_19-I_25
We evaluated the influence of a change in product specification (namely, an increase in standard strength) on the cross-sectional stiffness (CSS) of centrifugally reinforced concrete (RC) pipes. Because different manufacturers make RC pipes in different ways, we evaluated the CSS of RC pipes made by various companies and the stiffness deterioration characteristics of the pipes at the time of crack occurrence. The CSS of RC pipes complying with the previous Japanese Industrial Standards (JIS) was 28% less than that of pipes complying with the current JIS. The main factor in this difference is thought to be different values of elastic modulus of the concrete used. In addition, RC pipes made by different manufacturers showed differences in CSS before and after the initial cracking. We confirm that deteriorations such as cracking and reduced thickness lower the CSS of RC pipes. Overall, the results of this research revealed that the stiffness of RC pipes in service must be evaluated considering their manufacturer and the industrial standard with which they comply.