Abstract
Kanmon PC slabs, which have been used over 53 years, were estimated for the effective prestress based on the Stress-releasing Method. By contrasting three sets of cases, smaller core size and drilling from the greater strain surface, are concluded to make the method more reliable. To examine the method and check inner stress and strain change of the drilled core, a FEM analysis is conducted. Then through the comparison of results with experiment, they can almost coincide, which verifies the reliability of the method. Obtained from both experiment and analysis, strains will be almost released in depth as about 0.3 times of the core's diameter.
