Abstract
We have sampled 1085 concrete core specimens from 91 existing reinforced concrete buildings and tested the qualities of these concrete core specimens. In this paper (Part 1), the actual conditions of the average value of compressive strength, Young's modulus and air-dried weight of unit volume of concrete in each building are investigated. The main results of this paper are as follows. 1) The average value of concrete strength in each building shows a tendency to increase with the completed year of building. 2) The standard deviation in the distribution of concrete strength in each building shows a tendency to decrease after the SHOWA 40's. 3) The peak of the stochastic distribution of compressive strength of concrete in the typical building has a tendency to the small side of strength. 4) Young's modulus and air-dried weight of unit volume of concrete show a tendency to decrease with the completed year of building and in the TOHOKU district.
