Abstract
In this paper (Part 2), the variation of concrete qualities between the types of element and between stories are investigated. The main results are as follows. 1) The variation of compressive strength of concrete between the types of elements is 25kg/cm^2 at most. 2) Compressive strength increases at a rate of about 13kg/cm^2 per 1 meter depth of placing concrete in the column and in the wall. But the variation of concrete strength at the points of the same depth in the same element is about 40kg/cm^2 and that value is very large in comparison with the variation by the depth. 3) The variation of concrete qualities in existing reinforced concrete building is most influenced by the variation of original concrete qualities placed in the structure. 4) In the middle and small size reinforced concrete building, the within story variation of compressive strength of concrete in structure by core specimens is analogical to the within day variation of 28 days compressive strength by field water cured specimens and the between stories variation is analogical to the between day variation. The within story variation is 1.8 times as large as the within day variation, but the between stories variation is nearly equal to the between day variation.
