In this paper, the writer reports the result of investigations of 82 paino wire concrete girders of 32 kinds which were carried out during the years from 1944 to 1948.
By referring to literature on the subject published in foreign countries the writer has determined the subjects to be studied hereafter and has investigated experimentally the method of manufacturing piano wire concrete girders and their properties.
From these experiments conclusions have been drawn on
1) the girder manufacturing equipment and the essential points of its manufacturing,
2) required properties of concrete and piano wire which are to be used for piano wire concrete,
3) method of calculating the initial stress and cracking load,
4) effect of the contraction and creeping of concrete upon the girders,
5) bond strength between piano wire and concrete,
6) method of calculating the breaking load of the girders,
7) strengthening against breakage due to diagonal tension of the ribs,
8) standards for designing and manufacturing of the girders.
For a piano wire concrete railway bridge of 2.75m span which is designed on the basis of the result of the writer's investigations, concrete of 46% and steel of 20% of an ordinary reinforced concrete bridge have been found sufficient.

View full abstract