| 摘要 |
804,153. Pre-stressed concrete. WESTFALISCHE UNION AKTIENGESELLSCHAFT FUR EISEN-UND DRAHTINDUSTRIE. Dec. 6, 1956 [Dec. 7, 1955], No. 37365/56. Class 20(4) Pre-stressed concrete reinforcement comprises corrugated steel wires wherein the height of the corrugations measured from the centre line to the bottom of the wire at a crest is not greater than half the wire diameter and is not less than 0.4 mm. when the wire is fully stressed and expediently the corrugation length does not exceed ten times the wire diameter. Cracks due to compressive 'force are thereby avoided and the length of the wire from the end of the pre-stressed member at which effective force transmission commences is shortened. Advantageously the corrugation length does not exceed five to seven times the wire diameter. Examples are given, in one of which a wire 2 mm. in diameter has corrugations the height of which is 0.8 to 1 mm. with a preferred corrugation length of 25 mm. |
