Method of eliminating and uneven stress distribution in an elongated reinforced member
OwnerBirger Ludvigsoninventor
Life of this patent
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Abstract
Reinforcing members of concrete structures are often tensioned against a considerable frictional resistance, which causes an uneven stress distribution along the member. This means that the reinforcing capacity of the member is unsatisfactorily utilized. To obtain a more even stress distribution the tensioning operation is terminated by a sudden, measured release of tensioning force, resulting in a shock wave progressing along the member.
Claims13
A method of eliminating an uneven stress distribution in an elongated reinforcing member in a concrete structure caused by tensioning said member against a frictional resistance, comprising
- a. imposing about the desired amount of tensioning upon the member, and
- b. thereafter suddenly subjecting the member to a measured amount of strain force change.
A method of ensuring an even stress distribution in an elongated reinforcing member fitted into a passage in a concrete structure comprising the steps of
- a. connecting at least one end of said reinforcing member to a pressure fluid operated ram,
- b. imposing an amount of tensioning upon said member by at least one stroke of said ram, thereby causing an uneven distribution of stresses in said member along the length thereof due to said member being subjected to frictional resistance resulting from the contact between said member and the wall of said passage, and then
- c. relieving said uneven stress distribution by suddenly connecting said ram to a pressure fluid tank to cause an instantaneous change in the force acting upon said member thereby initiating a shock wave propagating therethrough.
A method of manufacturing a post-stressed concrete structure, comprising the steps of
- a. casting the structure and preparing therein at least one passage, for the reception of an elongate reinforcing member,
- b. connecting at least one end of said reinforcing member to a pressure fluid operated ram,
- c. imposing an amount of tensioning upon said member by at least one stroke of said ram, thereby causing an uneven distribution of stresses in said member along the length thereof due to said tensioning being subjected to frictional resistance resulting from the contact between said member and the wall of said passage,
- d. relieving said uneven stress distribution by suddenly connecting said ram to a pressure fluid tank to cause an instantaneous change in the force acting upon said member thereby initiating a shock wave propagating therethrough,
- e. filling the channel around said strengthening member with a cement slurry, and
- f. permitting said slurry to settle and finally releasing the external tensioning force on the member.
Dependencies are inferred from the claim text.