The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 11, 2001
Filed:
Nov. 29, 2000
Bernard Basile, Plaisir, FR;
Bruno Lancia, Marseille, FR;
Abstract
In order to measure in situ the residual tension F,of a pre-stressed bar braced between two anchorages, the two-way propagation time T,of an ultra-sonic wave between the two ends of the bar is measured, and F,is evaluated by the formula F,=F,+k,.(T,−T,). During a preliminary calibration carried out without demounting, the bar is subjected to a variable traction effort F. For each value, the two-way propagation time T of an ultra-sonic wave between the two ends of the bar is measured, a curve associating the effort F with the time T is recorded, and the constant T,is determined as being the two-way propagation time measured for F=0, the curve is approached in the neighborhood of the value F=0 by a first straight line of slope k,, an upper portion of the curve is approached by a second straight line of slope k,, the constant F,is determined as being the traction effort F corresponding to the point of intersection of the first and second straight lines, and the constant k,is determined according to the relationship,/k,=(,/k,)−(,/k,).