# US 2024/0280423 A1 · Optical fiber-embedded pc steel strand, strain measurement device, and production method for optical fiber-embedded pc steel strand > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2024/0280423 A1 - Document ID: US20240280423A1 - Status: Published application - Kind: A1 - Application number: 18/570,786 - Filed: 2022-05-11 - Published: 2024-08-22 - Earliest claimed: 2021-08-20 - Assignees: Sumitomo Electric Industries, Ltd. - Applicants: Sumitomo Electric Industries, Ltd. - Inventors: Noboru UEDA; Youji NAKAI; Katsuhito OSHIMA; Yoshiyuki MATSUBARA; Motonobu NISHINO; Masashi OIKAWA; Shinji NAKAUE; Naoki SOGABE; Michio IMAI; Toru YAMAMOTO; Shinichi YAMANOBE; Kazumasa OKUBO - Web page: https://patentgrep.com/patent/US20240280423A1 ## CPC - D07B 1/145: {comprising elements for indicating or detecting the rope or cable status} - G01L 1/242: {the material being an optical fibre} - D07B 1/0693: {having a strand configuration} - E04C 5/08: Members specially adapted to be used in prestressed constructions {(production of reinforced objects in general B28B23/00; prestressed structures produced in situ E04G21/12)} - E04G 21/12: Mounting of reinforcing inserts; Prestressing (shell tubes for prestressing members E04C5/10; anchoring means E04C5/12; connections of reinforcing elements and spacers E04C5/16) - G01B 11/18: {using photoelastic elements} - G02B 6/44: Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables (cables incorporating electric conductors and optical fibres {where features relating to the optical fibres are not of interest} H01B11/22) - D07B 2201/2096: Light guides - D07B 2501/2023: Concrete enforcements - D07B: ROPES OR CABLES IN GENERAL (joining ropes or cables to one another or to other objects B65H69/00, F16G11/00; {mountaineering ropes A63B29/02}; mechanical finishing or dressing of ropes D02J; {braiding D04C}; decorative ropes or cords D04D; suspension cables for bridges E01D19/16; specially adapted for driving, or for being driven by, pulleys or other gearing elements F16G9/00; electric cables or joints insofar as electrical aspects are essential H01B, H01R) - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - E04C: STRUCTURAL ELEMENTS; BUILDING MATERIALS (for bridges E01D; specially designed for insulation or other protection E04B; elements used as building aids E04G; for mining E21; for tunnels E21D; structural elements with broader range of application than for building engineering F16, particularly F16S) - E04G: SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An optical fiber-embedded PC steel strand includes a PC steel strand in which a plurality of PC steel wires are twisted together, and an optical fiber. The optical fiber is fixed with a resin in a twist groove that is a groove between two PC steel wires of the PC steel wires, the two PC steel wires being disposed at an outer surface of the PC steel strand and being next to each other. A coefficient of variation in distance between a common tangent of the two PC steel wires that form the twist groove and are next to each other, and a center of the optical fiber is 0.5 or less, as measured in 10 cross sections of the PC steel strand that are perpendicular to a longitudinal direction of the PC steel strand. ## Claims ### Claim 1 An optical fiber-embedded PC steel strand, comprising: a PC steel strand in which a plurality of PC steel wires are twisted together; and an optical fiber, wherein the optical fiber is fixed with a resin in a twist groove that is a groove between two PC steel wires of the PC steel wires, the two PC steel wires being disposed at an outer surface of the PC steel strand and being next to each other, and a coefficient of variation in distance between a common tangent of the two PC steel wires that form the twist groove and are next to each other, and a center of the optical fiber is 0.5 or less, as measured in 10 cross sections of the PC steel strand that are perpendicular to a longitudinal direction of the PC steel strand. ### Claim 2 (depends on 1) The optical fiber-embedded PC steel strand according to claim 1, wherein in the cross section of the PC steel strand perpendicular to the longitudinal direction of the PC steel strand, the optical fiber is positioned in a region enclosed by a straight line that is parallel to the common tangent and 0.1 mm apart from the common tangent inward of the PC steel strand, and surfaces of the two PC steel wires that form the twist groove and are next to each other. ### Claim 3 (depends on 1) The optical fiber-embedded PC steel strand according to claim 1, wherein in the cross section of the PC steel strand perpendicular to the longitudinal direction of the PC steel strand, an outer surface of the optical fiber is coated with the resin. ### Claim 4 (depends on 1) The optical fiber-embedded PC steel strand according to claim 1, wherein the optical fiber-embedded PC steel strand includes two or more optical fibers. ### Claim 5 (depends on 1) The optical fiber-embedded PC steel strand according to claim 1, wherein an elongation at break of the resin is 3.5% or more. ### Claim 6 (depends on 1) The optical fiber-embedded PC steel strand according to claim 1, wherein the optical fiber-embedded PC steel strand includes an anticorrosive coating that coats the outer surface of the PC steel strand. ### Claim 7 (depends on 1) A strain measurement device, comprising: the optical fiber-embedded PC steel strand according to claim 1; and a scattering light measurement device connected to the optical fiber-embedded PC steel strand. ### Claim 8 (depends on 7) The strain measurement device according to claim 7, wherein the scattering light measurement device includes an interface configured to output measurement data. ### Claim 9 A production method for an optical fiber-embedded PC steel strand, the production method comprising: disposing an optical fiber in a twist groove that is a groove between two PC steel wires of a plurality of PC steel wires twisted together to form a PC steel strand, the two PC steel wires being disposed at an outer surface of the PC steel strand and being next to each other; and fixing the optical fiber in the twist groove with a resin, wherein in the disposing, a tension of more than 0 N and 20 N or less is applied to the optical fiber. ### Claim 10 (depends on 9) The production method for the optical fiber-embedded PC steel strand according to claim 9, wherein the production method includes supplying the resin to the twist groove after the disposing and before performing the fixing. ### Claim 11 (depends on 9) The production method for the optical fiber-embedded PC steel strand according to claim 9, wherein a curing time of the resin is one minute or shorter. ### Claim 12 (depends on 9) The production method for the optical fiber-embedded PC steel strand according to claim 9, wherein the resin is a UV-curable resin, and in the fixing, the resin is irradiated with ultraviolet rays.