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Method and apparatus for in situ assemblage of a strain sensor in erected structural elements

  • US 4,738,135 A
  • Filed: 12/15/1986
  • Issued: 04/19/1988
  • Est. Priority Date: 12/15/1986
  • Status: Expired due to Term
First Claim
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1. A method of in situ press-fit assembly of a cylindrical strain sensor in a portion of a structural steel element, said cylindrical strain sensor having a central maximum diameter portion and at least one reduced-diameter end portion, comprising the steps of:

  • (1) providing a guide block having a central hole with a diameter less than the maximum diameter of the cylindrical strain sensor by an amount equal to the desired press-fit interference, and a counterbore sized to freely receive an end portion of said cylindrical strain sensor therein, a pair of unthreaded bolt holes radially spaced from said central hole, and a plurality of threaded holes disposed in peripherally spaced relation to said central hole;

    (2) fabricating a template having center punch indications respectively alignable with the axes of said center hole and said unthreaded said bolt holes;

    (3) abutting said template with the portion of the structural steel element where stress determination is desired;

    (4) center punching hole locations in said portion through said center punch indications in said template;

    (5) drilling a pilot hole at said center punch location corresponding to said central hole to a diameter less than the maximum diameter of said cylindrical strain sensor;

    (6) drilling holes at each center punch location of said unthreaded bolt holes to a diameter equal to said unthreaded bolt holes;

    (7) securing said guide block to the surface of said portion by bolts snugly traversing said unthreaded holes in said guide block and the aligned holes in said portion of the structural steel element, and securing said bolts with nuts applied to the ends of said bolts projecting through the structural steel element;

    (8) inserting a counterbore reamer through said center hole of said guide block and finishing said pilot hole in said portion of the structural steel element to a diameter less than the maximum diameter of said cylindrical strain sensor by an amount equal to the desired press-fit interference;

    (9) removing said guide block from said portion of the structural steel element;

    (10) inserting a reduced-diameter end portion of said cylindrical sensor in said finished hole in said portion;

    (11) reassembling said guide block to said portion with said maximum diameter portion of said cylindrical sensor disposed in said counterbore;

    (12) inserting a force-transmitting bushing in said central hole in said guide block with one end of said bushing projecting out of said central hole;

    (13) securing a push plate across the projecting end of the said force-transmitting bushing by bolts traversing the push plate and threaded into said threaded holes of said guide block; and

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