Method for fabricating wire strand for main cable of suspension bridge

A method for fabricating a wire strand from parallel steel wires for a main cable of a suspension bridge, the method comprising:

• 1) selecting and coloring a steel wire as a marking steel wire which is to be positioned at a vertex of the wire strand of the suspension bridge comprising a plurality of parallel steel wires and having an equilateral polygon section;
• 2) selecting at least one steel wire having a standard length which is to be positioned at one or more vertexes of the wire strand as a standard steel wire to control an overall length of the wire strand of the suspension bridge;
• adopting a length of the standard steel wire of the wire strand in an unstressed state as a reference, determining position markers at positions of the standard steel wire corresponding to control points of splay cable saddles, center points of main cable saddles, middle points of side spans, a middle point of a middle span, and starting points being one meter away from anchor heads of anchor spans of the suspension bridge;
• calculating operation corrections corresponding to the position markers of the standard steel wire subject to error factors;
• loading and stretching the standard steel wire of the wire strand in an unstressed state on a baseline in a construction field;
• measuring ambient temperature, and correcting errors of the operation corrections resulting from temperature, stress, and sag;
• calculating and checking position displacement corresponding to the position markers of the standard steel wire;
• and drawing, according to design requirements, the position markers at positions of the standard steel wire corresponding to control points of splay cable saddles, center points of main cable saddles, middle points of side spans, the middle point of the middle span, and starting points being one meter away from anchor heads of anchor spans of the suspension bridge;
• 3) loading coils of steel wires having the same double length and the same rotation direction to a pay-out stand;
• regulating a tension of each coil of the steel wires and shaping a cross section of the steel wires by using a rolling mold comprising shaping wheels and having a hexagonal cross section to yield a prefabricated wire strand comprising a plurality of parallel steel wires;
• shaping and wrapping the prefabricated wire strand comprising the parallel steel wires at equal intervals by a wrapping bandage;
• wherein the parallel steel wires comprise feature points corresponding to control points of splay cable saddles, center points of main cable saddles, middle points of side spans, the middle point of the middle span, and starting points of anchor heads of anchor spans of the suspension bridge, and steel wire hoops and shaping clips are disposed on the features points of the parallel steel wires;
• 4) designing dimension and cross section of the prefabricated wire strand according to dimensions of inner cavities of the main cable saddles and the splay cable saddles;
• shaping positions of the prefabricated wire strand corresponding to the main cable saddles and the splay cable saddles by a shaping machine to present a target cross section shape corresponding to the shapes of the inner cavities of the main cable saddles and the splay cable saddles, and then respectively fixing the positions of the wire strand corresponding to the main cable saddles and the splay cable saddles using retaining clips repeatedly;
• wrapping fixed positions of the strain by wrapping bandages, thus achieving preforming of the positions of the wire strand corresponding to the main cable saddles and the splay cable saddles to ensure the shape of the cross section of the wire strand to match the shapes of the inner cavities of the main cable saddles and the splay cable saddles thus mounting the wire strand in the saddles;
• 5) coiling the wire strand comprising the parallel steel wires by a coil frame, wherein a coil diameter is equal to or larger than 30 folds diameter of the wire strand;
• and
• 6) casting anchor of the wire strand comprising parallel steel wires using a zinc-copper alloy or zinc-copper-aluminum alloy and an anchor device which is a main structure to transmit a cable tension of the wire strand comprising the parallel steel wires to an anchor system.