Technical Requirements for Prestressed Steel Strand Anchorage
Prestressed anchorages are widely used in highway bridges, railway bridges, urban interchanges, urban light rail, high-rise buildings, water conservancy and hydropower dams, port wharves, rock and soil protection and anchoring, foundation reinforcement, tunnel mine roof anchors, prestressed grids, subways, and large buildings and halls, warehouses, tower buildings, lifting of heavy objects, intermittent sliding film propulsion, jacking of bridges and tunnels, large vessels and ships, sleepers, replacement of bridge supports, bridge and building reinforcement, steel reinforcement engineering, anti-magnetic, and anti-corrosion engineering (fiber anchors), carbon fiber reinforcement, pre-tensioned beam field construction, external prestressing engineering, stay cables, suspension cables, etc.
Technical requirements for prestressed anchors:
- The variety, standard, and quality of prestressed tendons, anchors, grips, and couplers should conform to the requirements and the rules of current national standards.
- The prestressed tendons should be smooth and free of bending; there should be no cracks, small thorns, mechanical damage, iron oxide scale, and oil stains on the surface.
- The retraction amount of the anchor wedge should not be greater than 6mm, and the total friction loss of the anchor and the bearing plate should not exceed 6%.
- The anchors shall meet the requirements of graded tensioning, supplementary tensioning and relaxation of prestressed tendons. When used in post-tensioning structures, grouting holes or vent holes should be provided on the anchor or its accessories. The position and diameter of the grouting hole should meet the requirements of the grouting process, and there should be a structure connected with the grouting pipe. When a closed cover is used, a connecting structure should be provided on the anchor or its accessories.
- The grips should have an outstanding self-anchor function, loose anchor function, and repeated use function. For the grips that need to be knocked to loosen, it is necessary to ensure that it has no effect on the anchoring of the prestressed tendons and can ensure the safety of the operators.
- The materials used in anchors, grips, and couplers are not less than the requirements of 45# steel and should meet the requirements, with certificates of mechanical function and chemical composition, and quality assurance certificates.
- For anchors used for steel strands with a diameter of 9mm-15.2mm, the minimum diameter and thickness of anchor plates with 1 to 21 holes should conform to the rules of the national stardard.