Preparation and Reasons for Slippage of Prestressed Anchorages
Prestressed anchorages are widely used in railways, highways, bridges, and other projects. In order to better avoid problems in use, it is important to understand the knowledge of prestressed anchorages. So do you know what preparations need to be made before the use of prestressed anchorages? What are the reasons for slippage? The following is an introduction to the preparation items of the prestressed anchorage and the reasons for the wedge slippage.
Prestressed Anchorage Preparation Before Use
Prestressed anchorages must undergo certain inspections and preparations before use to avoid problems in use. So what preparations should be made before using it? Next, the prestressed anchorage manufacturer will give you a brief explanation.
1. Static load test
According to the requirements of engineering construction, there are many methods of static load tests and the indicators will be different. Before the prestressed anchorages are used, the construction unit should conduct static load tests on the performance requirements of the anchorages in accordance with the specific conditions of the construction.
2. Hardness range detection
This kind of detection is very common. Generally, 5% of the anchors and no less than 5 sets are selected from each batch, and the hardness test is performed on the parts with hardness requirements. For the wedge of the multi-strand anchor, at least 5 pieces shall be taken from each set. Each part is tested at 3 points and its hardness should be within the range of design requirements. If one part is unqualified, another double number of parts shall be taken and the test shall be repeated. If there is still a part that is unqualified, it should be checked one by one, and it can be used after it is qualified.
3. The anchorages, grips, and couplers for prestressing tendons must be cleaned before installation. If it is necessary to apply a substance that does not affect the anchoring performance on the anchoring parts according to the design regulations, it should be applied in time before installation.
4. In order to ensure that the prestressed anchorages and couplers are aligned with the duct during installation, the bearing plate shall be provided with a centering stop or a centering mark.
5. Anchorages, grips, and couplers should be protected from corrosion, soiling, mechanical damage, and confusion.
Above, we have briefly explained the inspection work that should be done before using the prestressed anchorage. Don’t ignore it when using it, so that it can be used more safely.
Analysis of the Slip of Prestressed Anchorage
Prestressed steel strands are mainly used in railways, highways, bridges, water conservancy and hydropower dams, and other fields. The thread may slip or break during use. What’s the matter? Next, we briefly analyze the reasons.
1. Defects on the wire surface. Strand breakage usually occurs when there are obvious scratches and cracks on the wire surface.
2. Inaccurate placement of the anchor head, the tilt of the supporting pad, and improper installation of the stressing jack will cause the prestressed strand to break or even the wedge to break.
3. Center inclusions. Inclusions are mainly of calcium aluminate type, which is produced during the deoxidation process of steelmaking. The presence of non-metallic inclusions in the wire destroys the continuity of the organization and the matrix, instantaneously breaking, and forming broken wires.
4. The diameter of the actual prestressed steel wire or prestressed steel strand is too large, the anchor head and the wedge are not closely attached, and the wire breaks or slips during tension.
Henan Zhongjiao Road&Bridge Engineering Materials Co., Ltd specializes in producing the post-tensioning system for over 10 years. If you want to know more about prestressed anchorages, welcome to consult email@example.com.