What Are the Causes of "Slippage" and "Breakage" in Prestressed Steel Wire Construction?

In prestressed steel wire construction, "slippage" and "breakage" are common problems that directly impact project quality and structural safety. They can not only lead to loss of prestress and reduced component load-bearing capacity, but can also cause rework and even pose safety hazards. This article deeply analyzes the causes of these two types of problems from four core perspectives: product quality, construction operations, equipment status, and environmental adaptability. This article provides professional guidance for risk mitigation in construction projects and helps improve the reliability and safety of prestressed steel wire construction.

I. Basic Cause: Substandard Product Quality

1. Prestressed Steel Wire Defects: Wire mechanical properties (tensile strength, elongation, and relaxation) fail to meet national standards, or problems such as surface cracks, corrosion, excessive diameter deviation, and poor material uniformity can lead to wire breakage during tensioning due to localized overload or insufficient performance. Furthermore, dimensional or performance abnormalities can reduce compatibility with the anchor, indirectly causing wire slippage.

2. Anchor Clip Issues: Mismatched anchor and wire specifications, insufficient machining accuracy (such as taper deviation) or hardness, and the use of non-original anchors and clips can directly weaken the anchor's grip on the wire, leading to wire slippage during tensioning or later in use.

II. Main Contributing Factor: Irregular Construction Operations

1. Improper Pre-tensioning Preparation: Failure to thoroughly clean the wire surface of oil, rust, and impurities within the anchor; skewed clips and offset anchors during installation; insufficient wire straightness and disordered arrangement. These can result in uneven stress distribution during tensioning, localized stress concentration leading to wire breakage, or insufficient friction at the contact surface leading to wire slippage.

2. Irregular Pre-tensioning Operations: Failure to perform staged tensioning according to specifications (e.g., tensioning to the design stress in one go); excessive tensioning exceeding 10% of the design stress; and failure to monitor wire elongation in real time (failure to promptly investigate when actual elongation deviates from the theoretical value by more than ±6%). These can lead to instantaneous overload or uneven stress distribution on the wire, directly causingwire breakage.

3. Untimely Post-tensioning Treatment: Failure to allow the required 10-15 minutes of rest before re-tensioning can easily lead to prestress loss. Furthermore, failure to promptly perform anti-corrosion treatment on the anchor can create the potential for rust and wire slippage later on.

III. Hidden Risks: Abnormal Equipment Condition

1. Inaccurate Tensioning Equipment: Failure to calibrate the jack and oil pressure gauge as required (every six months or after 200 tensioning cycles), or excessive calibration errors, as well as equipment failures such as oil leaks and instrument jams, can lead to inaccurate tensioning stress control, with actual stress far exceeding or falling short of the design value, causing wire breakage or slippage due to prestress loss.

2. Damaged Auxiliary Tools: Wear and deformation of clips due to repeated use, damage to guide devices causing wire deviation during tensioning, or mismatched specifications between the tool anchor and the working anchor can result in uneven stress on the wire, reducing the anchor's grip and potentially causing slippage or breakage.

IV. Scenario Risk: Unsuitable Environmental Conditions

1. Highly Corrosive Environments: When working in humid, saline, or other corrosive environments, if temporary corrosion protection measures (such as wrapping with rainproof cloth or applying rust inhibitors) are not implemented on the steel wire and anchors, surface rust will occur. This will reduce the grip between the anchor and the wire, leading to wire slippage. Furthermore, the cross-sectional area of the wire will be reduced, resulting in a decrease in tensile strength and wire breakage.

2. Low Temperature Environments (<5°C): Low temperatures will embrittle the steel wire and reduce its tensile toughness, making it prone to cold brittle wire breakage during tensioning. Furthermore, low temperatures will reduce the tightness of the clamps and the wire, resulting in insufficient grip and an increased risk of wire slippage.

3.High Temperature Environments (>35°C): High temperatures will cause the tensioning equipment oil temperature to overheat, leading to unstable hydraulic system pressure and resulting in tensioning stress deviation. Furthermore, due to thermal expansion and contraction of the wire, the prestress will be lost when the temperature drops, further causing wire slippage.

As a supplier deeply engaged in the prestressed steel industry, we not only provide core products such as prestressed steel wire and anchors that meet national standards, but also offer professional selection guidance and construction technical support tailored to specific application scenarios. From product quality to construction implementation, we help you avoid the risks of wire slippage and wire breakage throughout the entire process. If you need to develop a risk mitigation plan for a specific project scenario or learn more about prestressed steel product selection, we are ready to provide support. You can contact us via the phone number and email address listed on our official website.