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The Impact of Reduced Pre-stressed Anchor Dimensions on Anchor Quality
Release date:
2019-07-10
In recent years, due to the impact of low-bid winning practices, anchorages have seen their prices decline annually—despite the continuous rise in steel costs. This has left manufacturers with no profit margin, and unfortunately, relevant authorities have yet to implement effective regulatory measures to protect them. As a result, many companies are resorting to cutting corners by reducing material quality. Currently, numerous manufacturers have already shortened the wedge length to 38–40 mm, while also decreasing the thickness, diameter, and hole spacing of the anchorages. Such cost-cutting measures inevitably compromise the overall quality of the products. Yet, every geometric dimension of the anchorage has been meticulously calculated and rigorously tested through countless trials—meaning these dimensions cannot be altered arbitrarily. Otherwise, the stable anchoring performance of the anchorage could be severely compromised. Moreover, both domestic and international experts have discovered that the high-strength steel strands used in the wedges play a critical role in ensuring the long-term reliability and safety of the system.
In recent years, due to the impact of low-bid winning practices, anchorages have seen their prices decline annually despite steadily rising steel costs. This has left manufacturers with virtually no profit margin. Meanwhile, relevant authorities have failed to implement effective regulatory measures to safeguard the industry. As a result, many companies have resorted to cutting corners—such as reducing the length of the wedge to just 38–40 mm—and decreasing the thickness, diameter, and hole spacing of the anchorages. Such cost-cutting measures inevitably compromise the quality of the products. It’s crucial to note that all geometric dimensions of an anchorage are meticulously calculated and rigorously tested through countless trials before finalizing the design. Altering these dimensions arbitrarily could severely undermine the stability and reliability of the anchorage’s gripping performance. Moreover, research conducted by experts both domestically and internationally has revealed that the gripping length of high-strength steel strands within the wedge plays a critical role in determining the overall anchorage performance. If this length is too short, it can lead to strand slippage and significantly weaken the anchorage’s effectiveness. Therefore, the length of the wedge must be strictly controlled—ideally remaining above 50 mm—to ensure optimal performance. Additionally, using anchor plates that are either too small in size or insufficiently thick can jeopardize the anchorage’s load-bearing capacity. For this reason, it is absolutely forbidden to arbitrarily reduce the dimensions of anchorages, as doing so could lead to severe construction accidents.
The main reasons for tensile bursting (in concrete and anchor plates) at the anchorage zone of the anchoring device are as follows:
(1): During concrete pouring, inadequate vibration at the anchorage location resulted in poor compaction of the concrete behind the anchor and anchor plate, creating voids. Consequently, after stress was applied, the concrete around the entire anchor plate burst open.
(2): The anchor plate does not meet the design specifications, or the working anchorage device is incompatible with the anchor plate.
(3): Internal components at the anchorage are either incompletely installed or incorrectly positioned (e.g., spiral reinforcement, rebar mesh, and breakout-resistant bars).
(4): Quality issues with anchor plates or anchoring devices.
(5): Tensioning of prestress exceeds the design stress value.
(6): Concrete has not fully set, or the material mix ratio has not yet reached the design specifications.
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Liuzhou Yuqiao Prestressed Engineering Technology Co., Ltd.
Email:1193915742@qq.com
Address: No. 1 Fengcun Industrial Area, Silian Village, Jinde Town, Liujiang District, Liuzhou City
Phone:0772-3732260
Mobile phone:13978068222
Website address:https://www.yqyyl.cn/
Chinese web address: Yuqiao.Web, Anchorage.Web
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