In recent days, the quality of some centrifugal concrete electric poles in Ha Tinh has become the focus of public opinion, after many poles were broken due to storm Bualo, exposing the internal structure and causing much debate.

Ha Tinh Electricity Company said that these electric poles are part of the project to upgrade the 35kV power line and 35/0.4kV transformer station at the Dong Loc T-junction relic site. The project was implemented in 2013, technically accepted in April 2014, energized and put into operation in July 2014 to ensure safe and stable power supply for the relic site and the people.

In the project, the construction unit used centrifugal concrete columns produced by Khanh Vinh Company Limited.

In the document Design of centrifugal reinforced concrete electric poles dated January 2, 2013, this company has presented and applied new technology in the production of shaped steel concrete poles.

electric switch
The electric pole was broken by storm Bualoi, revealing the details inside, causing a stir in public opinion. Photo: Social networks

According to documents of Khanh Vinh Company Limited, Vietnam is gradually modernizing the national power grid system, especially the rural power grid system, remote areas with many rivers and high mountains. Therefore, transportation and construction are extremely difficult, there are no specialized transport vehicles, so the quality of the power poles is greatly affected.

To overcome the above factors, the company has applied reinforced concrete technology (hard reinforced concrete).

The company cited research and experimental results showing that: if the steel structure is arranged properly, the rigid steel column concrete structure can withstand great force and still ensure safety even when the concrete part is damaged.

After many tests, shaped steel has been applied to the production of centrifugal electric poles and concrete square poles, showing high load-bearing capacity and reliability. Thanks to that, this structure helps increase horizontal stiffness and improve the stability of the entire structure.

The company's documents indicate that previously, the structural steel solution has been used effectively in constructions in many countries located in earthquake zones, because they have a high level of stability and reliability when bearing earthquake loads. This has been verified in practice, especially the earthquake in Kobe, Japan.

Khanh Vinh Company also revealed that in early 2014 the company would produce a new type of lightweight concrete reinforcement product with the same size and cross-section but with a weight reduction of 20-25%.

In the calculation of rigid steel column structure under compression and bending ACI318 (construction standard of American Concrete Institute) and ASIC-LRFD, Khanh Vinh Company Limited clearly states the regulations on column structure: Arrangement of rigid reinforcement to create the load-bearing capacity of the structure even when the concrete is damaged, while improving the flexibility of the structure when designing structures that can withstand heavy loads.

It is possible to design the concrete part to absorb most of the load, especially the earthquake load and be able to be damaged. The rigid part will bear the static load of the structure and create a certain stiffness, reducing the risk of collapse of the structure.

According to the documents of Khanh Vinh Company Limited, the calculation regulations of ACI318 for rigid concrete columns are similar to those for normal steel concrete column structures. It is worth mentioning that the results of many tests show that with the same cross-section of reinforcement in a structure, if the shaped reinforcement is designed and arranged reasonably, the column head force will be greatly increased.

Ha Tinh Electricity Company spoke up about the case of a broken concrete electric pole revealing details that attracted attention . Ha Tinh Electricity Company proactively provided documents to the police to coordinate the inspection, and at the same time worked with Khanh Vinh Company Limited to request a review of documents, inspection, and re-testing of technical indicators.

Source: https://vietnamnet.vn/vu-cot-dien-gay-do-o-ha-tinh-he-lo-ban-thiet-ke-chiu-duoc-ca-dong-dat-2448344.html