From the first large cable-stayed bridge built, My Thuan Bridge, inaugurated in 2000, to My Thuan 2 Bridge, which started construction in 2020, is a long 20-year journey.
After that journey, also on the Tien River with heavy alluvium, Vietnamese cadres, engineers and workers gradually learned and mastered construction technology.
It can be said that the Mekong Delta is home to the largest cable-stayed bridges in the country. The first is My Thuan Bridge, which was inaugurated in 2000.
At that time, to build My Thuan bridge connecting Tien river, the Australian government supported part of the capital and technology. The total investment capital of My Thuan bridge at that time was about 90.86 million Australian dollars (equivalent to about 2,000 billion VND), the construction time was 4 years (from 1997 - 2000).
In 2004, when we started building the Can Tho Bridge across the Hau River, we also needed support from Japan in terms of capital, design, and construction technology. This bridge was inaugurated in 2010.
Next, Cao Lanh and Vam Cong bridges also received support from the Korean Government from funding to technical support during construction.
My Thuan 2 Bridge is 350m upstream from My Thuan Bridge. Photo: Nguyen Ro Lil
Rach Mieu Bridge on National Highway 60 connecting Tien Giang - Ben Tre is the first cable-stayed bridge designed and constructed by Vietnamese engineers, with funding from domestic investors. However, in reality at that time, the construction of cable-stayed cables still depended on foreign contractors.
It was not until the My Thuan 2 Bridge was implemented that, with the determination of the Party and State leaders, and in the context of difficult capital sources, the National Assembly still allocated more than 5,000 billion VND to invest in this project.
In particular, this is the largest cable-stayed bridge, the first "made in Vietnam" , from design, supervision, construction, including the most difficult item of cable tensioning, all done by Vietnamese engineers.
Traffic jam on My Thuan Bridge from Can Tho to Ho Chi Minh City on the 6th day of Tet 2023. After My Thuan 2 Bridge is built, this traffic jam will definitely disappear. Photo: Phan Tu
At the closing ceremony on October 14, 2023, standing on My Thuan 2 bridge, pointing towards My Thuan bridge, Prime Minister Pham Minh Chinh said: "Previously, for My Thuan bridge, we had to borrow foreign capital, design was also foreign, construction, supervision was also foreign and the construction time was also very long, more than 4 years.
Now we have state capital, mastered the technology, designed, constructed, and supervised ourselves, in just 3 years. Despite many difficulties, we have overcome them, reaching the finish line earlier than expected, connecting the two banks of Tien Giang - Vinh Long. This is a very commendable result."
Mr. Le Quoc Dung, Deputy Director in charge of Project Management Board 7, said that during the implementation process , the My Thuan 2 Bridge project has always received special attention from the Government, the Prime Minister, and leaders of the Ministry of Transport.
" Despite many difficulties during the construction process, we have made efforts to shorten the time in many items and still strictly control the technical factors and quality of the project.
The inauguration of My Thuan 2 Bridge one month ahead of schedule is the result of a long process of efforts by a team of engineers and workers working day and night on the construction site," Mr. Dung emphasized.
The two main spans of My Thuan 2 Bridge connect the two banks after 3 years of construction. Photo: Nguyen Ro Lil
Mr. Trinh Truong Hai, Director of the My Thuan 2 Bridge Project Management Board (PMU 7) said that My Thuan 2 Bridge has very difficult technical factors such as bored piles with a diameter of 2.5m and a depth of more than 100m. But these items has been mastered by Vietnamese contractors in technology and construction for many years.
Just casting the tower pillar is more than 120m high , a total of 33 tower segments and the main span beam is 350m long and 28m wide. With 128 cable-stayed bundles, this is the first time Vietnamese contractors have mastered the design, supervision, construction and confidently mastered the technology of constructing large-span cable-stayed bridges .
With the casting of a tower column over 120m high, a total of 33 tower segments and a main span beam 350m long and 28m wide with 128 cable-stayed bundles, this is the first time Vietnamese contractors have mastered the technology. Photo: Chi Hung
Mr. Phan Van Quan, Commander of Trung Nam E&C contractor at My Thuan 2 bridge project, is the person who participated in the construction of Tran Thi Ly cable-stayed bridge across Han River (Da Nang), inaugurated 10 years ago.
But at that time, this project also needed foreign contractors to construct the cable-stayed section. Vietnamese engineers worked and learned experience at the same time.
Mr. Quan analyzed: Cable-stayed bridges are designed with a thin, soft girder structure , anchored by cable-stayed bundles . That is, from the time of installation , moving the casting vehicle until the completion of a segment, there are always certain errors in displacement compared to theory, so it is necessary to calculate and update continuously .
In addition to the initial calculation, the construction process must have a deflection, so that when the project is completed, it will return to the correct height. But the reality is much more complicated because it depends a lot on the materials, the ambient temperature at each time of the day...
The cable-stayed cable tensioning stages are checked and parameters are continuously updated by Vietnamese engineers. Photo: Chi Hung
The cycle is when the casting car has been installed and adjusted , the cable is stretched for the first time, until pouring concrete with thousands of tons, the cable will stretch. After pouring concrete, the cable is stretched for the second time, the casting car is moved and then the cable is stretched for the third time .
In the above cycles, the beam segments will move continuously, sometimes up and down to more than 70cm compared to the design elevation . But it must be calculated so that after completing a cycle, the beam will return to the correct elevation that has been designed and calculated.
" Simply put, but in reality it is very complicated. The parameters to be calculated correctly also depend on many factors such as actual concrete strength compared to the initial calculation, steel hardness, steel density, environmental temperature... all of these factors affect the deformation of the beam segment.
Pouring concrete on a cool day will cause less expansion of the concrete. On sunny days, the concrete will expand more and the beam will sag more.
Casting each beam segment is a process of gradually eliminating previous errors, because the design theory cannot be completely correct with reality. Only when all beam segments are cast can it be called finished ," said Mr. Quan.
During the 3 years of project implementation, thousands of workers, engineers, and managers ate and slept at the construction site. There were times when the pandemic was raging outside, but the My Thuan 2 Bridge project remained closed to ensure progress. Photo: Chi Hung.
According to Mr. Quan, each cycle like that must update data to calculate the stiffness of the casting machine, of the beam at each time. The purpose is to predict the deflection of the beam for the next cycle...
Each casting must be calculated very carefully. The more detailed, accurate and fast the calculation, the shorter the time the construction team on site has to wait.
Until now, the calculation of cable-stayed bridges has been mainly done by foreign companies. They have a technical department abroad to do this calculation.
Domestically , they update the data, transfer it abroad, and after calculating, they transfer the data back for construction . The time to transfer data back and forth also takes quite a long time, while the construction team at the site has to wait, unable to control the progress .
With the My Thuan 2 Bridge project, Vietnamese contractors have affirmed their mastery of cable-stayed bridge construction technology. This is the premise to continue to affirm on other projects such as Rach Mieu 2, Dai Ngai Bridge... Photo: Nguyen Ro Lil
"All of these things are now calculated by a team of domestic engineers , working day and night at the construction site. As soon as the beams are cast, someone will go measure, enter data into the computer and calculate on the spot.
After entering the data in the afternoon, the team of engineers worked through the night to calculate so that the next morning they would have the parameters for the construction team at the construction site, without having to wait as long as before. Mastering the cable-stayed technology is there," said Mr. Quan, adding that after the first segment took a long time, the following segments were completed in less than 2 weeks, so the progress was mastered day by day.
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