One of the main challenges faced on this project was the 72 metre wide flyover, which has proven to be the most complex and largest bridge decks in the country. As the dimensions of the flyover continuously changed and the depth of the soffit changed from two metres to four metres consecutively, RMD Kwikform produced over 400 drawings for each one-metre section of the deck. Due to the complexities of the bridge profile and the changing deck soffit, it was crucial to utilise 3D design for the shutter system to ensure complete accuracy.
Using Tekfen’s computerised model of the interchange, the RMD Kwikform engineering team incorporated its formwork and shoring solutions to investigate the best solution to support the N5 flyover structure. Whilst taking into account the varying dimensions of the bridge deck, the engineering team also had to consider how the environmental issues would affect the design, such as the wind and the heat.
In addition to the support structures, RMD Kwikform utilised 3D modelling for clash detection, and to ensure the erection sequencing for each part of the shoring and formwork design, was as simple as possible. Finally, and the most critical element for both Tekfen and client ASHGHAL, was designing safe access and egress for the site team.
With equipment needs identified directly from the model, the logistics team used the RMD Kwikform local and regional branch network to ensure the high volume of equipment could be shipped to site ready for phase one of construction.
Recognising the shortage of skilled labour, and the potential need for a large amount of carpentry to achieve the required angles to support the bridge deck, Tekfen challenged RMD Kwikform to reduce the labour cost in the critical deck wing and inner wall sections.
Here, RMD Kwikform designed and fabricated hundreds of specially angled steel Superslim Soldier connectors. These connectors allowed the wing wall formwork to be mounted directly onto the Superslim Soldier primary beams, which were in turn supported by Rapidshor shoring. This arrangement gave the Tekfen team the ability to support the angled deck and eliminated the need for a large amount of carpentry, speeding up the overall erection process.
Due to the high loads on the deck sections and wing walls, Superslim Soldiers were also used as bracing supports, which fixed directly to the loading beams, all supported by the Rapidshor and Superslim Soldier primary deck support beams. For additional rigidity, a further two to three smaller bracing members were used in the formwork design, with a scaffold tube fixed to the formwork to support access and egress.
It was crucial that the Rapidshor steel shoring was erected correctly and safely, as this was used as the main support for the entire structure. Assembled in a birdcage arrangement, using its varying leg, jack and special tilt head attachments, the erection team were able to achieve the exact heights and angles to support the deck forms, without the need for packing.
With each erection sequence having to be broken down metre by metre, a permanent RMD Kwikform site support technician was on hand to work through the detailing with each team, checking the equipment assembly before each pour.
For Tekfen, all eyes in Qatar were on the safe delivery of the project, so overall confidence in the design solution was paramount as Ersin Cetinkaya construction manager for the project explained: “When we were tendering for this project, we looked around the market for a formwork supplier that could support the 3D design needs of the project. Having visited a number of RMD Kwikform sites and the engineering design team in Doha, we were confident in their technical and equipment capabilities, so we worked with the team to develop a phased construction programme.
“We also involved the client at key phases of the design, to explain our approach and show them the 3D model. This helped all of the technical experts involved in the project, as the model could be shared, commented on, and altered quickly by the RMD Kwikform team.
“To be able to see the project model before we even got to site meant that when we started the erection and equipment installation phase, we were not only able to show the site team the design, we were able to practically help them visualise where key elements would be situated. This in-turn led to a much smoother design to site delivery transition, especially as RMD Kwikform provided us with a permanent site support technician; this was a really asset to the project.
“With hundreds of operatives in our erection teams, the site support technician was able to ensure the competency of every individual, providing valuable training, whilst checking and signing off the formwork before the pouring sequences began.”
In total, the Tekfen team completed three concrete pours across the N5 interchange section of the bridge project. Equipment was then moved from this section of the project to support the sequencing of the remaining structures, all of which were completed in just six months.
Commenting on the project, RMD Kwikform Sales Manager, Izzet Ataol added: “As a business we have never provided solutions for a bridge like this in the whole of the Middle East. When our technical team saw the design, they likened it to that of a rollercoaster, as it moved so dramatically from one metre to the next, sloping in one direction and then another, with the concrete thickness increasing and decreasing across its profile.
“Having worked on many challenging projects before, we recognised the importance of our 3D modelling capabilities, not only for delivering a safe design, but for the practical benefits the system gives us. One such benefit was the ability to extract a complete inventory of the equipment Tekfen would need, not only for the N5 section, but the whole of the project sequencing, reducing the overall hire cost.”