RMD Kwikform supplies formwork for HK mega bridge
Systems used for construction of the turnaround facility have been designed by RMD Kwikform and provided to Dragages - China Harbour - VSL Joint Venture (DCV-JV).
The dual three-lane bridge is being constructed in phases and RMD Kwikform has previously supported major works for the land phase of the bridge, which will connect Hong Kong to China across the Pearl River. Once operational, the HKZMB will become one of the world’s longest bridges.
For the latest phase of the project, RMD Kwikform has supplied a range of formwork and shoring solutions, including its heavy-duty Megashor shoring to support the construction of the turnaround facilities in the water, over the marine viaducts.
The first main challenge was to design support structures for the placement of two precast segment on pier (SOP) base slabs. This was followed by formwork and shoring for two sets of cast-in-situ side and end walls, and top and wing slabs, with the structure completed using shoring mounted on steel beams to cast the final in-situ decks.
In order to form an elevated road across the existing new bridges, further support was required to place four precast girders, four precast I-beams and four precast corner beams. Once these main precast sections were installed, shoring solutions were designed to cast the elevated bridge decks and key connection segments to the main precast slabs.
Two sets of SOPs were required in total and each set needed to be complete simultaneously in just four months for this section of the project to stay on programme. RMD Kwikform worked with the DCV JV team to plan the construction sequence of the project, in line with the lift capacity of the barge crane.
Commenting on the construction sequence and the design of the formwork solution, RMD Kwikform deputy sales manager, Martin Chan, said: “The turnaround facility is located in the Western Waters of Hong Kong and spans over the top of the main dual three lane bridge. This meant the overall structure had to be built using both deck mounted and barge mounted cranes. In order to cope with the loads from the precast sections and the additional Hong Kong typhoon wind loads we designed solutions based on our modular Megashor heavy-duty shoring system.”
The turnaround facility has to be supported from the top of the cast in-situ pier. RMD Kwikform designed two identical Megashor tower arrangements, each side of the main bridge, reaching a height of just over 19m.
Each matching tower arrangement was pre-assembled in two blocks on a large barge and lifted into place, using its deck mounted crane. To complete the 19m height, two types of steel spreader beams were connected to the tower, which in-turn supported the main primary beams.
The bottom half of the tower, measuring 6.7m long by 6.3m wide by 7.7m high was made up of four sets of nine Megashor legs, connected together with steel SuperSlim soldiers and bar bracing. This base section was a fairly standard heavy-duty tower se-tup, supporting what was a much more complex second section comprising a main tower and Megashor raker frame arrangement.
Once the main support structure was in place, the precast SOP base slab was lowered onto the primary beams and stitched into the pier. The site team then used standard formwork, including Aluminium Alform beams, SuperSlim Soldiers and GTX beams to cast in-situ the SOP sidewall, end wall, top slab and wing slab.
By designing the overall solution and main towers to use as many standard components as possible, coupled with locally fabricated specials, the RMD Kwikform team was able to accelerate the design process with the DCV JV team, enabling erection of the equipment to start much sooner than for any alternative bespoke option.
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