A suspended soffit system was used for the construction, with all of the main structural support above the quay.
The new quay is in the Åndalsnes region in Norway. Main contractor Kristiseter was tasked by the harbour operator, Molde & Romsdal Havn, to extend the existing quay to accommodate the increasing number of larger ships.
Kristiseter turned to Teknikkand RMD Kwikform to provide a solution to construct the new 17m by 17m pier, which will be connected with the existing structure by a 60m-long, 4m-wide footbridge. RMD Kwikform and Teknikk AS worked in cooperation to design an over slung support solution.
RMD Kwikform export sales and business development manager Martyn Henrysaid: “The new quay is a 17m by 17m insitu concrete structure, situated on eight steel piles, measuring 1.2m in diameter, and secured to the fjord bedrock 70m below water level. The quay is being cast in two stages, commencing with the concrete beams, and followed by the concrete deck.”
One of the challenges RMD Kwikform’s engineering team faced, was to provide a soffit support for approximately 780 tonnes of concrete, consisting of 1.2m-deep concrete beams, with a 0.7m-deep concrete slab above. However, due to the location of the concrete beams, situated at only 0.7m above the water level, the temporary works could only be support by the eight tubular steel piles, which formed the foundations for the entire quay.
After several concept designs, produced by RMD Kwikform’s UK engineering team, in collaboration with Teknikk, it was decided to use a hanging system for the formwork. The method uses a suspended soffit system with all of the core structural support above the quay.
The suspended soffit is supported by 180 hanger ties, which run from top to bottom of the structure and are secured to the formwork beneath the water level.
They consist of two layers of Superslim Soldier primary beams, one layer of timber secondary beams and plywood, all off which is fitted around the tubular steel piles. The hanger ties run through the entire concrete structure, and down to the lowest layer of beams in the soffit, beneath the water level.
Morten Hernes, project manager at Teknikk, said: “Kristiseter AS cast eight steel support posts into the top of each tubular steel pile. Each of these posts protrudes above the top of the core quay slab. Steel header beams then span between adjacent support posts; providing four additional support points at each corner of the quay.
“Two groups of 22m-long Rana beams span between the top of the header beams, and provide the support for five R700 truss modules, which in turn are 19m long and span at 90 degrees to the Rana beams. There are also wedge jacks situated between each Rana beam and R700 truss; this ensure the load can be easily released, without the need to undo all of the hangar ties.”
Guttorm Balstad, project manager at Kristeseter, said: “This has been a challenging project in many respects. Initially, we were looking into utilising a more traditional method to construct the quay, with the bearing structure designed with an underlying steel system and wedge jacks. However, this system did not provide us with enough space to carry out the works. Due to the headspace granted by the R700 beams, we have been able to utilise the concrete pump, and crane down material very easily. We have been very reliant on this system; otherwise we believe it would have been an impossible task.
“This is truly an ingeniously designed system. After contacting Teknikk and RMD Kwikform, we realised quite quickly that they had the solution we needed. What we have received from RMD Kwikform has been a good illustration of how things should be carried out on site, and how challenges should be solved. We are looking forward to future collaborations and will no longer hold back on taking on board new challenging projects.”