By Katherine Weir21 December 2017
Large-scale construction projects can pose some unique challenges for contractors, making it harder for them to stay on top of safety, costs and the schedule when fighting against these issues. Excellent planning, careful equipment selection and a commitment to safety are crucial to building large structures, and can give a contractor a competitive advantage to finishing ahead of schedule and within budget.
International building engineers, Newtechnic, said that industry players and stakeholders were mistaken in the belief that new methods and technologies presented increased risk.
Andrew Watts, FIED, CEO of Newtechnic, said, “In fact, the opposite is true because by using technology it is possible to reduce risk while creating more imaginatively conceived buildings at lower cost that use less energy, are more durable, look better and are interesting to inhabit. They also take less time to make and, on completion, appear effortless.
“Some truly innovative buildings have been constructed in recent years, and cities are clamouring for more. In this time of huge opportunity, it is the responsibility of the construction industry to examine first principles and consider how today’s buildings, developers, designers and owners, may be judged a century from now.”
The company said this list of advantages had been proven in partnerships with developers, architects and engineers, where collaboration over data had revealed ‘absolute truths’ about buildings.
In this feature, we will look at several ambitious construction projects around the world.
Vienna, Austria – Austria Campus
Construction giant Liebherr is currently assisting developer Signa Holding with five modern, sustainable office complexes with ideal public transport links on the site of the former Vienna North railway station.
The Austria Campus project – which includes a hotel, a wide range of retail outlets, a conference centre, medical centre, kindergarten and canteen – has a gross floor area of around 303,000m2, and was said to be one of the largest construction works currently taking place in Austria.
Around 20 Liebherr EC-H and EC-B tower cranes are in action on the site to ensure smooth load handling, the manufacturer said. This urban development project in the Second Municipal District of Vienna is due for completion in 2018.
According to Liebherr, the 600,000m3 of material that has been excavated from the trenches is enough to fill around four million bathtubs, and the use of 20 Liebherr towers on the site ensures that around 24,000 tonnes of steel can be handled.
At peak periods, there are up to 2,200 construction workers on the Austria Campus site. With this volume of personnel, as well as several different contractors working at the same time, communication is vital for safety, efficiency and keeping to the development schedule.
Athens, Greece – Ptolemaida lignite power station
Height-access specialist Geda-Dechentreiter has deployed customised solutions for the construction of a new lignite block at the Ptolemaida power station located 600km northwest of Athens in Greece.
The new lignite block, part of the 660MW power station, will partially replace other power station blocks in Ptolemaida – some of which are up to 50 years old. The block is due to be connected to the grid in 2020.
To ensure the smooth transportation of employees and building materials, the Athens-based construction company Stagakis decided to install six hoist solutions from Geda.
Three Geda Multlift P12 Comfort devices were installed for the efficient transportation of people and materials, able to transport 1,200kg or 12 people quickly up and down. For the cooling tower of the new block, a PH 2032 650 Single personnel and material hoist was installed to assemble the external sheathing and to give workers access to the formworks.
A customised solution had to be developed for this part of the project as, due to the incline of the exterior wall, both the mast and the hoist itself had to be adapted to the changing geometry of the tower. An additional ‘D’ Door was used to exit the formworks.
The power pack, with its load capacity of 2,000kg or 25 people, was able to achieve a lifting height of 400m and a hoisting speed of up to 90m/min.
The last two hoists to be installed were two crane operator hoists – the Geda 2 PK – designed to transport two persons with a load capacity of 200kg. The hoists were installed at a customised height of 186m to meet the site requirements.
Pantelis Stagakis, the managing director of Stagakis, said, “We were faced with several complex tasks, in particular the height of the individual structures rising daily. This presented us with immense challenges, as the installation height of the cranes and the industrial hoist solutions also had to increase every day in line with the height of the building construction. It must also be possible to disassemble and reassemble the hoists at another location so as not to impede construction progress.”
Gothenburg, Sweden – Marieholm Tunnel
Germany-based formwork and scaffolding company Peri is currently working on an underwater tunnel that will connect the banks of the Göta älv river in Scandinavia. The 306m-long Marieholm Tunnel will ensure that the river can be crossed quickly using its six vehicle lanes.
The structure is being built in the form of an immersed tunnel. Three tunnel sections, each measuring more than 100m long, are being produced in a dry dock with the help of a Peri Variokit tunnel formwork carriage and will be submerged in a trench excavated on the riverbed.
Difficult ground conditions and the sensitive ecosystem of the Göta älv river have presented very challenging conditions during building operations, Peri said. The construction method has also brought its own challenges as the tunnel will be immersed.
The opening of the tunnel, designed for a service life of 120 years, is planned for 2020. To produce three tunnel segments, an 18m-deep dry dock was created on the banks of the river as a direct extension of the finished tunnel itself. After production of the individual tunnel segments has been completed, the dry dock will be flooded with water and the respective segment pulled out onto the surface of the river and then lowered to its position on the riverbed. The individual segments are subsequently connected with the joints tightly sealed.
Due to the length of the tunnel segments, the lowering procedure is a major task for the construction team.
Peri said that intensive and close cooperation between all parties was essential on this unusual tunnel project, from the initial planning idea through to the final delivery. Engineers from Peri were involved very early in the planning stages, working in collaboration with Züblin Scandinavia so that the idea could be developed into a cost-effective concept.
The solution created for the Marieholm Tunnel project was a mix of standard systems and project-specific formwork, ensuring efficient on-site operations. The advantage of the Variokit solution, Peri said, was its high degree of flexibility combined with a low weight, which meant that the slab formwork carriage was relatively light, weighing around 75 tonnes.
Morocco - Grand Théâtre de Rabat
An impressive project that Newtechnic has been involved in is the Grand Théâtre de Rabat in Morocco, envisioned by architect Zaha Hadid as part of the programme for cultural development in the region. Inspired by the Bouregreg River, the fluid design incorporates a 1,800 seat theatre, a 7,000-seat amphitheatre and a small experimental performance space.
The main envelope system for the theatre is based on opaque glass-fibre-reinforced concrete (GRC) rainscreen cladding, fixed to the primary structure – a mix of reinforced concrete and steel. The main drive for this method was to give a 60-year life span to the envelope system. The GRC panels, up to 4 by 2m in size, did not require the conventional steel backing frame to be cast-in underneath the panel.
For this project, Newtechnic undertook analysis and testing of several parts of the design, including Computational Fluid Dynamics (CFD) analysis for cladding pressures that was subsequently validated by an early-stage wind tunnel test. By analysing realistic wind loads, and stress and deflection of the panels on the unusual geometry of the building, the project could progress knowing that all scenarios had been considered.
Newtechnic said, “Structural calculations for each component were undertaken for each project-specific configuration by using finite element modelling and scripting to automate the structural analysis process for all panels.”
The design of the adjustable steel fixing bracket was conceived so that only one fixing type was used across the whole project, which would minimise cost, the company said.
St Petersburg, Russia – Lakhta Center
Once completed in late 2018, the Lakhta Center in St Petersburg, Russia, will have the accolade of the tallest building in Europe. This futuristic building complex, designed by Tony Kettle with a useable floor space of around 400,000m² across 87 storeys, will eventually rise to a height of 462m and incorporate a high-rise office building, a hotel, a science world for children, and sport and recreational areas.
Peri has been providing the contractor of the project with formwork solutions for the record-breaking foundations through to the complex shoring arrangements.
Planning work for the foundations proved to be extremely complicated, not only due to the height of the structure but also because of the difficult ground conditions, with the construction site being situated directly on the coast, said Peri. High wind loads also had to be taken into consideration.
The main challenge for the realisation of the high-rise building was the continuous, spiral-shaped rotation and the subsequent constantly changing slab areas.
The special requirements for the foundations could not be met with a massive bottom slab which meant that a project-specific special solution was developed – positioned on 264 piles that reached a depth of 82m. When concreting the foundations in March 2015, the construction site team set a new world record, entering the Guinness World Records as the biggest continuous concrete pour ever carried out.
The foundation work proved to be very complex and Peri application technology from Russia was used to develop the formwork solution for the foundation walls. The ACS self-climbing system was combined with Vario GT 24 girder wall formwork to realise the core. This meant that the formwork could be lifted quickly to the next casting segment each time without the use of a crane and regardless of the weather conditions, said Peri.
Due to the flexible design of the girder wall formwork, the construction team was able to continuously adjust the formwork to suit the changing building geometry.
Riyadh, Saudi Arabia - KAFD Metro Station
In Saudi Arabia, the futuristic design of the King Abdullah Financial District (KAFD) Metro Station was driven by the need to provide a weather-tight and thermally insulated envelope around a supporting structure, said Newtechnic.
The company said, “The geometry of the envelope is not driven by a structural primitive that seeks to provide structural efficiency, but by the requirements to enclose the interior space with the minimum amount of internally air-conditioned volume.
“Consequently, the zones for the depth of the facade and its supporting structure are required to be minimised to contribute to this concept. The goal is to minimise installation time through prefabrication while achieving a highly durable facade assembly.”
Striving to keep costs down, two independent elements fixed to a single threaded bar were used instead of casting, while spider fixing technology was chosen to ensure high levels of adjustment and flexibility.
Newtechnic conducted a series of early-stage iterative studies that introduced a slight double curvature in the perforated parts of the envelope, which were said to be subjected to larger deflections. This allowed a significant reduction in the size of the steel of the primary shell structure for these areas, the company said, without visibly altering the architectural content.
These studies were made possible by applying the results of a preliminary finite element (FE) analysis of the building to the structural model of typical areas of the facade.
Back to clever cost-cutting, Newtechnic avoided generating project-specific technology, instead using a set of current technologies to achieve the weather tightness of the building and coordinate economically with the supporting steel structure