Breathe easy in Oodi

The new library is being built according to modern construction requirements. Besides being built of wood, glass and steel, Oodi also follows strict building engineering standards to guarantee a comfortable visiting experience in terms of the air quality inside the building. The highest possible purity classification requirement has been set for the indoor air quality. Due to this fact, the builders are now working in clean and healthy indoor air and the library users will be able to visit a building with clean indoor air.

In the computational modelling, ventilation pipes are visible as thick and white. Altogether, 20% of the pipe installation work has been finished. The installation of the main pipelines for other building engineering works has continued at a faster pace as over 70% of their installation is now complete. HVAC planning has been carried out by Ramboll, and the contractor is Are.

“The strict purity classification P1 requires that no impurities are released in the air ventilation system during the construction phase and that the system complies with the highest indoor air quality requirements at the time of the transfer of the building. We are following these standards now, and it feels so clean that you could even set up a hospital in these library premises”, laughs Tony Lindholm, Are project manager responsible for building engineering. His computer screen displays ventilation pipes that were recently installed on the second floor.

Due to the purity classification requirements, the basement premises have been vacuumed and equipped with machines that absorb unclean air via High Efficiency Particulate Air filters. Mansoor Ardam, head of unit at YIT, examines the nozzle of the vacuum cleaner.

All machines are equipped with dust removing technology and overpressure and vacuum blowers. In operational tests the machines will be tested with a gel tape system, which will show any particles remaining on top of the gel. Mansoor Ardam presents one of the ventilation units.

Even the painters are working for better indoor air quality

A room cannot receive the status of purity classification P1 unless its surfaces are dust sealed. This job is carried out by the painter. Master Painter Pasi Kalliokoski from Lainisalo Rakennusmaalaus Oy has been working at the Oodi construction site since this summer.

“To achieve P1 classification, all rooms and shafts must be dust sealed. This is done using water-soluble paint or varnish. All products have the highest possible environmental classification, M1 and CE marking”, says Pasi as he marks a constructed wall that needs to be smoothed.

M1 means that the product has been tested in a neutral laboratory, and it does not release any chemical emissions into the indoor air. CE marking indicates conformity with EU directives.

Maalarimestari_Pasi_Kalliokoski2

Lately, Pasi’s tasks have included the spray-painting of the second floor ceiling black. Building engineering systems installed in the ceiling will be painted black at a later stage. The pipes are covered with paint as false ceilings will not be utilised. For the time being, Pasi works on his own. More painters will be needed as soon as new dividing walls have been erected. The contract includes all smoothing and painting work in the library.

The first facade elements have been installed

In September, the first facade elements were installed in the northern end of Oodi. Half a dozen elements at a time were transported by truck.

At this stage, the elements installed are the ones that will be covered with the final timber cladding. The current elements are readymade plates with a thickness of 280 mm, and they include thermal insulation and a vapour barrier. The steel constructions were equipped with mounts for the elements, so the plates were quick to install. Photo: Mansoor Ardam.

At a later stage, these elements will be covered with a timber framing, on top of which the final timber cladding will be put in place. Framing guarantees air flow under the wooden timber cladding and acts as reinforcement for the base. The facade elements are supplied by the Estonian company Timbeco Woodhouse OÜ. The same company is responsible for the production of the roof elements.

The thermal insulation of the facade with elements continues from north to east, i.e. towards the direction of Töölönlahdenkatu. After that, the works will continue at the southern end, which is now protected with plastic sheets. The last steps will be taken at the western end, in the direction of Kansalaistori Square, as this is the section through which all the building materials are brought into the building.

The idea behind the timetable – steady progress and smooth operatio

The scale, size and uniqueness of the new library make project management a challenging task. Every step and phase must follow on logically and smoothly from the last, even though unprecedented solutions are also needed sometimes.

The basis of the construction process lies in the carefully planned construction timetable, which ensures that the main contractor and the dozens of subcontractors work as planned.

“We manage the timetable with a system that is better known as Location-Based Management System, i.e. LBMS. In every separate area, all work stages are carried out one after the other, and the area is finished in one go”, says Mansoor Ardam. The YIT slogan has also been printed on the back of the workers’ shirts.

Besides the computer program, colourful Post-it notes are used, covering the walls of the negotiation room. They all summarise the progress week by week.

The idea of LBMS is to minimise all unnecessary waiting periods. For example, as the bricklayers finish their work in one sector, the painters will quickly follow and start their work. Each work group moves from one site to another within the construction site, and everyone works at the right place at the right time. Therefore, many work stages are in progress simultaneously, and the construction of the building progresses steadily.

 

Text and pictures: Liisa Joensuu/Tmi Magic Words

Massive roof element puzzle

The first roof elements have been erected in the northern end of Oodi. Piecing them together has been a giant jigsaw puzzle of rectangles and triangles, but it isn’t the lightest of jobs: the elements are 12 metres long and almost a metre thick. Their widths vary, but they all weigh thousands of kilos.

‘We’ve only been able to bring two or three elements at a time to the site. The largest of them weigh eight tonnes,’ says YIT’s senior site manager Tero Seppänen.

In late August and early September, a pink gypsum board was installed onto the elements, to function as fire retardant. The gypsum board will later be covered by the ceiling. At the same time, an architectural structure typical of the indoor area of the northern end, the balcony which can be seen in the background, was being built on the third floor.

Nostimet_ja_kipsilevynleikkausta

The roof elements were lowered into the supports waiting in the steel structures and screwed into their places. The Estonian Timbeco Woodhouse Oü was responsible for manufacturing the elements, and has now started installation work. The elements were cut to shape at the Timberpoint Oy factory in Loviisa.

The elements were prepared in detail: places were even prepared for the skylights, such as the octagonal recess in the picture. In the seaming phase, the long sides of the elements are filled with a special urethane foam, and the short sides with mineral wool. It must be ensured that the top part of the seam is not too tight, because the wooden structure of the roof must be able to breathe.

Separate drainage wells on the balcony

The balcony is now waiting for the surface work, i.e. the concrete casting and waterproofing, to start. After those are finished, the surface tiling and wooden upholstery can be put up.

In order to prevent the balcony from becoming slippery, electrically heated drainage wells are installed within the structure. They will not freeze in the winter, allowing water to run off the balcony quickly.

On the third floor of the library, preparations are being made for the installation of the glass facade panels. Support structures for them are being built in the northern end. YIT’s site manager Mansoor Ardam shows the supports behind the balcony, where the floor-to-ceiling glass panels are to be installed.

Casting the final part of the concrete floor on the southern end of the third floor in late August proved to be quite a task. The casting had to be done in one go, which took from 5 am to 8 pm. Over 200 cubic metres of concrete was used for the end part.

Floor casting is done on the second floor, but the fields of hollow-core slabs on the sitting area, which rise in steps, will be completed by stairs which will be cast in place. Concrete dust was vacuumed from the area from time to time.

Here, supports are being installed for the wall structures on the second floor, where the partitions will soon be built. Ceilings and floor surface materials will also soon be installed.

Final tightening of the anchoring cable

The work on the frame has now come so far that the anchoring cables running in the bull blocks of the steel arches which support the library could now be tightened for the third and final time.

This will bring the bridge arches to their full bearing capability. The picture shows the northern housing structure of the arches, along with its steel slabs.

The cables were tightened using a hydraulic jack, of which there are only two in all of Europe. One of these was borrowed in Finland for the use of E.M.Pekkinen Oy, who performed the tightening, for three days. After the tightening was done, the cables were cut off and the ends of the cable bunches plugged. Photo: Mansoor Ardam.

Site manager Mansoor Ardam wanted to find out how much the bull block moves during tightening. He placed two steel patches on the floor on either side of the seam. Using lines drawn, he noticed that the tightened slab had moved one centimetre compared to the untightened one. The expansion joints, which were previously left open on the first floor, can now be closed.

Floating movie theatre floor

Floor casting is a hot topic also in the first floor library movie theatre.

Due to acoustics, floating concrete slabs are used in the frame structure of the movie theatre. The yellow sound-absorbing Sylomer isolator separates the surface structure from the frame structure, preventing the sounds from the theatre from being conveyed to other parts of the building through the frame.

Interior materials on the drawing board

As the frame and floor castings are finished, the site can gradually turn its thoughts towards interior materials. Various brochures and samples on floor materials, for example, have gradually found their way to the construction site office.

According to Mansoor Ardam and Tero Seppänen, no decisions or agreements have been made yet, but preliminary discussions with various suppliers have taken place.

The interior materials will generate lots of discussion, with so many materials and colours to choose from. Practicality should meld with the visual values, and the overall look should please the public.

Summer’s still here, at least if you ask the hanging flower pot helmet. At the moment, approximately one hundred people are working with the construction of the library. The summer trainees were so good that YIT hired them as workers paid by the hour. As studying and work are combined, so too are theory and practice.

 

Text and pictures: Liisa Joensuu/Tmi Magic Words

Full speed on all floors

Construction of the Oodi library has continued throughout the holiday season all around the building; from basement to ceiling structures. Installation, piping, welding, casting, and inspection work is proceeding hidden behind the walls, but a huge milestone visible even from the outside has been reached: the frame of the balcony is now complete. The balcony will open from the west side of the building, offering a unique view of the most valuable core of Helsinki.

The final seams of the balcony were welded during the two last weeks of July. There are many things that still need to be completed, including the surface structure over the steel plate elements. When finished, the balcony will offer an unrivalled panoramic view towards Kiasma, the Parliament of Finland, Helsinki Music Centre, and Finlandia Hall. The tower of the National Museum can also be seen on the horizon. Who wouldn’t enjoy this?

Seen from below, the steel structures that support the balcony can almost be considered works of art. However, they won’t be visible later: just like the rest of the steel structures of the building, they will be hidden underneath wood panelling. The frame is now complete, and inspections of its structures are ongoing. The welded seams of the grids are studied one by one using ultrasound, just like in the steel arches that support the building. Once the frame has been approved, it’s time for the façade elements, whose installation is already being prepared for on the site.

The north end is ahead of the south

Plastic coverings have been drawn over the outer walls of the north sector, to protect it from the rain, because that is where the first wood panels will be installed. That is also where work on the inside will begin.

‘The north end is ahead of the rest of the building, but we are working all the time on the entire building. Floor work is proceeding as planned all around; the hollow-core slabs are in place, and more than half of the floor surface has been cast. We intentionally left a few seams open where the bridge structure will be further tightened’, says Mansoor Ardam, YIT’s site manager.

The unique nature of the overall project requires excellent planning in advance, strict monitoring, and keeping to schedules from the general contractor.

‘In a unique project like this, every stage has its special nature and everything takes its time. We must make sure everyone sticks to the schedule, because sometimes little things can stall the entire progress in a way that makes it difficult to catch up. Systematisation does not work here. We cannot operate like a car factory: this is by no means conveyor work’, Ardam explains.

The building engineering with its several pipe-laying projects has progressed up from the basement during the summer. The pipes are now at the second floor, where their supports were being welded to the ceiling in July. At the same time, the basement floor is seeing fire retardant treatment of ventilation equipment.

The building engineering is so abundant that its computer modelling makes you think of a bigger institution: a layman might take the view to represent a factory or a ship. The combined model using data from the various planners shows how and where the many technical systems, such as ventilation pipes, run between the different spaces. The large triangle in the middle represents the opening to be left between the floors. Glass railings are to be installed around it, allowing visitors to take a look at the lower floors from above.

The first interior walls are being built on the second floor, which will host studio facilities, a computer class, rentable work rooms, as well as office and negotiation facilities.

Some rooms will have dead partition walls and thorough soundproofing, while others will have glass walls. At the moment, the structures shown above the glass in the picture are being built.

Massive stairs coming up

Large, curved steel stairs will be installed in the middle of the building to bind the three floors together from the lobby. They will make an impressive element, which will also help people to navigate around the building.

The second floor will host a wide area with seats, which will rise upwards in small steps. The steel stairs will be located near this area, in the round opening. The grids and pillars of the building’s frame will be left partially visible, but with panelling.

A huge opening through the different floors is waiting for the 75-tonne stairs to be completed. The stairs are being made by Normek Oy, the company behind the steel arches that support the building. The installation of the stairs is expected to take place in December.

Attitude is everything, even in construction

Site manager Mansoor Ardam has his own philosophy regarding construction and the progress of the project. He quotes an Afghan saying, according to which the one with the brains of 40 ministers in his pocket is the one who will win the game.

‘The participants in any construction project must consider everything in advance, and commit to doing their best. Hindsight doesn’t help anyone. Everyone must be capable of making decisions, and matters shouldn’t be bounced from one person to the next. In construction, there is always someone who doesn’t mind something being left hanging. However, the site can’t wait. Not even a single screw can be left waiting for someone else to decide. The attitude is what counts; don’t do your best – do whatever it takes!

 

Text and pictures: Liisa Joensuu/Tmi Magic Words

 

Computer modelling images: structural engineering and HPAC planning by Ramboll, architectural planning ALA-arkkitehdit.

The residents’ living room awaits a roof

Following midsummer, the Oodi worksite is at a turning point, as both the roof structures and the works on the frame are almost ready. The first roof elements will arrive at the site during June.

“The steel frame of the building will be ready as planned by mid-July”, state YIT’s site manager Mansoor Ardam (left) and senior site manager Tero Seppänen. The construction site office screen behind them shows a live image of the entire Oodi site from above.

As the message on Kansalaistori says, Oodi will become the second living room to its visitors. For now, the rain still falls free on the living room floor, but one by one, the white steel structures on the third floor are being covered by a roof and surrounded by the glass facade panels.

“The roof is made of wood: it consists of laminated veneer lumber elements with a bitumen felt surface. The thermal insulation, for example, is built into the elements, which makes them almost one metre thick. The slightly curved shape of the roof is created during the installation of the elements, which are cut to shape at the factory”, Mansoor Ardam says.

The facade on the third floor is entirely made of glass. A model piece of glass represents the visual idea of the third floor: from the top, the glass is entirely white, turning clearer little by little towards the bottom. Or, as Ardam creatively explains, it has a solid cover of snow up high, with snow falling downwards, before finally the view clears. Perhaps the thought of snow in the middle of summer is what made the men so serious?

First, the roof must be made steady

A fair amount of jangling could be heard on the Oodi site around midsummer. The new soundscape comes from the tightening of the white steel structures of the roof.

During installation, the roof beams were left slightly loose, so as to give in when necessary during assembly. The joints were later tightened one bolt at a time. The installer, working from a manlift, used an impact wrench, which caused the clattering heard in the surrounding area.

Due to the work being done on the roof and balcony, lately the front of the building has been bustling with cranes and manlifts. The largest crane, the 300-tonne Havator tracked lattice boom crane, which runs on caterpillar tracks, will soon have finished its job. The blue-and-yellow Havator came to the site in January for the installation of the steel arches that support the building, and it has also been used for lifting the steel roof parts. The Havator will be dismantled in July.

A balcony, which will be open to all visitors, will be built on the west side of the library, towards Kansalaistori. The steel gratings to support the balcony were installed in the middle of the building in June. The beams rose lightly on the crane’s chains, but brawn was needed to guide them to a suitable angle to be attached.

At the moment, a whole jumble of support towers stand under the steel arches, supporting the casting moulds above them. The moulds and support towers can be removed once the horizontal concrete vault has been cast and has dried enough to support the structures. The concrete cast-on-site vaults will also play a part in supporting the steel arches.

The even floor is actually curved

Most of the floors of the library are made from hollow-core slabs and fields formed from them. The hollow-core slabs have been used in both public and residential buildings since the 1970s, as they are a fast way of creating large surfaces.

As the name suggests, hollow-core slabs are hollow, containing longitudinal cavities which make the slabs significantly lighter than solid slabs, even though they are made of reinforced concrete. The hollows can also be used for electric cables, for example. A pretensioned steel braid is running along the bottom of the slabs, which allows the slabs to be tensioned to increase their load bearing capacity.

“The tensioned cables make the slab curve a little. Even though the fields of hollow-core slabs look even, they are actually slightly curved”, Tero Seppänen explains.

Almost all of the hollow-core slabs are already in their places. The field of slabs that form the base of the upper floor also function as the ceiling for the lower floor. The seams of the individual hollow-core slabs are now being cast to make one big field.

The floors are already being cast in the north end of the building. Here, the floor of the ventilator room is being levelled after concrete casting. In addition to the basement floor, there are ventilator rooms on the 1M level.

Building engineering work in the basement has proceeded smoothly. 90 per cent of the work on the main pipelines is already done, and the installation of the ventilators is well underway. Various pipes will soon be led to the upper floors in shafts. ARE’s electrician Aarno Lehtinen (left) held a meeting with YIT’s site manager Janne Kurikka and site engineer Ville Nevala in the construction site office, because the installation of the cable trays is ongoing.

 

Text and pictures: Liisa Joensuu/Tmi Magic Words

From on-site training to master

Summer is here, bringing with it a number of construction students to Oodi worksite, there to gain valuable experience to support their university studies. Most students spend their first summer undergoing on-site training from the perspective of construction workers. More experienced students may also get to try their hand at supervision.

The summer employees at the Oodi site consider themselves lucky to be able to participate in such a notable project. The unique construction method offers plenty to learn, and experience from a historical site is sure to look good on one’s resume. Miika Ranta (on the left) and Anniina Kallioniemi (on the right) will eventually graduate as master builders from the Metropolia University of Applied Sciences, while Annukka Laurila (centre) is currently studying at Aalto University for a Master of Science (Technology) degree.

Although Miika Ranta is still young at 23, he already holds a vocational upper secondary qualification in construction, as well as plenty of experience in the construction industry. So far, he’s tried his hand at water damage restoration, sheet metal cladding, moulding, as well as window and fitting installation.

“At Oodi, I’m undergoing supervisor training, with my area of responsibility being interior fixed and operable glass walls. I’m getting to know quality requirements, measuring required quantities, as well as planning and scheduling construction work. Once the glass contractor arrives at the site, I’ll also get to supervise work for the first time. Over the summer, I’ll gain plenty of excellent experience to support my career as a master builder.”

A “minister of industry” in overalls

Annukka Laurila, 22, who is studying mechanical engineering and building technology at Aalto University, has a surprising dual role. While currently undergoing on-site training, she also works as Minister of Industry in the Guild of Mechanical Engineers.

“There are hundreds of students in the Guild of Mechanical Engineers, and I serve as the guild’s business relationship liaison. I procure funding and facilitate meetings between students and companies. I ended up here at the Oodi worksite after contacting YIT on guild business. They asked me if I had already found a summer job.”

“The Oodi site has a lot to give, seeing as how it’s unlike any other worksite. It’s cool to see how such large masses are being built on top of the arches and how the arches serve as buttresses. There’s a lot more to learn here than on smaller worksites.”

Continuing the family trade as master builder

Anniina Kallioniemi, 24, admits that she’s following in her family’s footsteps in becoming a master builder. Her father also works as a master builder, in addition to which there are a number of engineers and architects in her extended family. Although her father encouraged her to study and work in the same field, in the end, the decision to do so was Anniina’s own. Her fascination with the industry has continued to grow ever since.

“According to dad, I’ll make a great master builder because I’m good at maths, social and assertive. I originally thought about specialising in the humanities, and ended up studying to become an agrologist. I actually completed my Bachelor of Agriculture and Forestry degree a year ago. I’m also interested in horses, but decided to keep that as a hobby. I have a horse of my own, as well as a co-owned racehorse. I’m also into horse photography.”

“I’m thrilled to get to work at the Oodi site. We’re building something truly exceptional here at an incredible location!”

Steel frame on the third floor

The first two aboveground levels of the library will be clad in wood, while the third floor’s facade material is glass. In the early summer, the construction has proceeded to the third floor steel structures that will support the glass panels.

The glass-bearing white steel parts will remain visible even after construction is complete, while the grey beams and pillars on the lower floors will be hidden behind cladding. The white frame of the third floor is now slowly extending southward.

“The glass facade panels will most likely be manufactured in two different factories, since we need so many of them. The panels will have a printed surface, completely white on top and thinning towards the bottom. Currently we’re still in the design phase, after which we’ll proceed to commission the assembly,” says YIT’s senior site manager Tero Seppänen, whose artistic coffee cup was painted by his firstborn at day care a few years ago.

The support structures of the building’s load-bearing steel arches are now in the process of being dismantled, as all the welding work on the arches has been completed and the cast-in-situ slab supporting them has been tensioned. The removal of the supports will enable the installation of hollow-core slabs by the arches and the gradual extension of the third floor steel structures towards the south.

Numbers reveal what’s happening at the site

Site Office Manager Paula Antila views the construction of Oodi from a perspective of her own: through numbers. The majority of her working day is taken up by the processing of purchase invoices. They detail the materials arriving at the site as well as completed contract work.

“I check that the invoices are relevant to the project and have been drawn up according to agreements. I also verify that the goods have arrived, that we have a consignment note for them and that they have been signed for by supervisory staff. We share some of our tasks with the supervisory staff. Invoices are processed by others as well, and in accordance with our division of duties we register them to the budget, meaning the goal estimate. My duties also include posting the invoices to bookkeeping accounts and sending them on for approval.”

Every invoice is checked by up to ten people, so getting invalid invoices approved would be very difficult, even during the summer holiday season.

“Checking invoices is a multi-stage process at both YIT and the City organisation, and the regular professionals are never on holiday at the same time. I myself also have an experienced colleague who serves as my substitute when needed.”

In May, Paula reached a notable milestone on her career: 10 years of services at YIT.

 

Text and pictures: Liisa Joensuu/Tmi Magic Words

 

 

Nerves and blood vessels are born underground

If steel constructions form the skeleton of Oodi, building engineering represents its nerves and blood vessels. Now, capacities are being built to create electricity, heat, water and fresh air in the library. Technical systems originate underground, from the library basement.

The installation of building engineering is not carried out conventionally, as the possible movement of the frame of the building and, for example, the needs of the movie theatre and recording studio are taken into account during the installation process. In the basement, Are Talotekniikka Ltd employees, project manager Tony Lindholm (on the left), plumber Simo Järvelä (in the middle) and plumbing project manager Jani Lindvall, examine the installation map.

According to Lindholm and Lindvall, the possibility for the frame to move is rarely taken into consideration during installation of building engineering. In the Oodi building site, this possibility is linked to the indoors bridge that supports the building and requires flexibility for the structures. The solution is to install compensators in the pipelines to cushion the movement. Besides, several reference and dispatch points will be installed. These all suppress the noise and ventilation noise carried on in the pipelines.

“In this project, acoustics play a major part. The starting point is that the operations of the library are based on a soft soundscape. The noise reduction systems of the movie theatre and studio premises form a special challenge. Tailor-made sound attenuators will be installed in the movie theatre. These plans will be handed over to an acoustician, who will calculate the optimal octave bands and final decibels,” Tony Lindholm says.

Pipelines in clean spaces

One might think that the basement where the works are going on is cold, dark and dusty, but the basement of Oodi offers a surprise. Temporary heating is in operation, the lights are on and the premises are clean.

“This is a building site with purity class P1, which means that no dust particles are allowed in the air. Ventilators will arrive in a couple of weeks. They can’t get dirty already in the installation phase,” Tony Lindholm explains.

Several mechanical rooms will be built in the basement. The largest of these rooms will be as big as 100 square metres. In the mechanical room portrayed in the picture, the installation of the main pipeline is nearly finished. There are bushing sleeves in the walls for the future installation of pipelines. Eventually, the whole space will be filled with different types of machines and equipment.

The mechanical room will be fitted with the technology required by district heating and district cooling, and ventilation systems for heating and cooling, including heat recovery. The large pipeline in the middle of the picture is a ventilation duct.

The masonry work of the dividing walls and the main pipeline installations continue in different parts of the basement. The main pipelines form a network in the ceiling, as there can be as many as a dozen pipelines side by side. The liquid running in the pipeline is either water or glycol, depending on the purpose of usage – heating, cooling, drinking water or melting. The welder works on the branch of the pipeline which forms the coupling point to the radiators.

Plumber Simo Järvelä fitted grease trap hangers in the ceiling of a space that is below the kitchen of the restaurant. Institutional kitchens must be fitted with acid-proof sewers, as plastic pipes won’t cope with hot frying fats, among other things.

The skeleton grows above the ground

The supervisor in charge at YIT, Tero Seppänen, says that the construction of the frame of Oodi has progressed quickly. Over 65% of the steel structures have been installed. The frame should be nearly finished by the end of June.

“The frame requires a lot of work. We must think carefully about how to proceed. If there is some work that obstructs the works on the frame, we must reconsider the procedures and find alternative installation locations to keep up with the schedule. The skeleton will start to look like a building in the summer, when we start to install the roof and the wooden elements and glass structures in the facade.”

The welding works on the steel arches that support the building have been finished, and the inspection of the welds has also been carried out. Steel trusses have already been installed in between the arches as part of the massive truss structure of the frame. The cast-in-situ concrete plate that will be built in the upper part of the shaft in the picture will be stressed to support the steel arches sideways.

In the north end of the building, the installation of hollow core floor elements, i.e. the floors and ceilings between the different stories, has already started. In April, the work continued by the lobby, next to the movie theatre.

Trusses that support the balcony have been installed in the north end of the building. Trusses haven’t yet been installed in the middle of the building, as they would obstruct the cranes and the installation of the steel structures of the roof.

Aaro trained father during parental leave

Site engineer Topias Rintala has just returned to work from a “training period” of five months, i.e. parental leave. During the parental leave his one-year-old son Aaro taught him stress management, organisation and multitasking, among other things.

“With a small child you sometimes end up in tighter situations than at the workplace, especially now that the son has started to walk,” the father says.

Rintala moved to the library construction crew from a building site of a senior centre in Leppävaara. His tasks include supervising the timetable and costs. The training provided by Aaro became very useful, as it requires a swift reaction to jump into a moving train.

 

Text and pictures: Liisa Joensuu/Tmi Magic Words

Inside steel with an ultrasound

While cranes lift up heavy pillars and hollow-core slabs at the Oodi worksite, also light manual tools are needed for working on the details. Special attention has been paid to welded joints. In March, Suomen Testauspalvelu Oy began inspections of the welded joints of the steel arches that support the entire library. For this task, they needed a small ultrasound device, magnetic particles and a hand-held electromagnetic yoke.

“We started the inspections from the south and north ends of the arches. When a welded joint is inspected, it is complete. We make sure that no welding mistakes have occurred and that the welded joint has not cracked during cool-down. Even though welding is carried out inside a weather guard tent, it is possible that hydrogen may develop in the joint, especially during rain or in humid air conditions. This may cause a delayed crack”, said managing director Tarmo Tuomela while checking the screen of the ultrasound device.

These tests must be done very carefully, as the welded joints to be inspected with the ultrasound device are only two or three millimetres thick. There are so many of them that, together, they make up the whole thickness of the arch’s casing, 120 millimetres.

“The ultrasound device transmits the sound at the steel, using a selected angle. If the joint is faultless, the sound moves through the steel without any problems. Any defects reflect the sound back. Hand-welded joints quite often have small defects that reflect the sound back, and then we need to review whether the joint can be approved or whether it needs to be opened and rewelded”, Tarmo Tuomela says, explaining the basic idea behind the method.

In addition to the ultrasound inspections, magnetic particle inspection will be performed on the joints. First, Tarmo Tuomela will spray white paint as a contrast colour onto the surface of the steel casing’s welded surface. When the paint is dry, he will grab the spray bottle and cover the surface with some black magnetic particle powder. The idea of this method is that the magnetic particles will gather on the possible defect when the yoke (pictured) with positive and negative magnetic poles is held above the substance.

Weather guard tents are a clear sign of where welding work is taking place on the arches. Each arch has seven welding sites, which means that there are total of 14 places were joints are made. The weather guard tents of the end casings are not shown in the picture. The arch load is still resting on the support grids, at this point.

As an installation site, the Central Library is a medium-sized worksite for Suomen Testauspalvelu. Previously, the company performed the steel structure inspections for Kamppi shopping centre, for example, and it is also in charge of the inspections of the engineering works on REDI shopping centre’s steel parts.

“We carried out the first inspections of the library’s steel structures back at the Normek engineering works in Oulu. Our special competence is physical dimensional inspection, i.e. the control measurements of various parts. They establish whether steel pillars, for example, have been made correctly and whether their holes are in the right places. Even a small difference would multiply during the installation, causing major problems for the heavy structures”, says Tarmo Tuomela.

Pillars in place on the north side

The library will be built from the north side towards the south. For the general public, one of the most interesting points on the north side is the cinema, first of its kind in the history of Finnish libraries. In this computer model, the cinema is shown in red, as are the first steel pillars of the frame behind it.

The north end of the building, the space between the stairwell shafts and cinema, will house both premises for building services and office spaces. Installation of stair elements has been started in shaft number one, on the left. In shaft number two, the cast-in-situ works of staircase landings are in progress. The ends of the steel arches that support the building are shown in blue in the image.

The shape of the cinema and its ascending floor can be clearly seen in the image. The area has been covered with the first hollow-core slabs that will become the floors and ceilings of different floors.

Erection of the frame will start with the steel pillars. The vertical pillars will be joined by horizontal beams, and, gradually, the frame will become an enormous grid structure.

The root of a steel pillar is being prepared for installation next to the cinema, in the future foyer. The frame is being built one pillar and one beam at a time, like a jigsaw puzzle in a gigantic scale.

The western side of the completed building will feature a long balcony with a beautiful view towards Kansalaistori and the Parliament House. The balcony will also be built on steel grids. The southernmost of them was installed in March.

Each jigsaw puzzle piece and every installation costs money. These costs are monitored and budgeted for by site engineer Ville Nevala. He is studying civil engineering and construction economy at Aalto University.

“My thesis is almost finished. For my bachelor’s degree, my thesis subject was foundation and rock engineering, and my current thesis is related to planning management and scheduling.”

Nevala thinks that the Oodi worksite has stayed well within budget and on schedule. Nearing the spring, keeping to the schedule for frame works has required hiring some more resources.

 

Text and pictures: Liisa Joensuu/Tmi Magic Words

Highest quality all the way to welded joints

The quality of construction is constantly monitored in detail at the Oodi site. Everyday activities include operational and quality monitoring actions and recording the data from them. Everything is based on a quality monitoring plan, which site engineer Ahmed Ibrahim (in the picture) prepared for the central library as the thesis work for his Master’s degree.

‘Digital project management tools and mobile equipment make monitoring and documentation significantly simpler. All of the necessary data can be entered into the system directly on a tablet or phone, and it is available to everyone in real time,’ Ibrahim says.

The most eagerly awaited construction phase, which is the erection of the steel arches that support the entire library, is now ongoing on the site. Welding the parts together also requires precise quality control: the welded seams will be inspected using ultrasound equipment.

Ahmed Ibrahim says that software and cloud-based services are part of construction operations today. Production used to be managed by using files and files of papers, which were then transported from one person to the next, requiring pictures to be scanned and documents printed and sent by post.

‘These days, everyone uses the same software. We can document various observations and measurements, and attach pictures. One person inspects, another approves, and the designer signs everything. This allows us to build faster.’

Ahmed Ibrahim wrote his Master of Engineering thesis on ‘Leadership in quality assurance and creating the conditions – Helsinki Central Library project’. Based on the Finnish Congrid system, he developed a quality management matrix suitable to be used in other YIT sites as well.

Arches under the magnifying glass

As planned, the steel arches that support the library arrived at the site in 12 parts in February. Their erection could be started quickly, as the support structures were already in place.

The north ends of the steel arches were resting on the support grids before mid-February. Their bottom parts are protected by a weather guard tent, inside which they are connected to their housings.

‘The housings were made so well that we had no problems installing the ends of the arches. The bottoms have been welded inside the tents, because welding must be done safe from water, and the protective gases must stay within the welding area. For now, everything has gone well with the erection of the arches,’ says Pasi Parkkinen, Project Leader at Normek Oy.

The steel arches will end up supporting several structures, which means that the securing of the load-bearing capacity of the arches is being monitored particularly carefully. This means, for example, that the welded seams connecting the various parts are inspected dozens of times.

‘At first, the arches are only welded a little, so that the parts are connected, but the full weight of the arches rests on the support structures. One seam needs to be welded about 100 times before the arches are fully in place and the supports can be taken down,’ Parkkinen says.

Around ten people are working on the welding of the arches. Each seam is worked by two people at the same time. A third person is needed who is responsible for the pre-heating of the place to be welded and the additional materials, such as gas and welding wire. Pre-heating is important, because if the area being welded is too cold, the seam will crack.

The arches are welded on the inside, as well as on the outside. The welder has access to the arch housing through a hatch on the side. The piece of arch works like a chimney, letting all the fumes and gases out through its end. The housing is not only for small people: they are approximately two metres in width and height.

Ultrasound imaging for the welded seams

The use of ultrasound in the inspection of welded joints has become more and more common, and it is used on the Oodi site as well. The objective is to have intact seams, which can take the necessary load.

Structural engineers have appointed certain values to the seams, and an external certified institution, Suomen Testauspalvelu Oy, uses ultrasound to ensure the integrity of the seams and that their thickness corresponds to the defined values.

Shafts also support structures

Along with the steel arches, the lift and staircase shafts are also parts of the library’s supporting frame. The third shaft in the middle of the building supports even the steel arches.

The cast-in-situ slab, i.e. the floor, located on the third floor of the third shaft, is connected to the shaft, as well as the steel arches. The slab can be cast between the shaft and the arch structure once the steel arches are in place and the weldings are strong enough. The support grids for the arches are only removed after the cast-in-situ slab is finished.

The staircase landings are being prepared in the first shaft in the northern end. The first two large landings are cast in their places, and the smaller landing slabs are installed as elements. At the turn of March, the stairs themselves will arrive at the site as concrete elements, and their installation can begin.

Site engineer Unto Miettinen preparing coffee with his arm in a sling, and said that construction has already started on the fourth staircase shaft, and its first floor is already completed. The fifth shaft, which will be placed opposite the Sanoma House, is only begun once the steel arches are fully welded and the support structures, which currently block the way of the shaft, are removed. Miettinen pointed out that he isn’t wearing the sling due to an occupational injury, but that the problem lies in an older shoulder injury.

 

Text and pictures: Liisa Joensuu/Tmi Magic Words

A video on the construction of Oodi

See how the unique steel arcs of library Oodi are constructed on the video! The library is designed by ALA architects and built by YIT.

Watch the video here

More support structures for the arches

The installation plan of the most extraordinaire solution of the new library, the steel arches supporting the building, has been given more detail. Erection of this unique internal bridge requires a few more support structures, which means that the installation process has been delayed a little from the original schedule.

“The loads of the arch structure are very great. The original idea was that during the installation phase, the arches will be supported directly to the existing floor. However, more specific calculations proved that in addition to the vertical supports, the arch load should also be distributed with a horizontal grid that transfers the load to the footing structure. The horizontal grid will be introduced as a new solution,” says Tero Seppänen, YIT’s senior site manager.

During the installation phase, the arches will be supported with vertical and horizontal transmission grids. The horizontal grids required by the updated installation plan will be the first structures to arrive at the worksite before the arches, so the logistics plan was also updated. The support structures will not be removed until the arches have been welded into one structure and tensioned.

“The first grid delivery will arrive during the night at the turn of January and February, during week five, and the next during week six. The deliveries mean night shifts for the unloaders, as the loads will be delivered between midnight and four am. The first installations of the arches will begin sometime before mid-February,” says Tero Seppänen.

Finnish construction ethics dictate that safety is not to be compromised in order to make the work go faster, not even when the deadline is approaching. The change in the design proves how important it is to supervise how theory and practise come together and adapt the plans as the situation requires.

While the transverse support grids have been manufactured in Oulu at Normek Oy factories, the on-site workers have assembled a tracked lattice boom crane, Havator, for installing the arch structure. It was delivered in several pieces from Äänekoski, from the worksite of Metsä Group’s bio-product plant. The wide wheelbase of the tracks takes up a lot of space, and very large steel elements will be delivered to the site, which means that the worksite had to be extended further. Since the fence was moved in December, it has been moved again towards the west and the Parliament House. The arches will be transported to Helsinki in 12 separate pieces. Each delivery carries two pieces, so, in total, there will be six deliveries.

Lifting the arches requires detailed plans

When one part of an individual arch weighs more than 85,000 kilos, the process ahead will be a heavy jigsaw puzzle that requires careful preparations. In addition to the lifting and installation plans, detailed occupational safety plans are needed. All of this has kept YIT’s worksite manager and occupational safety manager Mansoor Ardam busy. He acts as YIT’s supervisor during the steel frame’s installation.

“Success is based on careful planning. The arches and grids are a challenge, but we will proceed in bits and pieces, one matter at a time and in accordance with the plans approved by the structural engineer. The work will be paused, if we notice a safety risk. It is important to react in time during the implementation phase, so that the support towers can hold, lifts succeed and everyone can go home safe and sound after the workday. Motivation is strong, and even if the project is complex, it does not have to be complicated.”

Mansoor Ardam has construction work in his blood. He says that his grandfather was a major contractor in the Afghan state. Mansoor came to Finland in 2005, and in 2012 he graduated as a civil engineer from the Häme University of Applied Sciences. Currently, he is studying for a degree in Master of Engineering in an Industrial Management degree programme in English. He will graduate in May.

“Large projects are already familiar to me. I’ve been in part of the construction projects of HKL’s metro depot in Roihuvuori and Otaniemi metro station. Both were successful, transferred over with zero errors.”

First shafts about to be completed

The construction of lift and stair shafts has progressed on schedule, and the cast-in-situ works of the three first shafts are almost complete. At the beginning of February, the work for the fourth shaft can be started.

The first shaft in the northern end of the building will be around 20 metres high. It reaches through the entire building, from the cellar level to the third floor. The eaves height of the building itself is 23 metres. Next to the shaft, part of the movie theatre wall and the shape of its space can already be seen. The actual building construction will also start from the north end: the first steel pillars and grids will be erected in February.

It is easy to watch the shafts being built, but a lot is also going on below the ground, for example, in the process of covering the concrete vault seen in front of shaft number three. Temporary heating was installed for the basement, as masonry works were started in the premises. During the masonry works of the basement’s partition walls, channels for ventilation and electric system pipes will also be made. ARE was selected as the building system contractor that will manage heating, water, ventilation, electricity and automation works.

When the lattice boom crane’s chains start to lift up the pieces of steel, they can also be seen from far outside the worksite. The crane will see some action as the winter starts to turn towards spring.

 

 

Text and pictures: Liisa Joensuu/Tmi Magic Words