CU1805

CASEstudy
Complementary construction
Complementary construction is rather a nice way to describe how all of the technologies and
processes involved in a major project can be integrated to work together - thanks to the
introduction of BIM
Complementary construction was
used to describe the development
of the Tripla construction project in
Finland, which features a busy railway
station with 50K+ passengers a day as
well as continuous railroad traffic. This
presented the developers of the project
with many challenges, which are being
overcome with software from Tekla that
leverages collaborative and open BIM
workflows, reducing the costs and
visualisation of the project while making it
easier to understand the end results.
Tripla in Central Pasila is one of Finland's
largest construction sites - actually five
construction sites put together. The gross
area of the site totals 350,000 m2, equaling
50 soccer fields, and more than 1,000
people are working on the site during the
most intensive construction phase. "In a
way, we have many separate construction
sites here: the parking, shopping centre,
station, apartments, office blocks, and
hotel. Although they are separate, all
Building Information Models use the same
coordinate system and are compatible,"
says Janne Salin, BIM Specialist at YIT
Construction Ltd. YIT is the general
contractor for Tripla.
Tripla is built in the middle of the city in a
challenging environment. The project is
carried out in and above a busy railroad
traffic area, which makes construction work
more challenging. A busy station area
demands high levels of safety: A worstcase
scenario would be a train accident
damaging the various structures. Building
on a working station also means that all
passengers need to be guided to a
temporary steel-structured station and
overpasses, and because of the train
traffic, some work has to be done at night.
The new railway station building is not
only a complementary construction, but
incorporates elements of the old Pasila
station building, which was not completely
demolished. YIT uses some of the old
frame in the construction and modification
work of the new station: the station
building was demolished to the level of the
existing station hall, and the structures of
the lower part were retained, reinforced
and repaired. The upper part of the station
hall is built entirely as a new building.
UTILISING BIM THROUGHOUT THE
PROJECT
For Tripla, all design work is done with
modeling tools. In the beginning of the
project, the base of the old station and the
excavated rock surface were laser
scanned. An inventory model was then
created based on these scans, providing
project members with comprehensive and
accurate initial information for design. The
initial building information model was also
used to check how the new structures
relate to the structures of the old station,
whilst the Tekla model enabled engineers
to check for things like additional
excavation or extra support structures.
The entire construction site has been
modeled, enabling the logistics
subcontractor to develop better plans for
their own work. The architect's IFC model
was utilised as the basis for the information
model - BIM data and the IFC file format
are used extensively on the Tripla
construction site, from initial design to the
virtual presentation of the end product.
As information flows smoothly from one
software application to another, models
can be combined and used to verify things
such as how various pipes, columns, and
beams fit together in the combined model.
In weekly meetings, the various project
parties use the combined model to check
how building technology and pipes crisscross
inside the building and where they
can find good paths for openings in the
frame. If they detect issues or structural or
technical clashes in the design,
modifications to the designs can be
agreed upon in the meeting.
The use of Tekla Model Sharing has
enhanced information transfer, as the
construction site can check the situation
in other Tekla Structures models, such as
in the shopping centre and parking
structural models. IFC models and
drawings always lag a little behind, but
Tekla Model Sharing enables checking the
real-time design situation.
The procurement organisation of Tripla
utilises BIM to easily calculate things like
the amount of building materials. BIM also
helps the allocation of requests for
quotations (RFQs) for different jobs.
16
May/June 2018