POTENTIAL IN THE MODEL-BASED DESIGN PROCESS
The initial thoughts on the optimum positioning of the main shafts and the equipment rooms were done in the project with 2D floor plan depictions, into which system symbols were inserted. In the clean room section on the second floor, which is a defining feature of the building, to avoid particle contamination in the semiconductor processing areas, laminar flow units were envisaged in recirculating air operation. With the choice of an energy and maintenance-efficient air supply system via pressure plenum from the technical area situated above, it was virtually possible to confirm the southern floor plan zoning from the competition design.
To supply the middle-inner laboratory zone, an additional walk-in shaft became necessary on all floors across the entire length of the rear laboratory walls. For regular maintenance of the more than 80 fire dampers there, the prescribed maintenance walkways were to be kept free as structural clearances.
This large central shaft made it necessary to widen the entire building by more than 3m. Already in pre-planning it was possible to take advantage of model-based design with BIM here to determine for development the required cubage of the shaft with all its crossing lines, which in the past, with conventional collision planning, was often only found out too late. “Build it twice” is what this construction work simulated with BIM is called, through which risk at the construction site is reduced.
Figure 2 depicts the design engineering for the ventilation ducts with the rough cubage and functional elements such as flaps and sound absorbers. With the 3D graphic, the depiction doesn’t suggest the sketchy impression of an approximate design any more. It includes the elements required to make a decision, based on which the project management asked for an increase of more than 6000 m³ to the cubic content (gross cubic space), even before the implementation costs were verified. The model-based implementation design of this section in the ventilation shaft (Figure 3) demonstrates impressively how the level of detail developed up to work phase 5.
Before completion of the implementation design for the initial trades, the planning stage reached was presented to the future users in a joint 3D workshop.
The consistent model quality permitted the conducting of various simulations by involved specialist planners through the IFC interface, even though some of these, such as structural dynamics experts and building physicists, were not involved in the data integration for the overall model. The high shock requirements on the structural dynamics, particularly for the clean room level, resulted in specific threshold definitions for the rigidity and inherent frequency of the construction. This could only be achieved using an in-situ concrete construction method with a high reinforcement percentage of the 30 cm thick concrete walls, with rigid slot and opening design. With the help of the 3D collision check, the positions of the openings could be coordinated early on in the route planning. Compared to the conventional planning process, changes to work could be made in the early phases.