BIM’s evolution from pencil to computer
The evolution of building information modelling has resulted in new project delivery processes that are better aligned to current technological capabilities and changed market conditions, says TAHIR SHARIF, president of buildingSmart ME.
01 August 2011
BUILDING information modelling (BIM) is concerned with both technology and process, but in many ways the technological aspect has advanced at a greater pace and prominence than the methodological element to the extent that BIM is sometimes misconstrued as a technology in itself.
However, the effectiveness of any tool is dependent on the practices that govern its use. In the sphere of BIM, particularly, there is an onus to ensure that delivery methods are aligned with the unique project requirements and the particular functions of the tools deployed.
In this regard, it will be useful and interesting to trace the transformation of BIM from manual drafting to early computer-aided design (CAD) to object-oriented modelling and finally to BIM.
CAD was essentially a replication and part-automation of the manual drafting process – when a large percentage of construction documents and shop-drawings were plotted from computers rather than being manually drafted on drawing boards – and the evolution continued with the introduction of object-oriented CAD in the early 1990s. Data “objects” in these systems like doors, walls, windows and roofs stored non-graphical data about a building in a logical structure together with the building graphics. These systems often supported geometrical modelling of the building in three dimensions, thereby automating many of the laborious drafting tasks like laying out building section drawings and generating schedules.
A parallel development in the 1990s was the increasing use of the Internet for sharing data digitally. CAD files that had been exchanged on floppy disks within the design team appeared instead on Internet FTP sites, on web pages and as attachments to emails. Forward-thinking design firms who were adopting object-oriented CAD into their practices began sharing and delivering their documents to clients digitally and began investigating web-based project management and collaboration services.
But object-oriented CAD systems remain rooted to building graphics, built on graphics-based CAD foundations, and as a result were not fully optimised for creating and managing information about a building.
Other industries, such as manufacturing have realised greater benefit from non-graphical, parametric information technology tools. Another generation of software solutions designed with current technology was required to fully realise the benefits information technology can bring to the building industry. This next generation of information-centric software provides building information modelling in place of building graphic modelling.
BIM solutions create and operate on digital databases for collaboration, manage change throughout those databases so that a change to any part of the database is coordinated in all other parts, and capture and preserve information for reuse by additional industry-specific applications.
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Kirnu ... BIM structural model by SCAD. |
By storing and managing building information as databases, BIM solutions can capture, manage, and present data in ways that are appropriate for the building team member using that data. Because the information is stored as a database, changes in that data that so frequently occur during design can be logically propagated and managed by the software throughout the project life cycle.
BIM solutions aid the management of relationships between building components beyond the object-level information in object-oriented CAD solutions. This allows information about design intent to be captured in the design process.
The building information model contains not only a list of building components and locations but also the relationships that are intended between those objects: for example, that a door should be 1 m from a window or the eaves of the roof should overhang the exterior wall by 550 mm or that three beams should be spaced equally across a structural bay or that the slope of an excavation should be maintained at a certain angle. These relationships implicitly understood by the designer become explicit when the building is described in a building information modeller. The richness of the relationships embedded within building components themselves, as well as those embedded in the overall model, makes reuse of the data in other applications even more powerful and the design process significantly more efficient.
Indeed, we are now witnessing the emergence of new project delivery processes which are better aligned to current technological capabilities and changed market conditions.
Integrated project practices
A convergence of forces seems to be moving the architecture, engineering and construction (AEC) industry towards new forms of project delivery. This is reflected as fundamental changes within the building industry’s design and construction processes, including:
Collaboration: Technology, particularly BIM and web-based project management software, has created a solid platform for an improved, more efficient means of collaboration between all the parties involved in project delivery and is enabling the trend towards integrative digital collaborations characterised by strategic partners with shared outcomes, risks and gains.
Representation: Today’s means of project representation are moving from 2D drawings to digital models, where representation occurs simultaneously with analysis – changing the design process from representational (based on static, abstract representations of a design) to performative (based on desired outcomes).
Analysis: When design representations become performative, they enable rapid design inference – understanding the analytical ramifications of design decisions as they are being made – with analysis being performed by designers as an integral part of the design process. This approach is in stark contrast to more traditional “rule of thumb” evaluations of designs as they evolve.
Standards: As building codes are updated to consider building performance, there is an increasing obligation on designers to provide higher degrees of insight regarding building outcomes. In some instances, owners define technology standards to realise opportunities for increased project and data flexibility.
Fabrication: Digital fabrication techniques blur the distinction between design and production. As this occurs, design sensibility regarding constructability shifts, giving rise to extensive pre-fabrication, mass customisation, and factory-produced building components. Digitally fabricated building components further reduce the pressure on field construction productivity.
Architects, engineers and builders are responding to these changes by adopting new processes, forging collaborative partnerships, and utilising new technologies. This entails:
• Embracing internal change: Increasingly, AEC firms are transitioning to collaborative processes built on the use of digital models to inform and progress the project design and to aid construction. These processes are characterised by increased involvement of project planning, communication, and risk management in a comprehensive and open manner during design and construction.
• Creating collaborative partnerships: New partnerships (including proactive, timely owner engagement) that rely on collaborative digital models to facilitate decision-making are creating a new breed of construction/lifecycle-minded designers and design-minded builders who together are managing the project with process and outcome metrics – and putting increased emphasis on the consideration of value and cost.
• Leveraging new technologies: New tools and technologies are key enablers of the integration of design practice and construction. These include BIM design tools, 3D and 4D visualisation, model-based analysis, 4D modelling, fabrication from 3D models, model-based bills of materials and laser scanning.
Future of practice
What might be the impact of this method of project delivery on the practical, day-to-day business processes? Changes will occur in contracts and relationships, giving rise to new forms of standard contract documents that address importantly compensation, risk allocation, and intellectual property. There will be fundamental changes regarding professional standards of care and how the building process is regulated. Flexible project structures coupled with collaboration technology will facilitate the integration of global, extended project teams, increasing the overall flexibility of the building industry’s workforce. Traditional project phases will be adjusted and refined to accommodate an integrated project team and their project participation. As the building industry becomes more integrated, the education of future professionals will involve altered curricula that reflect the increasingly large footprint of building design and construction. The early success of using digital models to quickly iterate alternatives and understand their ramifications will spawn a new generation of analysis technologies that are deeply imbedded in design technologies.
IPD
The trends in delivery practices can be summarised in the concept of integrated project delivery (IPD). The American Institute of Architects (AIA) defines IPD as “a project delivery approach that integrates people, systems, business structures and practices into a process that collaboratively harnesses the talents and insights of all participants to optimize project results, increase value to the owner, reduce waste, and maximise efficiency through all phases of design, fabrication, and construction.”
According to the AIA’s Integrated Project Delivery: A Guide, the defining characteristics of IPD include:
• Highly collaborative processes that span building design, construction, and project handover;
• Leveraging the early contributions of individual expertise;
• Open information sharing amongst project stakeholders;
• Team success tied to project success, with shared risk and reward;
• Value-based decision making; and
• Full utilisation of enabling technological capabilities and support.
Case study
BIM software was used to model and manage the structural information throughout to create Finland’s pavilion for the Shanghai World Expo 2010.
Called Kirnu, or ‘Giant’s kettle’, which was designed by Finland-based JKMM, the pavilion won first prize in a design competition announced for the occasion. Due to the complex nature of the design and the requirement for swift erection and disassembly for future reuse, it was quickly recognised that the project would be largely managed through BIM. “From the day that Kirnu was chosen for the Finnish pavilion it was quite clear that there is a need for 3D steel design software,” said Jouni Lehtonen, construction manager for Finland at the World Expo 2010.
Shanghai Engineering Survey and Design (SCAD) created a BIM structural model used throughout the construction process of Kirnu. Lemcon China Company’s Shanghai office provided design coordination and supervised SCAD in the production of the BIM. Structural analyses were also performed on the model. Interoperability between the modelling and analysis software enabled bidirectional updates (between the two software) as the design was refined. When the final structural calculations were determined, the structural model was developed to detailed design level.
All of the construction elements would be made in such a way that the pavilion could be disassembled and re-assembled. Conceptual structural design by Finnish engineering office Aaro Kohonen Oy provided the idea of a space frame structure system for the pavilion. “Tens of thousands of bolt connections were needed in the building to enable easy disassembly after the expo. A challenging part in the project was to design and detail all these bolt connections accurately,” said Pekka Haanpaa, Lemcon’s design coordinator in China.
JKMM Architects used parametric software, referencing the structural model, to design the shingle cladding. The cladding surfaces were then referenced back to the structural model to ensure that the shape of the steel structure was designed correctly. These collaborative processes were critical in ensuring that each party had accurate and current information fully coordinated with other team members.
All steel parts and assemblies were named, numbered and specified according to the guidelines of design coordination. “Engineers checked out the complex connections by rotating the model and were able to accurately generate all steel shop-drawings from the structural model, thus saving in material costs and avoiding waste. It would have been impossible for engineers to convert this curved structure into 2D drawings by using just 2D software,” said Haanpaa.
The project team collaborated between Finland and China using web-based utilities. The process involved developing phased models for the different stages of the construction and reviewing these against snapshot images of construction as it progressed.
