Tracing the Development of Digital Architecture
By Kin Hui
Abstract
It was in the year of 1983. Coop Himmelblau, the architect from Vienna, started with planning the roof top remodeling at Falkstrasse. Its opening in 1988 marked the triumphal achievement of deconstructionists. The intersecting roof structure takes my mind to the cocoon that the protagonist resides in Metamorphosis, a novella written by the novelist Franz Kafka. In the same year of 1983, Zaha Hadid from Architectural Association in London, won in the competition for the Peak Leisure Club which was a proposal for the Peak in Hong Kong Island. It was highly regarded as a breakthrough of the visionary architect at the time. Their architectural language of complexity and fragmentation transported those young architects during 80s as the pioneers in the realm of digital architecture. The 90s heralded the age of CAD (Computer Aided Design). With its methodology and integrated approach, it facilitated the bourgeoning scene of high-tech architecture. Norman Foster was one of the vanguards for high-tech and is still an influential architect these days. For the last decade, it has witnessed a new chapter with building information modeling (BIM) being the tool for collaborative efforts in the Architectural, Engineering and Construction (AEC) Industry. The development of desktop softwares, eg Revit and Archicad, has popularized the use of BIM in new project development. I will take this opportunity to examine in this paper the digital phenomenon and to explore how CAD paved the way for BIM, and the future for BIM and heritage conservation.
INTRODUCTION
Within the last decade, a key development has been taking shape in the name of BIM. Instead of being a technology, BIM is commonly referred as a process which involves collaboration among stakeholders in a project. In AEC industry, the stakeholders can be broadly divided into the clients, professional designers/ specialists, and the contractors. They share a common data base which consists of graphical and non-graphical data documentation. It endeavors to achieve life cycle management for the buildings which are valued as assets.
For communication purpose, a 3D computational model will be developed which are exported to common file type, such as IFC file, COBie file, etc. Stakeholders work on the smart model which carries parametric entities which are modifiable. For example, the parametric components can be dimensions, materials or quantities, etc. The two dimensional (2D) drawings include the plan, elevation and section are all derived from the 3D parent model. This has the advantage that the 2D drawings can be fully coordinated with the 3D model. It can help to minimize any mismatch and error by integrating the 2D drawings with the unified 3D model. From the 3D model, one can generate spreadsheets of any specific data embedded into model.
The main objective of BIM is interoperability. Different professionals involved in the project can access and add information according to his role in the project. In Fig. 2, it illustrates the documentation for BIM within a framework of nine squares. For sub-system, it includes academia, companies and clients. At super-system, it has international standards, professional bodies and the governments. The nine squares allure to the ancient model of city planning as laid down in Hau Kung Kei (考工記), a classical work on science and technology of the Ancient China.
BIM MATURITY LEVEL
Fig. 3 illustrates the progression from level 0 to 3 for BIM maturity according to levels of collaboration among stakeholders.
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BIM Level 0 (Low Collaboration)
At this level, there is practically no level of cooperation. CAD drawings are used but the information of the model is not shared.
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BIM Level 1 (Partial Collaboration)
A common data environment (CDE) is used at this level. It depicts the transition from CAD information to 2D and 3D. It is noted that the generated models not being distributed among stakeholders.
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BIM Level 2 (full collaboration)
Collaborative working takes the centre stage, though the team members may not operate on the same 3D model. At this stage two new concepts are introduced, ie 4D, Time management and 5D, calculation of budget. International standard PAS1192 provides guidelines on how to attain BIM Level 2. To reach this level, 3D models are to be exported to common file types, such as IFC file, COBie file, etc.
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BIM Level 3 (full integration)
This is the final goal of the AEC industry. It represents the full integration of data and model in a cloud based environment. The project team can verify in real time the effects on the model by a single action. 6D concept is introduced with the building being managed in lifecycle from design to construction and maintenance.
BIM AND HERITAGE CONSERVATION
Fig. 4, one can also view conservation as an ongoing process involving the conservator, the contractor and the client. The interaction among the three parties provides the information exchange that in turn affects the outcome of work. It functions in a life cycle as opposed to the linear configuration. Therefore, one should constantly revisit different stages throughout the course of conservation work.
A heritage building to be conserved will normally go through phases, including gather of geometrical data and dimensions, research on architectural language and material, assess façade degradation and structural damage, collect data including computational simulation and infra-red thermograph analysis, and finally propose intervention.
Procurement method in the stage of building survey for built heritage will be crucial in determine the level of integration and how BIM can be brought into the conservation work. On the most basic level, site measurement by tape and dummy levels, then production of 2D drawings by hand or CAD with communication via paper print. For the intermediate level, site data is collected with the use of ‘Total Station’ device. Drawings are subsequently produced in 2D or 3D in CAD for communication among parties. At the most advanced level, terrestrial laser scanner (TLS) is to be procured to generate point cloud of the built heritage. Sometimes, TLS will be supplemented with Digital Photogrammetry and the technology of Structure from Motion (SfM). The point cloud is then transferred into parametric 3D model environment in common file types, eg IFC file, for inter-communication within in the team.
Case Study 1 – Century Tower, Tokyo
Pictures for Century Tower are presented in Appendix A. Norman Foster is the lead architect with Ove Arup as the engineer. The construction of tower is completed in 1991. The project team was basically the same team which worked on the Hong Kong Shanghai Bank Headquarter previously. It had the objective on rethinking the skyscraper in the realm of emerging high-tech architecture with a critical approach to existing rules and regulations. The client is Obayashi Corp. (大林組), one of the largest construction companies in Japan. According to Norman Foster, the project was significant in combining lasting values from both the East and West. The distinctive structural solution evoked certain characteristics of traditional Japanese architecture [1]. This project is a good early example on how high-tech architects took advantage of CAD and computational analysis to implement their design. It paved the stepping stone for BIM in decades later. To resist earthquake load, the eccentrically braced frame (EBF) was adopted which, combined with strong connections, the structure frame would flex with seismic movement. In Fig. 5, the drawing illustrates how the EBF deformed in reaction to seismic loading. This concept of flexing is identified with traditional timber pagodas in Japan which we will explore in further detail later in this report. Fig. 6 shows the computational analysis of steel joint under seismic loading. Ove Arup first started with using existing software but it didn’t cover the non-linear earthquake scenario. Therefore, Ove Arup had to develop software specifically in the structural analysis for Century Tower. The design engineer borrowed from their advanced technology group which was working on structural stability of nuclear waste containers. With this kind of research, accurate seismic analyses for building could be obtained. It has to note that every component in the building was pre-ordered in according to the way of Japanese system of construction management. A vast amount of effort was spent initially in drawing up and agreeing contract documents in incredible detail. Once after the initial long lead-in time, the physical construction on site was very smooth and fast.
Case Study 2 – Yokohama Pier Port Terminal
Pictures for Yokohama Pier Port Terminal are presented in Appendix B. Foreign Architects Office led by two young and virtually unknown architects, Moussavi and Zaera-Polo – taught in Architectural Association of London. They won the open competition in 1995 for Yokohama Pier. The project was completed in 2002. The design featured a fluid architectural space and was regarded as landmark achievement in harnessing 3D computational modeling from experimentation to realization for such a large scale project. Fig. 7 above shows diagram for circulation pattern of the cruise terminal that one can identify it as allusion to parametric modelling. The whole scheme eliminated any vertical column or architectural element in the form of vertical post. Circulation across different levels was channeled via ramp in lieu of staircase. It bridged the gap between infrastructure and architecture. In short, one will coin the phrase ‘infrastructure as architecture as landscape’ [2]. With the use of computational modeling, it demonstrated effectively that an architectural scheme of high degree in complexity could be realized within a short timeframe. The circulation for the project envisaged as continuous looped diagram. Visitors will meander both vertically and horizontally before arriving at a destination. The undulating contour of the building underlines an element of random freeness. It reminds one of the woodblock print of Hokusai (葛飾北齋) for the great wave or an album cover by the band ‘Joy Division’ – the Unknown Pleasures.
Case Study 3 – Conservation for East Pagoda of Yakushiji (藥師寺), Nara
The East Pagoda was completed in 730 AD during the Nara period. It is now the only original 8th century structure at Yakushiji. Due to the ground settlement at the central pillar or Shinbashira (心柱), the structure of pagoda was disassembled in 2012 for repair. The restoration was completed and the pagoda was re-opened to visitors again in 2021. Inherited from the Tang Dynasty of ancient China, five stories pagoda is a salient feature for wooden pagoda in Japan. To understand the structural behaviour, I have included the study of a typical five stories pagoda in Fig. 8. A timber model of the pagoda was made with attachment of electronic transceptors. The physical model was then subjected to simulation test for seismic movement. The transceptors would then send the signals to a computational model, and transmitted the pattern of movement of the physical model into the virtual model. In this way, one could understand how the pagoda would response to the earthquake. It was interesting to note that each storey in the pagoda jiggled independently like snake dance to dissipate the seismic movement. The traditional bracket system would slide to give flexibility to the pagoda structure. This explained why the traditional timber pagoda would be able to withstand the test of earthquake without fallen apart.
In appendix C, I have collected pictures of the top part finial of pagoda during restoration process. The part was called water flame or suien (水煙). The original copper suien was badly corroded and needed for replacement. BIM technology was procured in the restoration work. The original damaged suien was first laser scanned. Then the computational model was touched up, and restored virtually by artists in the computer. After touching up, it was 3D printed into a physical model. Sand cast technique was used to make the mould for bronze casting. By referring to photo of the original, artist finally gave patina to the reproduction to match the original suien.
FUTURE OF BIM AND HERITAGE CONSERVATION
For full integration of BIM into heritage conservation, one important aspect need to point out is the Geographical Information System (GIS). GIS is a digital map with connection to descriptive information. We can generate spread sheets on specific geographic data via GIS. For example, one may need to assess climate change and its impact on heritage monuments near coastal areas. In this case, the concern with whether would there be any risk of submergence into sea or damage by flooding will prompt for the use of GIS data. By geo-referencing 3D model of built heritage into GIS, we can tap into a greater world of geographic data that will be valuable to the future works of conservation.
It is worth to point out post-processing of point cloud is a subject that needs to be resolved. Currently, point clouds are to be manually clean up with the use of application like Cloud Compare. It is a very time-consuming task which is not particularly straightforward and may require one to have knowledge on photogrammetry. New attempt is made to allow for automation of importing point cloud. But it is still a novel idea that takes time for the technology in relating field to attain maturity. Besides, a small point cloud will be talking in the range of 3GB to 5GB in file size which a conservator will encounter great difficulty to maneuver in desktop computer. Therefore, to popularize the use BIM in heritage conservation, the obstacles in handling of point clouds have to be overcome first.
We foresee in the near future there will be more built heritage of 19th and 20th centuries being fallen into the ambit of conservators. They could be monument that involves huge quantities of repetitive components for which BIM will be come in great handy. For example, the Lloyd’s Building in London designed by the late Sir Richard Roger has become listed in the recent years. It is very sure that there will be more buildings in the similar category of significant and outstanding piece of contemporary architecture. Therefore, it is very definite BIM will gain ground in the field of heritage conservation in the future.
CONCLUSION
From the observation in this report above, we can realize that BIM has great potential to become a useful process for application in heritage conservation. But at the current situation, it is common for practice to use BIM in the development of new buildings. Owing to considerable amount of manpower to be invested in setting up 3D model for BIM, we can say lesser degree of BIM application for existing buildings or alteration and addition works. In all, the technology of BIM still need time to mature for gaining its widespread application in the field of heritage.
Lastly, it is worth to note the oral teaching/ kuden (口伝) in Japanese carpentry. A number of instructions deal with mental and emotional aspects of work. Whatever a person is involved in making, it is essential to grasp the underlying meaning and purpose [3]. Fig. 9 depicts slides taken from a talk by Norman Foster delivered in the opening of Century Tower. The juxtaposition of computer chip and the Zen garden brought the contrast of old and the new. But the essence was to question the cultural, technological and spiritual implication. If function is about keeping the rain at bay and the energy flowing around a building, then it surely is also about the spirit; the ‘Zen’ of the project if you wish to call it that [4].
Appendix
A. David Jenkins, Norman Foster Works 3 (P.331, Prestel, London, 2007)
B. Ferre. Albert, The Yokohoma Project: Foreign Office Architects (Actar D Inc., 2003)
