Automation in Construction 11 Ž2002. 227–235 www.elsevier.comrlocaterautcon
Virtual construction of architecture using 3D CAD and simulation Mark J. Clayton a,) , Robert B. Warden a , Thomas W. Parker b a
Department of Architecture, Texas A & M UniÕersity-College Station, College Station, TX 77843-3137, USA b Brown Reynolds Watford Architects, Inc., College Station, TX, 77845, USA
Abstract 3D modeling and computer simulations provide new ways for architecture students to study the relationship between the design and construction of buildings. Digital media help to integrate and expand the content of courses in drafting, construction and design. This paper describes computer-based exercises that intensify the student’s experience of construction in several courses from sophomore to senior level. The courses integrate content from drafting and design communication, construction, CAD, and design. Several techniques are used to strengthen students’ awareness and ability in construction. These include:
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Virtual design–build projects in which students construct 3D CAD models that include all elements that are used in construction. Virtual office in which several students must collaborate under the supervision of a student acting as project architect to create a 3D CAD model and design development documents. Virtual sub-contracting in which each student builds a trade specific 3D CAD model of a building and all of the trade specific models must be combined into a single model. Construction simulations Ž4D CAD. in which students build 3D CAD models showing all components and then animate them to illustrate the assembly process. Cost estimating using spreadsheets.
These techniques are applied and reapplied at several points in the curriculum in both technical laboratory courses and design studios. This paper compares virtual construction methods to physical design–build projects and provides our pedagogical arguments for the use of digital media for understanding construction. q 2002 Elsevier Science B.V. All rights reserved. Keywords: CAD; Architecture; Construction
1. Introduction
) Corresponding author. Tel.: q1-979-845-2300; fax: q1-979862-2235. E-mail address:
[email protected] ŽM.J. Clayton..
It is often suggested that architecture students do not gain much practical knowledge of construction methods and management during their education.
0926-5805r02r$ - see front matter q 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 6 - 5 8 0 5 Ž 0 0 . 0 0 1 0 0 - X
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Although students typically complete courses in construction methods, many studio projects lack any semblance of cost or project management and may indicate only a rudimentary attention to construction. 3D modeling and computer simulations enable new pedagogical strategies that encourage architecture students to learn about the construction of buildings. Students may undertake AvirtualB construction projects as part of typical studio assignments. This paper describes computer-based exercises that intensify the students’ experience of construction in several courses from sophomore to senior level. The courses integrate content from drafting and design communication, construction, CAD, and design. Although the authors have not undertaken statistical analysis to evaluate the effectiveness of our teaching methods, our observations of the issues that have arisen in the courses and the behavior of students suggest that our teaching methods are achieving the goal of improving students’ knowledge of construction. In this paper we will first establish the need for improved construction education in architecture curricula in general by reference to industry trends. We will then describe related efforts to increase knowledge of construction content in both architecture programs and construction programs. Next, we will describe the exercises that we have developed to involve students in construction issues in foundation level courses. We will also describe exercises that we are using that are integrated into upper-level design studio courses. Finally, we will present some modest conclusions and describe plans for further work.
2. Construction in architectural education A growing trend in the building industry has been toward construction management and project management becoming independent services from architecture. While in the past, architects often participated closely in construction supervision and observation, more frequently in current practice architects have very reduced authority over construction. Architects often see this trend as a dilution of their
power and influence and consequently a reason for reason for reduced fees. Owners feel that architects frequently do not have the requisite construction expertise to contribute heavily in the construction phase of a project and consequently, an outside project manager is necessary w6x. As stated by Boone Powell, of Ford, Powell and Carson, AThe gradual but persistent erosion of the field has left architects with limited knowledge of building systemsB w1x. Practitioners sometimes lay blame for this trend upon schools of architecture for not providing sufficient technical education. Because faculty members tend to concentrate research and teaching upon aesthetics, theory and history, students may complete their education lacking know-how in building technology and construction w6x. Karloff w7x has also noted the frequency of the criticism that recent graduates lack knowledge of construction. However, he defends the schools by suggesting that their mandate is not to provide narrow, practical training but instead to cultivate skills in life-long learning. In his view, rather than relying upon the schools, practitioners should provide knowledge of construction to interns. Whatever the merits of one side or the other in the debate, it is clear that increasing students’ knowledge of construction is a desirable objective. In particular, knowledge of construction should be integrated into studio courses so that students’ gain an ability to apply the knowledge obtained in lecture and support courses. According to Adele Naude Santos, AOne of the Achilles’ heels of architecture education continues to be the lack of integration of technical subjects with design studios, despite the fact that this fusion is essential to architectural thinkingB w1x. Our approach has been to integrate construction into design education through computer methods that help to isolate construction issues and provide experience through simulation. An added benefit of using methods such as 3D graphics is that the visual modeling, rendering and animation exercises are fun.
3. Related work Two educational trends have provided a starting point for our course development, one from studio
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education and one from construction management education. So-called Adesign –buildB studios have been put into practice in many schools of architecture w2,5x. In these courses, students not only design a structure, but also construct it. Typically, the educational objectives focus upon cultivating teamwork and imparting knowledge of construction. Such a course can also impart a feeling of achievement and accomplishment to students that gives them confidence to act as professional designers. Typically, there is a real client for the structure, permitting students to gain some experience interpreting and negotiating with the client. Certainly design–build studios have a tangible and tactile quality that is distinctly different from conventional studios and appears effective in engaging students in construction issues. However, design–build studios also have disadvantages. They require devotion of large amounts of time and monetary resources to arrange for materials. The construction itself is often tedious or even hazardous. A single very small construction project may consume several semesters, sometimes resulting in the necessity to pass responsibilities off to several classes and groups of students in succession. The vagaries of weather or unreliable suppliers can introduce serious delays. These factors may impede the ability to Ascale upB a design–build course to reach all students in large educational programs. With over 400 students in a second year course in design and materials in our undergraduate program, the logistics of a design–build component are too overwhelming to serve as a standard teaching method and maintain on a consistent basis. The particular factors that are inherent to design–build courses may also limit them to a focus on small-scale architecture such as houses and recreational shelters. The field of construction management offers a possible alternative in recently explored techniques of using 3D CAD models to study construction issues. In the concept of A4D CADB, the 3D model is blended with construction schedule information to produce visual simulations of the construction process w4x. The effect is similar to time-lapse photography of a construction site. Research has established the effectiveness of 4D CAD in aiding construction managers in solving scheduling problems. One test compared paper-based 2D drawings, paper-based 3D
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CAD drawings, and 4D animated schedules w10x. The schedules created with 4D CAD were better in that they had earlier end dates, fewer activities on the critical path, smoother resource allocation, and longest float for activities. The effects were more pronounced for more complex problems and less pronounced for simple problems. Other research has used 4D CAD to communicate the reasoning behind particular construction sequences w8x. Our intention has been to test the viability of 3D computer modeling and 4D CAD as a way to enhance learning about construction among design students. Our working hypothesis is that virtual construction can increase construction knowledge among architecture students in ways similar to those achieved in physical design–build studios. There may also be advantages over physical design–build by using computer methods. We have prepared several exercises that have been fielded in a variety of classes. Further research will need to assess the effectiveness of our methods and identify more clearly the costs and benefits of these methods in comparison to other methods.
4. Virtual design–build One approach at circumventing the limitations of design–build while retaining a significant portion of the virtues is to exploit the computer’s ability to represent Areal worldB situations and provide a virtual design build environment. The process of building digital models of details and wall sections can be a close analogue to building an actual wall. A strategy in a sophomore course is to introduce students to common building materials by constructing their designs from virtual materials created using AutoCAD R14. Design projects are kept small and focused on particular materials and construction systems so that students can concentrate on issues such as roof–wall connections, wall–floor connections, openings in walls, wall–sky and wall–ground connections. Projects are typically 3 weeks in duration. Every brick, anchor bolt, wall tie, stud and joist is included in the model, with particular consideration of weatherproofing, structure, and finish materials. Each of these elements is represented in AutoCAD
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as 3D solids that are then collected into blocks. Students produce axonometric and perspective view of their designs, such as the one shown in Fig. 1.
5. Virtual office From past experiments we found that having each student develop his or her own building in the sophomore course prohibited explorations to the degree of detail that we felt they should experience. It is not enough to simply choose generic material types like wood, brick or steel. Students need to understand that the kind of wood, specific type and color of brick, and form of steel make huge differences in the quality and feel of the final building product. To allow for investigations at this depth, the current final exercise in the sophomore class treats the class as a single design team. Students fully develop a small building from schematics through design development in a team environment. This project builds upon their detailing skill acquired in the earlier exercises and introduces a simulation of professional teamwork in an office. The team project is usually 5 to 6 weeks long. The first week is devoted to a design charrette in which each individual develops and presents a solution. The class votes on a single solution to develop for the remaining time. The project is broken into components small enough to be handled by individuals or smaller teams of two. The large team is divided into smaller teams in the following way: 1. 2. 3. 4. 5. 6. 7.
Fig. 1. Exchange of a 3D model produced in Avirtual design-buildB showing the detailed assembly of a wall.
Plan and Elevation Site Exterior Walls Structure and Roof Vertical Circulation Toilets Program dependent spaces, such as entry, theatre, offices, lobbies, maintenance, etc.
The winner of the design charrette becomes the Aproject architectB responsible for coordinating all small project teams to unify design decisions. Each small team is responsible for developing its area down to the smallest detail. For example, the toilet team is responsible for all code issues, accessory choices, color, plumbing fixture choices, lighting, ceiling, and space planning. All equipment and finish choices are accompanied by manufacturers’ cutsheets and finish boards.
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Fig. 2. Example of a building design produced in a virtual office in which students worked as a team analogous to a professional architectural practice.
The final product for this project is a design development set of drawings that includes all 2D information, including building plans, sections, elevations, reflected ceiling plans, stairs and elevators.
Sheets of details derived from 3D solid models similar to the ones developed earlier in the course are also created. An example of a completed model is shown in Fig. 2.
Fig. 3. Example of 4D CAD animation produced by students.
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6. Virtual sub-contracting In another approach to the same course, students were divided into groups by building trade, such as foundations, rough framing, finish framing, roofing, plumbing, and electrical. Using a building that was designed in a professional office as the subject, each team developed a 3D model of the parts of the building pertaining to its trade. Using AutoCAD external references, the 3D models were brought together to portray a complete building. Just as with real construction, the importance of coordination and accuracy was a clear lesson, as students had to resolve differences between models created in each group. Improperly sized openings, badly placed plumbing, late delivery of trade models and other common coordination problems all arose in the exercise, A dimensional error in the professionally produced drawings was also discovered and had to be resolved among several trades. Once the individual models of the building components were gathered into a complete model, the students prepared construction schedules of their trade work and then collected all of the individual trade schedules into a master schedule. They then
used a custom software program called CSIM to associate start times and duration of construction to each AutoCAD entity w3x. CSIM was written by one of the authors using AutoLISP. Upon command, the software then hides all constructed elements and produces sequential images of the construction progress by making appropriate entities visible. The software generates individual frames of the sequence that portray change in state of the building as it is constructed, as shown in Fig. 3. The images were rendered with material mapping and shadows, saved to disk and then stitched into a digital animation using Adobe Premiere. The animation was put out to VHS videotape so students could share their work more widely.
7. Virtual construction in studio Similar techniques are applied again in studio courses at the third and fourth years. In one exercise in preparation for designing a large commercial building, the students explore archetypal construction systems. The objective is to help them learn about materials and assemblies and
Fig. 4. 3D rendered detail based on a design by Nicholas Grimshaw.
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the need to consider the integration of structure, mechanical and electrical systems. They employ the Building Systems Integration Handbook to study systems such as steel frame, cast-in-place concrete frame, and precast concrete frame w9x. Students create 3D models of all of the components of the archetypal wall section and develop a construction sequence. They can then use either AutoCAD with CSIM or 3D Studio Viz to produce animations to portray the assembly sequence. The process with 3D Studio Viz is as follows: 1. Import the AutoCAD model into 3D Studio Viz, making sure that settings convert each entity in AutoCAD to a separate entity in 3D Studio Viz. 2. Using the Track View window in 3D Studio Viz, add a visibility track to every entity. 3. Set the visibility of each entity to correspond to the scaled time of its construction. 4. Render the animation. With 3D Studio Viz, the camera can be moved during the course of the animation to focus upon particular elements being constructed. For example,
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while an exterior view is good for illustrating the construction of the roof, once the sheathing has been applied, the interior construction is hidden. With 3D Studio Viz, the color or degree of transparency of objects can also be varied to communicate that construction of a particular element is in progress. It is also easy to group multiple elements and manipulate them as a group. It is even possible to illustrate the movement of constructed elements and modules, such as how a wood stud wall is assemble in a horizontal position and then tilted up into place. As their designs progress, students use 3D modeling and construction simulation to further investigate critical details and assemblies. In recent projects for the Dupont Benedictus Competition, students studied precedents of innovative glass assemblies by architects such as Nicolas Grimshaw, Phillip Johnson, and Norman Foster. They illustrated the assemblies using 3D CAD and construction animations. An example is shown in Fig. 4. Students then adapted details for their own design objectives, producing designs such as the one shown in Fig. 5. As part of studio projects, students also developed cost estimates using techniques that were first introduced in an introductory computing course. Students
Fig. 5. Original student design for a glass detail.
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Fig. 6. Conceptual cost estimate produced by a student in studio design.
prepare a conceptual cost estimate based upon floor area, and an assemblies estimate for greater sensitivity to materials. Students are provided with spreadsheet templates and instructions for both kinds of estimate. They produce cost values as well as charts that analyze the totals and subtotals by category. The class shares cost figures to enhance the breadth of experience in cost analysis that students obtain. An example is shown in Fig. 6.
incorporating construction issues into studio courses. Informal observations of students who perform these exercises have led us to the following tentative conclusions. The exercise appear effective in enabling students to understand drafting conventions and the principles of parallel projections. The dynamic effect of switching a CAD view from plan to section to axonometric helps students to grasp the logic behind drawing conventions. The discipline of creating 3D that are precisely sized to match actual dimensions helps students to obtain an awareness of construction materials. The creation of 3D models of details drives home the issues of assembly and construction in a more powerful way than does conventional 2D drafting. v
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8. Conclusion Our experiments demonstrate the viability of 3D modeling and construction simulation as a method of
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The problem of building a collective 3D CAD model introduces students to the practical necessity of collaboration. Students become aware that a designer must coordinate his or her work with that of other participants in the design process. Collective projects with virtual construction can be at a larger scale than is possible in physical design–build studios, although they should still be fairly small. Construction animation graphically illustrates construction process, sequence, and issues of form work and temporary structures. It brings misconceptions to the forefront and drives home the lesson that architectural design must be constructible to be successful. It can grab students’ interest and make them aware of the construction aspects of architecture. Technical problems with using CAD in an educational environment still abound. A common problem is that students’ models become so large that computer performance is sluggish. Even though the storage capacity, memory capacity and processing speed of computers doubles and quadruples, student models always exceed the capacity of the available platforms. It has become clear to us that a particular challenge is to get students to build good computer models that are efficient and flexible rather than expedient ones that waste processing cycles. Virtual construction can be integrated into multiple courses to reinforce learning in a way that is unlikely from a singular design–build experience. In comparison to design–build studios, virtual construction can more easily reach more students in a wider variety of learning situations and wider variety of projects. The scale at which we have employed these methods Žover 1600 students in the last 4 years. would be impossible to maintain in a true design–build studio. Physical design–build studios nevertheless provide a valuable tactile experience that is not reproducible in virtual construction. We hope to collect empirical evidence regarding effectiveness of our methods in increasing knowledge of construction. Through surveys and standardized tests of construction knowledge, it should be v
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possible to detect trends and changes in student abilities. These methods are also a nascent approach to innovative construction documentation. A 3D model of a building, sequenced to illustrate construction and hyper-linked to specifications and product information, may be a very effective way of communicating to contractors and trades people. Teaching with 3D CAD can increase construction content in architectural education. Our use of virtual construction appears to be a viable way to respond to industry demands for increased knowledge of construction among architecture school graduates.
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