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BIM and Concrete Formwork: The Paradigm Shift in Formwork Industry

This article proposes an intriguing method for automated construction layout of concrete formwork systems using Building Information Modeling (BIM). Drafting and prepa-

ration of layout for formwork is one of the highly complex and perplexing tasks in construction since it encompasses the detailed characteristics of building envelope along with the associated structural members. Unlike structural drawings, drawings of formwork systems and its layout are done with more precision and revised in greater detail because formwork systems are temporary structures and lot of factors such as storage, transportation, assembly or erection and re-use, etc., are associated with it. These considerations will syllogistically influence the overall profitability of the formwork industry. Ad-ditionally, besides the inadequate design and inefficient formwork selections, the layout of the formwork systems have huge im-pact on the actual site characteristics so the factors such as the building shape, the type of labour used, alignment of the formwork and construction sequence of the formwork are to be considered in greater detail. However, these factors could not be accounted on the regular 2D Computer-Aided Design and Drafting (CADD), thus the sophisticated 3D CADD is preferred. Though the 3D CADD is efficient in providing an optimum solu-tion it is not impartable, that is the changes made on 3D CADD could not be altered easily so as to coordinate with the other construction personnel involved in the project. Thus, Building Information Modeling (BIM), an innovative technique is adopted in order to overcome these shortcomings. The BIM enables the acquisition of more precise information on the actual site char-acteristics than the 3D CADD and thus reduces the complexity of the formwork construction and enhance parametric change of formwork systems and the components to achieve optimum formwork design and construction sequence. To have a com-plete analogy of the importance BIM on concrete formwork systems, a firm research on the applicability and adaptability of BIM on the layout of concrete formwork system for G+20 high-rise building by AutodeskTM Revit® was carried out.

Formwork is a temporary structure that supports its own weight and that of the freshly placed concrete as well as the construction live loads. The layout of the concrete formwork systems is the most important factor to be considered in the formwork construction in addition to the design and selec-tion of the formwork systems. The layout of formwork is the most influencing factors in determining the shape of the fin-ished structure, thus a greater degree of precision is con-sidered in the drafting of the layout systems. Generally, the 2D Computer-Aided Design and Drafting (CADD) is used for drafting the layout of the formwork systems.

These 2D CADD software such as AutodeskTM AutoCAD®, Bricscad for commonly used for the complex layout of the

concrete formwork systems in heavy constructions. In these software, the formwork components and its associated ac-cessories are drawn first and then connected to form the finished formwork systems. However this is time-consuming, thus in most of the construction companies, they use pre-drawn CAD elements known as Blocks to draw the commonly used formwork systems.

Sometimes custom made programs such as ELPOS by PERI GmbH, for CAD by MEC CAD and Tipos 7.0 by Doka GmbH were developed and used as separate software or as an add-ins for the 2D CADD software so as to reduce the amount of time and complexity in drafting the layout of form-work systems. Moreover these 2D CADD software could not incorporate the site characteristics such as the building shape (for example, elevations), alignment of the formwork systems and construction sequence of formwork, which are the detrimental factors in formwork construction. Later, 3D CADD was developed to reduce the complexity of the formwork layout. Additionally, custom-made software was developed for the complex projects or specialty construc-tion. Though these 3D CADD is efficient in overcoming the shortcomings of the 2D CADD, it could not account for the parametric change characteristics required for imparting and coordination of the layout of formwork systems among the other construction site personnel.

Thus a rationalization of formwork layout incorporating the actual site characteristics and imparting the parametric change during construction is necessitated. This could be well achieved by an intriguing technique known as the Building Information Modeling (BIM).

Building Information Modeling

BIM is a reliable digital representation of the building available for design decision making, high-quality construc-tion documentation, construction planning, performance predictions and cost estimates. AutodeskTM Revit® is one of the most important leading BIM package and is used for this study. Revit means “Revise Instantly”. It is a powerful parametric change engine that it coordinates changes very effectively.

CAD vs 3D BIM Model

A 3D Computer Aided Design and Drafting (CADD) model includes geometric representation of the building whereas BIM is organized as a prototype of the building, in terms of building components and a wide array of information associ-ated with each of these elements. BIM model includes infor-mation used by other building analysis applications, such as cost estimating, energy simulation, day lighting and building

M.Ramesh Kannan & M.Helen SanthiDivision of Structural Engineering, School of Mechanical & Building Sciences, VIT Chennai

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code checking. The 3D models alone do not qualify as BIM models since a 3D geometric representation is only part of the BIM concept but it has to coordinate change that is it has to be parametrically adjustable.

The importance of the 3D BIM over the CAD diagram is well illustrated in the following. For the purpose of under-standing, let us consider a wall panel. First, the wall panel is drafted in 2D using AutodeskTM AutoCAD®.

Bim and Concrete Formwork Systems

The 2D drafting of building should be drafted and vali-dated in greater detail to generate the 3D BIM Model in the AutodeskTM Revit®. The 2D floor plan and elevation of the 3D BIM Model of G+20 High-rise building considered for the purpose of this research is in Fig 6-8.

Figure 1: CAD diagram of the wall panle using AutodeskTM AutoCAD®

Figure 2: 3D BIM of the wall panle using AutodeskTM Revit®

Figure 4: Altering the height of the developed 3D BIM wall panel

Figure 5: Adding other materials to the developed 3D BIM wall panel

Figure 6: 2D floor plan of G+20 high-rise building

Figure 7: 2D elevation of G+20 high-rise building

Figure 8: 3D BIM of G+20 high-rise building

The CAD diagram of the Wall Panels developed using the AutodeskTM AutoCAD®, as in Fig 1. It is simpler and takes a considerable time in drafting. Thus, the same wall panel when drafted using 3D BIM software has additional advantages such that it could be altered without editing the panel drawn, tex-ture could be applied to the panel and even different material properties could be assigned to the panel. Thus, the 3D BIM is more sophisticated technique than the conventional CAD systems for the parametric change characteristics and to imparting coordination among the other construction per-sonnel involved in the project. The 3D BIM of the wall panel and its intriguing characteristics are in Fig 2-5.

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3D BIM Formwork Family

To incorporate formwork systems in the 3D BIM Model, the procedures adopted are as follows.

- Conversion of solid 3D BIM Model into wireframe model, which acts as a reference for formwork insertion as in Fig 9.

Figure 9: Conversion of 3D solid BIM to 3D wireframe model

Figure 11: Conversion of 3D solid BIM to 3D wireframe model

Figure 12: Conversion of 3D solid BIM to 3D wireframe model

Figure 13: Conversion of 3D solid BIM to 3D wireframe model

Figure 14: Incorporation of 3D revit wall formwork family into the 3D BIMFigure 10: Conversion of 3D solid BIM to 3D wireframe model

Components Family is preferred. It is used to customize the formwork systems, add texture, and assign material prop-erties and so on.

Besides the formwork systems, the 3D BIM of the as-sociated formwork accessories, such as external support-ing systems such as beam forming support, shore or prop,

- The formwork components are drafted as the Revit fam-ily files (.rfa files) using the AutodeskTM Revit® Family Editor, which is similar to the Block in the AutodeskTM AutoCAD®

- Once the family files are created it is then loaded into the project that is the generated wireframe model.The detailed descriptions of the method and techniques

for creating the 3D BIM Revit formwork families are illustrated in the Fig 10-13.

Automated Layout of Concrete Formwork System

Unlike 3D BIM of structural systems, the formwork sys-tems are drafted using the AutodeskTM Revit® Family Editor. The 3D BIM of the structural systems are the System Family files, also known as in-built files available in the software that cannot be customized as in Fig 10.

However, custom treatment is required for developing formwork modules, so the specialized Revit family knows as

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Figure 15: Incorporation of 3D revit column formwork family into the 3D BIM

Figure 16: Incorporation of 3D revit beam formwork family into the 3D BIM

Figure 17: Incorporation of 3D revit slab form family into the 3D BIM

Figure 19: Final 3D BIM of G+20 high-rise building after the incorporation of all 3D Revit formwork families

Figure 22: Final concerte formwork layout (after parametric change)

Figure 23: Transfering 3D BIM revit model to autodesk navisworks

Figure 20: Finsihed 3D BIM with all formwork families

Figure 21: Parametric change capabilities of BIM by replacing 3D tradition-al formwork family by 3D system formwork family in the 3D BIM

Figure 18: Fully incorporated 3D Revit formwork families in the 3D BIM

external alignment struts, etc., can also be created using the method described for the formwork systems. However, these systems are optional.

Parametric change characteristics using BIMThe generated 3D BIM with all the 3D formwork families

incorporated in it are a great tool in formwork construction. Nevertheless, its importance could be also enhanced by the additional parameters such as external supporting struts and alignment props and so on. The fully finished layout of con-crete formwork systems is given in Fig. 19.

Thus to reinforce the importance of BIM, the parametric change capabilities of the BIM is checked, it is done by the replacing the traditional wall formwork generated previously

in the BIM by the system wall formwork as in Fig. 21. For additional interoperability, the 3D Revit model is transferred to Autodesk Naviswork as in Fig.23.

In the AutodeskTM Naviswork®, the real-time simultion of formwork systems as in Fig.24 and clash detection can be performed so as to vizualize the schedule and flaws that could happen during construction phase respectively. This also

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Figure 24: Simulation of 3D BIM in AutodeskTM Navisworks®

Figure 25: 4D Schedule of the G+20 BIM model from AutodeskTM Navis-works®

Figure 26: Oblique view of the elevation of the project

Figure 27: 3D BIM with Mivan modular formwork module for the project

Figure 28: 3D BIM Revit family for table formwork system

Figure 29: 3D BIM Revit family for climbing formwork system

Figure 30: Visualizing constructability issue in 3D BIM

useful not only for nmaking appropriate selection of formwork systems and accessories, and to settle the as-built discrep-ancies that could arise between the construction personnel during construction phase but also to compute 4D schedule as in Fig.25 and 5D cost of the project.

The concept of BIM on formwork system is incorporated in a real-time project, Navins Starwood Towers, Chennai., a fully equipped residential condominium with 958 apartments that is a mini vertical 14 floor township with basement plus stilts spread across eight towers. In this project, one of the towers named Chestnut was used for the study. The type of formwork systems used for the construction is modular formwork system from Mivan.

Summary

The incorporation of system wall formwork does not in-fluence or alter the previously developed 3D formwork lay-out BIM and from the actual construction perspective it im-

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proves the conditions of construction factors like time, safety and sustainability. Thus BIM is really a paradigm shift in the drafting and layout of formwork systems.

The 3D BIM model of structural components considered in this article is a generalized model however for advanced research on formwork systems; more complex 3D BIM models are developed for studying additional parameters.

The formwork systems presented in this article are cus-tom made for the purpose of this research and it is more simplified systems, thus for a detailed study on the actual formwork systems, the readers are advised to incorporate the available patented formwork systems in the BIM. The other types of formwork systems such as table formwork system, climbing formwork system as in Fig.28-29, Slipform and other movable type of formwork systems can also be in-corporated using BIM. Besides the formwork, the falsework associated with the construction of formwork such as scaf-folding, shoring and other formwork accessories can also be incorporated to study the temporary structures of the con-struction as a whole. BIM based formwork layout enhances the overall profitability of the formworks systems by even incor-porating constructability checks during formwork planning and designing phase. The openings and other critical factors in the structural elements are sort out using BIM as in Fig.30.

References

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3. Meadati, P, Irizarry, J. and Aknoukh, A. BIM and concrete formwork repository. In Proc: 47th ASC Annual International Conference Pro-ceedings. 2011.

4. Jun, K. H., & Yun, S. H. (2011). The case study of BIM-based quantity take-off for concrete and formwork, Journal of Korean Institute of BIM, 1(1), 13-7.

5. Kim, T., Lim, H., Lee, U. K., Cha, M., Cho, H., and Kang, K. I. (2012). Advanced formwork method integrated with a layout planning mod-el for tall building construction. Canadian Journal of Civil Engineer-ing, 39 (11), 1173-1183.

6. Chi, S., Hampson, K. D., & Biggs, H. C. (2012). Using BIM for smart-er and safer scaffolding and formwork construction: a preliminary methodology. Modelling and Building Health and Safety.

7. Kim, K., & Teizer, J. (2014). Automatic design and planning of scaf-folding systems using building information modeling. Advanced En-gineering Informatics, 28(1), 66-80.

8. Kannan, M.R., Santhi, M.R., Automated Construction Layout and Simulation of Concrete Formwork Systems Using Building Infor-mation Modeling, in: Proc. 4th International Conference of EACEF, National University of Singapore, Singapore, 2013, pp. C7-C14.

9. Kannan, M.R., Santhi, M.H., (2013) Constructability Assessment of Climbing Formwork Systems using Building Information Model-ing, Procedia Engineering, Elsevier, 64, 1129-1138, http://dx.doi.org/10.1016/j.proeng.2013.09.191.

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