CHAPTER II

 

BUILDING CONSTRUCTION PROCESS INTEGRATION

 

2.1. Introduction

The integration of design, planning, and construction offers important opportunities to improve performance on engineering and construction projects.  This integration requires Information Systems (IS) that supports the communication between the different participants.  Nowadays most participants in a building project perform their activities aided by computers.  In contrast, the communication between participants is carried out in the majority of the projects with conventional media (for example through drawings, specifications, etc.).  The process of interpreting and understanding the exchanged information is carried out by human beings.  In order to improve this situation, it becomes mandatory to support this exchange of information by IS.  This implies the use of models for representing the different participants in the construction process and standards to exchange the model’s data.

 

2.2. Coordination Between Participants

 

The building process is often seen as a linear process from early investigations to the maintenance phase [1].  The main phases, as a rule, are broken down into sub-phases.  Planning and design are activities pertaining to a model of a future building to be erected.  The construction phase is oriented to producing the building itself.

 

The planning and design phase can be represented by means of Figure 2.1 

 

 

Fig. 2.1. Planning and Design Phase as a Function of Time. 

 

2.2.1 Coordination Between Producer and Designer

For the introduction of information and automation technology in the construction industry, the first element that is necessary to analyze is the coordination between producer and designer.  As was stated in the previous Chapter, it is desirable to increase, as much as possible, the share of construction work that can be performed at an off-site facility. 

 

The following material, related to the pre-fabrication process, is extracted from “Industrialization and Robotics in Buildings”. [2].

 

The economy of pre-fabrication, for any building project, may be enhanced by an effective coordination between designer and producer.  The basic communication alternatives between these two participants are:

 

1        Production is based on the architect’s design, with little or no regard to the pre-caster’s consideration.

 

2        Production is based on the pre-caster’s own design, for a general or a specific type of project, in most cases made to suit the requirements of a certain group of clients.

 

3        Production is based on a design that observes some general coordination rules, with respect to dimensions and location of elements.  Pre-casters adapt the production of elements to the same rules.

 

4        Production is based on a design prepared by the client and following some common rules that ensures its adaptation to the particular producer’s component system.

 

1)      Production based exclusively on architect’s design.

 

This implies a high cost in detailed design of components, adjustment of molds, etc. that can be only justified by a large enough production series for each element.

If the design disregards the specific constraints of the eventual pre-caster, the project may put pre-fabrication at an initial disadvantage with respect to conventional methods.

 

2)      Production based on pre-caster’s design.

 

This means a closed pre-fabricated system and the main problem will be the demand.  If it can attract a big number of orders over a long enough time period, it can be economically successful.

This type of construction has been applied in countries where centralized planning could adapt the system to prevailing explicit norms and assure its universal use.

 

 

3)      Dimensional Coordination.

 

In view of the limitations of the former approaches, it is logical to think of a method that satisfies  the needs of both the designer and the pre-caster.  This system may be thought as an “open system” (this refers to the interchangeability of components of different products and technologies) of interchangeable elements, which could be supplied by different producers and could be used in any type of design conforming to the basic rules.  The objectives of the modular coordination are to:

 

·        Reduce the variability of the dimensions of building components.

 

·        Allow for easy adaptation of pre-fabricated components to any layout and for their interchangeability with the building.  For an open system design, it is necessary to clearly define the permitted deviation rate or tolerance for the production.

 

A clear definition of the permitted deviation rate or tolerance for each element should be defined for both the production and erection processes.  Assuming the possible deviations, eventually affecting the position of an element with respect to its control line, as statistically independent of each other and following a normal distribution within the limits of their tolerance, the standard deviation s of the resulting position deviation is given by:

 

s = Ö [ (s₁)² + (s₂)² + ___ ]

 

where s_1, s_2, -- are the standard deviations in the position of an element due to the effect of each pertinent factor independently of others.

 

There are five rules that can be accepted in the standardization process of the dimensional coordinator:

 

·        The Controlling dimensions of horizontal components- slabs, beams, and girders – are limited to multiples of preferred multi-modules.

 

·        The controlling dimensions of vertical envelope components – exterior walls, columns, and cladding – are limited to the preferred sizes of overall floor height or derived form preferred sizes for the interior height.

 

·        The controlling dimensions of interior vertical components – bearing walls and partitions – are limited to the preferred dimensions for overall height.

 

·        The thickness of walls, slabs, and the cross-section of beams and columns are limited to multiples of a basic module or preferred sub-modules.

·        The controlling dimensions for doors, windows, stairs, and some other interior fixtures are limited by their preferred sizes.

 

There exist two main reasons that hinders the use if the “open system” concept:

 

Ø      Differences in joints and connections.

Ø      Non-modular and non-uniform thickness of key building components such as walls and floor slabs.

 

These difficulties could  be overcome by a nationwide or worldwide introduction of a true open system.

 

Another concept is the integration of the concepts of closed and open systems in an “open-closed” or “flexible” system.  This is a closed system in a sense that it employs a finite set of components produced, erected, and connected in a specific method.  The system, however, conforms to general requirements of modular coordination and is devised in such a way that it leaves an architect with considerable freedom of design.  These ends are attained by a selection of appropriate design multi-modules, which on the other hand considerably restrict the number of variants of main components - floors, slabs, interior and exterior walls – and on the other hand, allow generation of a maximum number of useful layouts of a desired type. The development of a flexible system involves a choice of components to be employed in the system and their sizes.  A systematic design method, which was developed by the SAR (Stichting Architecten Research) Group is described in the cited reference for this part, and can be used for selection and evaluation of design modules in many types of residential and other buildings.

 

2.2.2. Coordination During the Construction Process

 

For the introduction of information and automated technology in the whole process, it is mandatory to have explicitly defined all the tasks and relations in the construction process. Figure 2.2 represents the different parts in which the construction process may be divided [1].

 

 

Fig. 2.2. The Construction Process.

 

As was stated by several authors, the central problem of coordination arises from the fact that the basic relationship between the parties to a construction project has the character of an interdependent autonomy.  There is a lack of match between the technical interdependence of the work and the organizational independence of those who control the work.

 

There exists a high number of coordination of activities, which construction project managers not always can identify.  These activities are numerous and miscellaneous in nature.  They neither could identify specific customers nor specific inputs/outputs of their processes and claimed that the customers of a construction project manager are so numerous because he (she) has to work with every participant of the project and every outsider connected with the project, each having unique needs.  It may be that the informal character and intangibility of construction coordination have made it very difficult for the practitioners to establish a model of the process itself.

 

An attempt to present the problem in a mathematical form [1] is obtained dividing the building or facility into conceivable parts (work sections) or activities (A) resulting in finished elements (D) these activities require resources (R) of different kinds.

 

Resources (products, human effort, etc.) are handled and refined on the site throughout a large number of systematic activities.  The combination of a set of resources and an activity produces a finished element.  The total result, the building, is presented as the sum of all finished elements:

 

 

Where <--- indicates and assignment and its direction.  The final result of manufacturing, P, the complete building is:

           

Where D_i is the i^th finished element.

A_i is the i^th activity

R_i is resources pertaining to A_i

n is the number of parts in which the construction project is divided.

Including the relationships among the different parts, it is possible to define C as a complimentary product or function and the building product will be expressed by

 

       

Where Cij is the influence of the i^th element on the j^th element , a relationship that must be in order, otherwise the building P cannot be accepted.

2.3. Product Modeling for the Building and Construction Industry. 

A goal of current research is to develop one or more computer representations of building information that can supplant all the current documentation now residing on paper.  This information ranges from drawings, written specifications, spreadsheets, databases, etc.

 

“The potential benefits of modeling the building information include the improvement of information availability, supporting an open-ended set of further analyses and applications, reducing the space and time to store and transmit information, and at the same time to expand the base of information” [3].  Whole electronic communications for sharing and storing project information is currently difficult, if not impossible.  Consequently, all participants in a specific project are required to convert computer- generated, electronic information into paper-based output.

 

The building and construction industry requires a complete and adequate electronic project information system.  One of the tasks for the completion of this goal is the creation of standards, but if standards are not adopted by a significant number of users, it does not solve many problems. ISO 10303 STEP is a real intent of solving the problem.  “STEP allows companies to effectively exchange information with their worldwide partners, customers and suppliers, as well as internally.” [5].

 

STEP is an acronym, which stands for the Standard for the Exchange of Product model data.  It is part of the International Organization for Standardization (ISO).  It was developed by ISO TC 184/SC4 (Industrial Data).  According to Fritz P. Tolman [4], “The coming years will show that STEP is using outdated technology that will prove to be ineffective for the building and construction industry.  ISO is not the optimum organization to steer the pre-standardization process and there is not even a consensus among the researchers that are carrying out the efforts”.  From this, one can see that everybody does not support the use of the ISO standard.  Only in the future will the decision to take become clear.

 

The other alternative also presented in the same work is to abandon the development of standards but solve the problem by providing a service.  OMG (www.corba.com) allows a service provider to assist the participants of a building and construction project in setting up a dedicated and distributed project database.  The OMG was formed to create a component-based software marketplace by hastening the introduction of standardized object software.  The organization’s charter includes the establishment of industry guidelines and detailed object management specifications to provide a common framework for application development.  Conformance to these specifications will make it possible to develop a heterogeneous computing environment across all major hardware platforms and operating systems.  Implementations of OMG’s specifications can be found on many operating systems across the world today.  OMG’s series of specifications detail the necessary standard interfaces for Distributed Object Computing.  Its widely popular Internet protocol IIOP (Internet Inter- ORB Protocol) is being used as the infrastructure for technology companies like Netscape, Oracle, Sun, IBM and hundreds of others.  These specifications are used worldwide to develop and deploy distributed applications for vertical markets, including Manufacturing, Finance, Telecoms, Electronic Commerce, Real-time Systems, and Health Care.

 

Another example for the use of INTERNET in the construction industry is the effort done by Bentley Systems, Inc. launching Viecon.com Project Extranet [17]. The project is focused on maximizing the effectiveness of Engineering, Construction and Operations (E/C/O) networks by allowing members of project teams to create, communicate and collaborate efficiently over the Internet. “It provides a real-time, interactive environment for comprehensive, project life cycle management of all the tasks and documents associated with a project. In use, you can create and manage projects with a comprehensive suite of scheduling, tracking, meeting, and calendar-based software. Meetings may be physical (in a single site), teleconference, or on-line, interactive, where the host's screen is visible to all participants. In addition, there are downloadable tools for viewing drawings, sending drawings over the web as emails, and a conversion tool for maintaining data for DGN, DWG, and DXF formats.”

 

In order to use effectively these tools, it is mandatory to have general concepts about building models, life cycle and the necessary information needed on each stage of the construction process.

 

For any building it is possible to define five stages [3]:

 

1)      Feasibility study

2)      Design

3)      Construction planning

4)      Construction

5)      Operation

 

The feasibility study is the generator of the building model and thus influences the design and later stages.  This stage also plans and set goals, at a general level, for all the other stages.  This stage defines the purposes of the building project and assesses if the resources are appropriately matched with the project scope.  At this stage, the costs are balanced with the function of the building.  The planning at this stage of the building model often involves developing many different feasibility models and comparing them in different dimensions.  The following four tables are reproduced from the same paper.  Table 2.2 presents the different parameters to take into account and the type of data necessary for this stage. 

 

Table 2.2 (Source Eastman, 1993).

Applications and Data to be Supported During the Building Feasibility Stage.  

 

 

 The design involves the translation of functional criteria developed in the feasibility models into detailed descriptions of the building project to allow fabrication and process planning.  Design also involves assessing that the facility will achieve its intended functions.  Table 2.3 shows the different activities and the type of data necessary in this stage.

 

 Table 2.3. (Source: Eastman, 1993)

Applications and Data to be Supported During the Building Design Stage.

The construction-planning phase involves the bidding and tendency processes that develop a construction plan and estimated construction costs.  Empirically divided databases are very important in this stage, for dealing with materials and labor costs.

 

These units of work and material are the basis for cost estimates and later procurements and scheduling.  Detailed investigation of the construction site is carried out at this stage, including borings and geological investigations.  Table 2.4 shows tasks and type of data necessary in this stage.

 

Table 2.4 (Source: Eastman, 1993)

Applications to be Supported During the Construction Planning Stage.

 

 

 

The construction stage executes the construction plan.  In the future, it is possible to expect that each subcontractor will receive a design model of the building component, from which they will define both a detailed fabrication design and a process schedule for their components, for both on - and off - site work.

 

Table 2.5 shows the tasks involved in this stage, and the necessary type of data.

 

Table 2.5. (Source Eastman, 1993).

Applications to be Supported During the Construction Stage.

 

 

2.5. Conclusions

 

1.      To be able to integrate the construction process, it is mandatory the use of models for representing the different participants in the construction process and standards to exchange the models’ data.

 

2.      A way of solving the differences between designers and pre-casters is the creation of open systems of interchangeable elements, which could be supplied by different producers and could be used in any type of design conforming to the basic rules.

 

3.      There exist two tendencies in the product modeling in the construction industry.  One is the creation of standards like ISO 10303 STEP, and the other is to use companies that provide this service like the OMG.

 

References

 

1.      Keiger Ulf. “Building Integrity: Classification Beyond Building Parts and Spaces.” Proceedings of the 1^st International Conference on the Management of Information Technology for Construction.  Singapore, August 1993.

 

2.      Warszawski A. “Industrialization and Robotics in Buildings.”  Harper and Row Publishers, August 1993.

 

3.      Eastman Charles M. “Life Cycle Requirements for Building product Models.”  Proceedings of the 1^st International Conference on the Management of Information Technology for Construction. Singapore, August, 1993

 

4.      Web site: http.tiger.aticorp.org/10303.html.

 

5.      “ BJORK, B “ A case study of a national Building Industry Strategy for Computer integrated Construction” Laboratory of Urban Planning and Building Design, Technical Research Centre of Finland, VTT.”

 

6.      “Tolman .F & Poyet. P  “ The ATLAS models” Proceedings of ECPPM ’94 ---the first European  Conference on Product & process modeling in the building Industry , Dresden  , Germany , 5-7 October 1994”

 

7.      Website: http://www.corba.com

 

8.       Website: http://viecon.com.