The Future Development of Information Systems for Steel Construction

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STEEL CONSTRUCTION: COMPUTER AIDED DESIGN & MANUFACTURE

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STEEL CONSTRUCTION:

COMPUTER AIDED DESIGN & MANUFACTURE

Lecture 5.2: The Future Development

of Information Systems for Steel

Construction

OBJECTIVE/SCOPE

To discuss possible future developments in data transfer between different stages in the

steel construction process, through a product model approach. To indicate the benefits that

might be realised as a result of this and how such changes can be achieved.

PREREQUISITES

Lecture 5.1: Introduction to Computer Aided Design and Manufacture

RELATED LECTURES

None.

SUMMARY

The processes of exchanging information at various stages of a steel construction project

are reviewed briefly. The potential advantages of enabling this transfer to be made directly

between computers rather than, as at present, on paper are outlined. The basic

requirements that must be met before such a system can be implemented are discussed in

principle, and the practical ways in which it might be achieved are considered. The role ofthe management information system is explained, and a realistic approach to

implementation throughout the industry is outlined.

1. INTRODUCTION

The progress of a building project from client's brief to completion of execution entails the

generation and transfer of large quantities of information, much of it in the form of paper

documents. Many people contribute to the project as it progresses through its various

phases.

Inefficiency and disruption results from the need to translate information from one formatto another - as occurs, for example, in the creation of workshop drawings for the steel


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fabrication - as well as from the transfer of inadequate or erroneous information, and from

late changes which may entail laborious reworking.

The aim of this lecture is to extend ideas relating to information exchange standards,developed for manufacturing industry, to the processes of information transfer between the

various stages of construction, in order to render these more efficient and economical.

2. INFORMATION EXCHANGE IN THE

CONSTRUCTION PROCESS

2.1 Information Exchange: The Present

Figures 1 and 2 give an indication of the information generated and exchanged within the

construction process, and the various parties which may need to be involved in such

exchanges of information. Figure 3 represents a portion of this information schematically,

using the terminology of the Product Model - the product being in this case the steelwork

aspect of the building project. This figure marks the stages in the life of the product, and

illustrates the accumulation of product data as product life progresses. Information

exchanged between phases often has particular legal significance. A particular example is

the set of information exchanges which take place at the end of the design phase and

which are marked by the signing of a contract. There is a particular onus on the

participants to ensure the completeness, correctness, clarity and finality of suchinformation exchanges, as errors can waste time and money and variations lead to

contractual claims.

Common sense would suggest that the quantity of information exchange should be

confined to the essential - consistent, of course, with the conveyance of an adequate

understanding of requirements.

At present this information is exchanged between participants as hard copy, i.e. as reports,

calculations, drawings, etc. Interpreting this data at each stage of information exchanged

can be a time consuming process, particularly if there are ambiguities, or if some aspectsare incomplete. Modifications in the information generally result in changes within all

subsequent stages of the product model route. Changes in the client brief, for instance,

cause reworking of design calculations, drawings, details, etc. and if made late in the

programme can result in significant delays. Substitution of alternative section sizes at the

detailing stage to take account of material availability, for example, may have less

consequence, but even so the required changes to details may be time consuming. It is

always a danger too that isolated changes have implications for other aspects of

construction which are not identified in the rush to make the corrections. Something as

simple as a change in beam depth, for instance, may have considerable significance for the

accommodation of services.


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The present system does, however, provide useful opportunities for checking information

since at each stage of information transfer the data is examined afresh. It also allows forconsiderable flexibility in the system, with some information being passed on in a partially

complete form, and in a variety of formats. Feedback between later stages in the product

model route and those earlier in the process are also relatively straightforward.

2.2 Information Exchange: The Future

More use is being made of computers within each stage of the product model route, with a

view to increasing efficiency. One of the most time consuming aspects of using computers

is entering data, and significant savings can therefore be achieved if the effort required for

data input is minimised. This can be achieved by transferring data between successivestages in the product model route electronically rather than as hard copy.

Future information exchange will therefore involve wider use of computers to reduce

manual input of data and provide a better flow of information relating to the steelwork

'product'. For instance information derived from design calculations could be transferred

directly to a computer-aided design (CAD) system to avoid duplicating definitions of basic

data such as beam spans, column heights, etc. and to enable the output from the

calculations (section sizes, beam reactions, etc.) to be taken directly into the next stage.

Some developments have already taken place in this sense. The integration of general

arrangement drafting and detailing systems, and the output of 3-D modelling systems

leading directly into numerically controlled machines for fabrication. This meansreplacing the present limited conventions and protocols for information exchange, both

manual and computer based, with a more rigorous unified information exchange system


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which can apply across the entire construction industry, and which is capable of operation

in all phases of the project's life.

Such a system requires:i.the establishment of a unified computer based product description.

This requires data in a sufficiently comprehensive form to describe all relevant aspects

of the product at all stages.

ii. the creation of standards for the transfer of information between different computer

systems and organisations.

iii. the creation of information management systems - to control information changes,

access rights and quality assurance.

These requirements can be illustrated by the following simple examples:

i.A computer program for the elastic analysis of frames requires member cross-sections to

be described in such terms as area and moment of inertia. It does not require a

description of how the area is distributed throughout the section, i.e. what its shape is.

Such a description would, however, be inadequate to generate connection details. It is,

therefore, desirable to have a single format which would accommodate both needs,

permitting an efficient transition from analysis to drafting.

This is a somewhat trivial example. Most frame analysis programmes now allow

definition of cross-sections by reference to a standard library. However it does illustrate

the point that data which is sufficient to describe the product at one particular stage in

the process may be inadequate for other stages.

ii.Working on a range of products, a steelwork fabricator has to produce shop drawings

from engineering design information originating from a variety of software and

hardware systems, some of which are mutually incompatible. It would seem

advantageous if this fabrication could access directly the graphical information base

created by the designer in each case. This would necessitate a CAD system capable of

information exchange with all others on the market. CAD developers have tended to

concentrate on transfer of information between computers running the same software,

i.e. theirs, rather than facilitating exchange of information with machines running

software produced by a competing CAD developer. An information exchange format

which is particular to a CAD package is termed the 'native' data exchange format of that

system.Considerable progress has been made in this direction with regard to alphanumeric data.

The ASCII format provides a basic standard so that text produced using one

wordprocessor system, for instance, can be output in this form enabling it to be read

directly by other systems or application programs. Dealing with text is a relatively simple

matter because it involves a limited number of unique characters. Even so, the ASCII

standard provides for the basic characters only with no formatting signals to indicate

different text styles, subscripting, etc. Data for presenting information graphically is even

more complicated, but some standards have been established, IGES and DXF files serve a

similar function, providing a standard of data appropriate to drawing instructions, enabling

the output from the CAD system to be interpreted by another. However it should be clear

that this is not in itself sufficient to provide a full description of what is being drawn. The

full product model description requires much more complete information.


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3. A FRAMEWORK FOR CHANGE

3.1 The Product Model

An essential first step towards an integrated approach is the development of a standard

specification for the organisation of technical information on structural steelwork. This

specification is referred to as the 'logical product model' and provides a standard basis for

the production of interfaces between structural steelwork software products. When the

technical information on a particular structural steelwork contract is arranged according to

the 'logical product model' specification, it is then simply referred to as a product model.

The product model approach can be used to transfer information between all sorts of

software products by using product model files (computer files) to transfer the information

automatically. Consistent versions of existing paper documents can then be generated, as

required, from this unified digital description, or product model.

In broad terms, the system would work in the following way:

Each software product concerned with structural steelwork would have its own

product model interface.

Product model files would be used to transfer information between the various

software products.

The product model interfaces would read information from, and write information

to, the product model files as and when required.

Figure 4 compares the traditional approach with the product model approach for

information exchange. The main advantages of the product model approach are that it will

offer flexibility for users to configure and develop systems from the software products

they prefer (provided each product they wish to use has a product model interface).


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A product model for steelwork construction is currently being developed within the

Eureka EU130 CIMSTEEL project.

In the long term, the approach is capable of being developed to achieve full databaseintegration of software products. It is the target system architecture activity which aims to

map out the future part of development.

3.2 Information Exchange Between Software Products

3.2.1 Introduction

The native exchange file formats are 'de facto' standards established by particular software

vendors and remain under their control. In contrast, the concept of a neutral file format

implies a universal standard independent of any particular vendor. Such standardsoriginate typically from research projects but are now increasingly coming under the

control of international standards bodies.

One of the principal goals of current research projects, e.g. EUREKA, ESPRIT, is to make

it possible to transfer information easily and inexpensively between the many different

software products already available or being developed for the structural steelwork

industry. This implies direct digital transfer of information obviating the need for manual

interpretation of drawings, etc.

Examples of software products involved are:

Structural analysis programs.

Computer aided design and detailing systems.

Software for programming of NC (numerically controlled) machines, tools, e.g.

sawing, drilling, flame cutting, and profiling machines.

Software for programming of welding cells.

Company MIS (management information systems) and software for cost

estimating.

The main benefits of linking software are that time and effort can be saved, and

transcription errors can be eliminated.

Traditionally, wherever a company requires an efficient means of information exchange

between specific software products, a new piece of purpose-written software, 'an

interface', has to be produced. Unfortunately, an interface will only work with the

particular pieces of software for which it was specifically written in the first place. Thus,

every time a new software product is introduced, new interfaces have to be produced to

link with each and every other piece of software with which it needs to exchange

information. The simple interface of two pieces of software solves only a local problem

and creates a localised increase in efficiency (Figure 5). To achieve a solution to meet the

requirement of the whole industry a wider perspective is required.


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3.2.2 'Neutral' graphical exchange file formats

The IGES Standard

The most widely supported of the current generation of neutral exchange file formats is

the Initial Graphical Exchange Standard (IGES). It originated in 1980 with the then United

States National Bureau of Standards. By 1988 Version 4.0 had been published, and at the

time of writing this lecture, a final version - to be Version 5.0 - is awaited. While IGES

has extended its ability to represent information and addressed problems of efficiency, the

standard has grown increasingly complex. It is similar in principle to the DXF system,

which is a proprietary product of Autodesk.

The neutral file concept established by IGES led to the evolution of several other data

exchange standards, each targeted on the needs of a specific group of CAD/CAM users. In

each case, the objective was to make the exchange process more efficient and reliable, and

to maximise the ability of the developed data exchange file format to represent particular

classes of engineering information.

While considerable technical progress was made by these various standards projects, the

result was a proliferation of data-exchange formats. It was recognised that the solution lay

in a single second-generation neutral file standard which would provide a unified

framework for data exchange by all sectors of engineering. The result was the new

emerging International Standards Organisation (ISO) STEP Standard.

The ISO STEP Standard

STEP, the Standard for the Exchange of Product model data seeks to provide consistent

data models across a broad range of engineering applications which would be applicable

to the whole life-cycle of engineering products. Thus the STEP data models will

(eventually) enable all aspects of a construction project to be represented, from conception

through to the structure's ultimate demolition.

So in some respects, STEP is just another neutral data exchange file format. However, the

true significance of STEP is that it uses much definitive second-generation engineeringdata exchange standards based on the concept of a product model. It is interesting to note

that during the early development of IGES it was 'Product Data' that was to be exchanged.

The switch to 'Product Model' in STEP reflects a recognition that it is information (i.e.

meaning), not data, that has to be transferred (see Figure 6).


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Currently, STEP is little more than a powerful enabling technology and, while it may be a

long-term task to compile the necessary component product models, the technology for the

implementation of STEP will soon be available [1, 2].


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3.3 Management Information Systems (MIS)

To make real progress in the area of the future management information systems it is

necessary to have a clear and common view of how it relates to the product model. Themain point to recognise is that the product model is limited to technical information.

Management information must be dealt with separately by the MIS.

Figure 7 presents a simplistic view of the structural steelwork design and manufacture

process with boxes representing the functions of scheme design, detail design, fabrication

and erection. Types of software products which may be used are shown under each

function. At the top of the diagram is the Management Information System, which

monitors and controls the functions. At the bottom of the diagram is the Product Model

which provides the technical information needed by the software products in the form of

product model files.

Although a clear division between technical and management information can be defined

theoretically, in reality the MIS will need to:

Know where all technical information is located and organised.

Monitor and control all modifications to Product Model information.

Monitor and control all Product Model file transfers to and from the software

products.


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Thus, in addition to a 'management information controller' the MIS should also include a

'product model information controller' whose function will be to manage the flow of

product model information in the form of product model files. Figure 8 illustrates the way

in which this could be arranged. In essence, the MIS controls both the managementfunctions and the transfer of product model information. Product model files are stored in

the product model file store and are used to transfer technical information to enable the

various pieces of technical software to perform their required operations for any particular

contract going through the factory.


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It should be noted that Figure 8 represents product model file interfacing, and does not

include database integration of products model information. As such, it can only represent

a step towards the development of fully integrated systems.

4. IMPLEMENTATION

Incremental Implementation

It has to be fully recognised that many of these long term aims have only a theoretical

meaning today. As a result practical incremental implementation is essential so that the

industry can start to reap the benefits in the shorter term. The shorter term goals of

common information exchange standards allow the interfacing of systems enabling the

industry to take the first vital steps towards implementation of computer integrated

manufacture (CIM).

Recognising the different ways in which steelwork companies are managed, and will

continue to be managed, it is evident that an all encompassing standard for management

information is going to be very difficult to achieve.

However, if the finance, sales and marketing, personnel, and administration functions are

excluded for the time being, then a common approach is feasible for:

Contract planning.

Capacity planning.

Process planning. Design control.

Materials control.

Fabrication control.

Despatch/transport control.

Erection control.

It is in these areas that an industry-wide approach could be developed. An industry MIS

could be produced covering these functions which would comprise a number of modules

operating in conjunction with a management information database and a product model

file store.

5. CONCLUDING SUMMARY

Computer aided transfer of standard product information between design and

fabricator will reduce time for information production, detailed design and the

production of fabrication drawings, as all required information can be transferred

automatically.

The net result will be significant increases in efficiency due to the reduction in

contract variation claims and hence a less contentious contractual relationship.

Controlled early access to relevant information and changes to information has

great advantages in reducing lead times and errors.

This future development will result in a dramatic change in the nature of

estimating with respect to current practice. The fabricator will receive standard


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items of product information, files of historical manufacturing (material and

workmanship) cost data for each item. The 'scientific' part of estimating can thus

be automated. Commercial judgments on an estimated contract value can then be

applied in the more certain knowledge that estimates are correct. There are four key requirements for the structural steelwork industry to enable the

effective and efficient transfer of product information. These are computer-based

product descriptions, international information exchange standards for structural

steelwork (neutral exchange file formats), and information control (management

information systems).

These developments represent a fundamental change in current methods of

working. Acceptance by the industry can only be achieved by the introduction of

short term solutions which lead towards the ultimate goal.

6. REFERENCES[1] National Economic Development Council (NEDC), Information Transfer in Building,

NEDO, London, 1990.

[2] Watson, A. S., CAD Data Exchange, Proc. Institution of Civil Engineers, Part 1, 1990,

Vol. 88, December, 955-969.

The Future Development of Information Systems for Steel Construction

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