THE DEVELOPMENT OF A WEB BASED MULTIMEDIA INFORMATION SYSTEM FOR BUILDING APPRAISAL

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1 THE DEVELOPMENT OF A WEB BASED MULTIMEDIA INFORMATION SYSTEM FOR BUILDING APPRAISAL Dominic O' Sullivan Department of Civil & Environmental Engineering National University of Ireland, Cork. Dr. Marcus M. Keane Department of Civil & Environmental Engineering National University of Ireland, Cork. ABSTRACT: Construction work undertaken on existing structures accounts for 30% of building projects in Ireland and as much as 50% in Europe. Engineers, however, have in the main been educated and trained in the art of designing new structures and most are unaware of the significant differences involved when dealing with the appraisal of existing structures. A web compatible multimedia information system (MMIS) offers an effective environment in which to educate engineers on the various issues that arise in dealing with the appraisal and renovation of existing structures. The MMIS provides information and instruction relating to the process of building appraisal according to the standards set out by the Institute of Structural Engineers (IstructE). The objective of this paper is to specify the software requirements for such a web based multimedia information system. The MMIS will be specified using formal methods based on proven Software Engineering Methodologies. KEYWORDS: Structural Appraisal, Web-compatible Information System, Object- Oriented, Multimedia, Unified Modelling Language. INTRODUCTION In recent years construction work undertaken in building renovation and rehabilitation has increased considerably [Whelton et al., 1998]. Attitudes towards building conservation have changed accordingly and people no longer take it for granted that a new building will be an improvement on the one that it is intended to replace. In Ireland 30% and in Europe as much as 50% of all construction work is undertaken on existing structures, reflecting the common modern day philosophy of "repair rather than replace" [Whelton et al., 1998]. The number of engineers involved in work on existing buildings has therefore increased considerably with the result that the reuse of existing structures to suit modern day requirements has become an important aspect of the building industry. Engineers, however, have in the main, been educated and trained in the design of new structures and most are unaware that although the scientific principles do not differ the application of these principles to an existing structure is not as simple as it might first seem [Holland, 1992]. One notable difference is that visual inspection becomes an extremely important skill when dealing with existing structures. By developing a web

2 compatible Multi-Media Information System (MMIS) on building appraisal the Engineer will be made more aware of the options available to him/her and be advised insofar as is possible to the best method of practice for his/her particular situation. The multimedia aspect of the information system is of particular importance given the role that visual inspection / observation plays in building appraisal. In our present information age the world wide web provides us with an ideal medium for making this information as widely available as possible. Web compatibility will enable remote (on-site) access to the information system via palm top technology. This is ideal given that many decisions relating to building appraisal have to be made on site. Furthermore the web provides us with an environment that is ready to incorporate the various types of media to be used in the MMIS. By exploiting the riches of web development packages, the Java programming environment and using an array of different media forms (e.g. video, voice, photos, etc.) the information system should be both supportive and motivating to an Engineer undertaking an appraisal. The web-based multimedia information system is expected to provide; 1. Broad and specific information on renovation issues; 2. Computer Aided Instruction (CAI) relating to formal building recording methods and techniques as prescribed by the Institute of Structural Engineers (IStructE); 3. A project management software tool aimed at carrying out structural appraisals based on the information and instructional facilities provided in (1) & (2). The web based multimedia information system will be designed using software design methodologies and tools such as; 1. The spiral software lifecycle development model. 2. Formal Object Oriented Analysis and Design methods (OOAD), using the Unified Modelling Language (UML); 3. Web-based development tools, such as MS Frontpage and JAVA, that support the implementation of the above software methodologies, multimedia data types and graphical user interfaces while providing hardware platform independence. STRUCTURAL APPRAISAL Structural Appraisal is a different activity to Structural Design insofar as it is aimed at assessing the real condition of an existing real structure. In appraisal the engineer is left face to face with an existing structure of definable qualities and must determine its condition and suitability of use. In defining a structures qualities an engineer can often gain from the experience of other engineers methods, available testing procedures and current developments in analytical techniques [IstructE, 1996]. However building appraisal is far from an exact science and more often than not engineering judgement will be called into play with regard to information obtained from the study of drawings and calculations, the results of surveys, inspections and possibly testing. Codes of practice are intended for use with present day materials and construction methods and these may therefore contain implicit or explicit assumptions that are not valid for the structure under consideration.

3 The Process of Building Appraisal. Building Appraisal is a process that usually encompasses the following; document research, inspection, measurements, recordings, and structural analysis. Although the approach to the appraisal of a simple structure and that for one of greater complexity will differ considerably, the flow diagram in Figure 1 below provides a comprehensive checklist or outline procedure. Establish Brief Investigate Safety Consider Access Undertake Initial Appraisal Carry out Desk-top Study Exploratory Investigations Review Brief Undertake Principal Investigation Analyse Data Figure 1. The Building Appraisal Process. Establish Cause of Problems Propose Remedial Work Consider Legal Matters Write Reports There exists a very broad range of professions involved in the building appraisal process, for instance, Structural Engineers, Conservationists, Fire Safety Engineers etc., each of whom offer a particular area of expertise necessary for a complete and thorough appraisal. The information system described in this paper will focus on the role of the Structural Engineer in building appraisal. The topic of building appraisal is so broad that a multimedia information system is an ideal way of communicating the subject matter, enabling the user to quickly focus on (via hyperlinks) their particular area of interest, within the vast store of information. Through careful planning and structuring of the information system, it is intended that the system will accommodate the needs of a range of users from, experienced engineers familiar with the system, through to novice engineers using the system for the first time. In order to produce such a quality information system, it needs to be developed in a systematic manner using proven software engineering methods and techniques. Such methods and techniques will be discussed throughout this paper. SOFTWARE DEVELOPMENT Having established the need for a MMIS for the building appraisal process, it is then necessary to apply proven Software Engineering methods in order to produce a quality product. Software Engineering involves the establishment and use of sound engineering principles in order to obtain software that is reliable and works efficiently on real machines [Pressman, 1997]. It achieves this through the use of methodologies, tools, and techniques to resolve the practical problems that arise in the construction, deployment, support and evolution of software [Institute for Information Technology, 1990].

4 With regard to the multimedia information system, such software engineering methodologies, tools and techniques are employed to promote systematic software development. An industry standard Software Life-Cycle (SLC) model, the spiral model, is used to ensure high quality software [Boehm, 1998]. Furthermore formal Object Oriented Analysis and Design (OOAD) methods, using the industry standard notation, the Unified Modelling Language (UML), will also contribute to producing extensible and maintainable software. These models and methods are discussed in the following sections. The Spiral Model of Software Development and Enhancement. The primary function of a SLC model is to determine the order of the stages involved in software development and evolution, and to establish the transition criteria for progressing from one stage to the next [Boehm, 1988]. The Spiral SLC model was chosen as the overall underlying model for the MMIS. This model promotes the principal of incrementality. Incrementality characterises a process that proceeds in a stepwise fashion, in increments. When applied to software, it means the desired application is produced as an outcome of an evolutionary process [Ghezzi, et al., 1991]. When an application is developed incrementally, intermediate stages may constitute prototypes of the end product. This essentially describes the basis of the Spiral SLC model (Figure 2). Figure 2. The Spiral Software Lifecycle Model. With regard to the development of the MMIS the spiral SLC model is ideally suited. The reason being that Engineers involved in building appraisal are generally unfamiliar with the use of the tools and technologies that are employed in the MMIS. As a result the Engineers are unsure of exactly what they would like the system to do or for that matter what the system is capable of doing. However it is hoped that on production of a prototype, some form of workshop / seminar can be arranged at which structural

5 engineers can test the software and give some constructive feedback. Then having developed the system in accordance with the spiral SLC model the feedback or suggestions given, could easily be incorporated into the system by an evolution of the original prototype. To successfully implement the Spiral SLC model requires adhering to proven software development methodologies. One such methodology known as the Unified Modelling Language (UML) [Fowler and Scott, 1999] was employed for the development of the MMIS, this is discussed in the following section. THE UNIFIED MODELLING LANGUAGE (UML) An object-oriented approach using the UML was employed in the development of the MMIS. The primary benefits of such an approach are that it leads to software that demonstrates the following qualities; Reliability, Robustness, Reparability, Evolvability, Maintainability, and Reusability [Ghezzi, et al., 1991]. All of the above qualities are of primary importance to the MMIS. There are three stages involved in the software development process; Analysis, Design and Implementation. Figure 3 depicts how the spiral SLC model underpins each of these three stages. SPIRAL SLC MODEL UML Use-Case UML Class Diagram ANALYSIS DESIGN IMPLEMENTATION Prototype Figure 3. Outline of MMIS Development Process. Development within each of these stages requires a methodology such as the Unified Modelling Language (UML). The Spiral SLC then provides us with a single framework within which we can progress cyclically through the stages of analysis, design and implementation, producing a succession of prototypes. As shown in the previous Figure 3 UML use-cases and UML class diagrams have been produced for the MMIS from the analysis and design stages respectively, these are best described as follows; Use-Cases - A scenario is a sequence of steps describing an interaction between a user and a system. A use-case, then is a set of scenarios tied together by a common user goal.

6 Class Diagrams - A class diagram describes the types of objects in the system and the various kinds of static relationships that exist among them. The UML itself is a complex modelling language and the use of a Computer Aided Software Engineering Tool (CASE Tool) is extremely beneficial when using the UML. The following section briefly discusses one such tool. Computer Aided Software Engineering Tools (CASE Tools). Using the UML is helped considerably by the use of Computer Aided Software Engineering tools (CASE tools). System Architect TM was used for the development of this information system. This CASE tool provides a graphic environment that supports UML. It can be used for creating diagrams, acts as a repository for model information storage, supports navigation through models, supports code generation for a variety of languages including Java and supports linking to databases (Figure 4). The benefit of this is that within a single environment you can proceed through each of the steps involved in the development of the MMIS, from analysis and design right through to implementation. Such an environment supports / promotes the spiral SLC model by allowing for a seamless and transparent progression through these various stages. The following section describes how System Architect TM was used to develop specifications and discusses the benefits of using MS Frontpage and Java to implement the MMIS. Figure 4. System Architect Screen Shot. SOFTWARE SPECIFICATIONS AND THE IMPLEMENTATION TOOLS In software engineering the term "specification" is used in several contexts with slightly different meanings. Wherever used the underlying theme behind the term "specification" is it states the requirements at some level for the implementation for a lower level.

7 The Uses of Specifications. The major uses of software specifications are: A statement of user needs, A statement of the requirements of the implementation, A reference point during product maintenance, [Ghezzi, et al., 1991]. The use-cases and class diagrams produced for the MMIS are a form of specification. The use-cases are a specification of the users needs. Ten use-cases were developed over three levels, each successive level dealing with a more specific /detailed use case. This is best illustrated by the following Figure 5. TOP LEVEL USE CASE User selects one of the Main menu options. General Overview Aspects or Areas of appraisal Reasons for carrying out appraisal Recording Environment General Overview section selected SECOND LEVEL USE CASE User selects a topic within the chosen option. Refer to Figure 1 for a summary of the topics that would appear in this section. THIRD LEVEL USE CASE User browses the chosen topic in Random Ordered A random or ordered manner. Remedial Works Initial Inspection Legal Matters Carry out tests. Analyse Data Cause of problems Figure 5. The Three Levels of Use Cases. Various details associated with each use-case (e.g. the steps involved in carrying it out, the preconditions, variations, etc.) are also documented with the use-case in a standardised template format. An example of this standard template is shown in the following Figure 6; LEVEL 1 USE-CASE 1 - General Overview Section Selected. CHARACTERISTIC INFORMATION. Goal in Context: User wishes to obtain a general overview 1 of the entire appraisal Process. Scope: Appraisal Process. Level: Summary. Preconditions: None. Success End Condition: User obtains sufficient information 2 easily 3.

8 Failed End Condition: User fails to obtain required information. Primary Actor: Engineer. Trigger: Overview option selected from main menu. MAIN SUCCESS SCENARIO. 1. User wishes to obtain a general overview of the appraisal process, hence selects that option from the main menu User browses through overview section in the order promoted 5 or suggested by the Information System. 3. Having gone through the overview section (use-case 6) the user is satisfied 6 with the information gained. 4. The user exits that section of the system. EXTENSIONS. 2a. User browses randomly through the Information System. 2b. User browses towards a specific area 7 of interest. 3a. Having gone through the overview section, the user is not satisfied with the information gained and exits the section back to the main menu. 3a1. User seeks more detailed information in the particular area of interest ( USE-CASE 3). RELATED INFORMATION. Priority: Top. Performance Target: Variable. Frequency: Unsure. Superordinate Use-Case: None. Subordinate Use-Case: Use-Case 6; going through an overview section, Use-Case 3; seek more detailed info. Channel to Primary Actor: Information System. Secondary Actors: Case Studies. Channel to Secondary Actors: Database. OPEN ISSUES. Will there definitely be a link from this section to the database of case studies, or will any case studies to hand just be incorporated within the information system. Figure 6. A UML Use Case. The benefits of using such a standardised format is that hidden details and risks are elicited by forcing the analyst/designer to consider each and every possibility associated with a given scenario. The class diagram associated with the above particular use-case is shown in the following Figure 7; The use-cases together with the associated class diagrams constitute a specification for the requirements of the implementation. Implementation Software Tools. The previously described work has resulted in a detailed specification of requirements for the MMIS. This section describes the software development tools that are currently being used to implement prototypes of the MMIS. Frontpage will provide the MMIS with a basic structure resulting in a web of static pages. Java applets produced in accordance with the previously described software methodologies will then be

9 incorporated to offer dynamics and the multimedia element to the information system. Furthermore its hoped that a recording environment will be offered by the MMIS. A prototype recording environment has been produced using MS Access, hence Frontpage's compatibility with such databases is also of primary importance. By applying the various software development guidelines discussed in this paper and using the various technologies described it is anticipated a MMIS that s effective, detailed and user friendly will be produced. Selected from Main Menu General Overview Section Offers link to + What is Structural Appraisal : class + Reasons for Carrying out a Structural Appraisal : class + Aims of a Structural Appraisal : class + Process of Structural Appraisal : class Offers link to persistent Reasons for Carrying Out a Structural Appraisal + Serious / Significant Deterioration : class + Defects in Design / Construction : class + Accidental Damage and Resulting Collapse : class + Proposed Change of Building Use : class + Building for Purchase / for Sale : class + Insurance / Legal Purposes : class What is Structural Appraisal + Very different to Structural Design : class + Becoming increasingly relevant in the Construction Industry : class + The Built Structure is not always the same as that designed : class persistent persistent Offers link to Process of Structural Appraisal + Establish Brief : class Offers link to Aims of a Structural Appraisal + To assess the real condition of a structure : class + To check / upgrade the structural fire protection : class + To check the ability to sustain increased loads / alterations : class + To check on any signs of distress, deterioration, fire or accidental damage : class + Investigate Safety : class + Consider Access : class + Undertake Initial Appraisal : class + Carry Out Desktop Study : class + Exploratory Investigations : class + Review Brief : class + Undertake Principal Investigation : class + Analyse Data : class + Establish Cause of Problems : class + Propose Remedial Work : class + Consider Legal Matters : class + Write Report : class persistent persistent Figure 7. A UML Class Diagram RESULTS AND CONCLUSIONS 1. Structural Appraisal is a very different activity to Structural Design insofar as it is aimed at assessing the real condition of an existing real structure. Unfortunately most Engineers are unaware as to the significance of this, with regard to how differently a structural appraisal needs to be approached by comparison to a structural design. A web compatible multimedia information system offers a good opportunity to rectify this shortcoming in most Engineers education. 2. Appraisals are commonly approached in a very unordered manner, there is a need to standardise, insofar as is possible, the procedure for carrying out a building appraisal. A multimedia information system (accessible from site via palm top technology)

10 acting as a project management tool offers a good environment from which to initiate such a standardising effort. 3. The topic of building appraisal is so reliant on visual inspection / observation that a multimedia software package is an ideal way of communicating the subject to the user. Furthermore since the topic is so broad, hyperlinks offer a convenient way for the user to focus on their particular area of interest within the vast store of information. 4. Systematic software development using a standard software industry development model, the spiral model, should be used to ensure that high quality software is produced. 5. Formal Object Oriented Analysis and Design (OOAD) methods, using the software industry standard notation, the Unified Modelling Language (UML), will also contribute to extensible and maintainable software being produced. 6. A recent construction industry forum agreed that construction professionals are increasingly turning to the Internet for technical and product information. Hyperlinks from the multimedia information system to manufacturer's and supplier's homepages could be an area for future development. 7. The information system considers building appraisal from the Structural / Conservation Engineers perspective, but it should also be of benefit to all those involved in the renovation industry (e.g. Architects, Local Authorities etc.) as well as anyone with a passing interest in the subject matter. REFERENCES 1. Whelton et al. (1998) The Systematic Development of an Integrated Information System for the Structural / Conservation Engineer MEngSc thesis, National University of Ireland Cork, Ireland. 2. Holland, R., Montgomery-Smith. B.E and Moore J.F.A. (1992) Appraisal and Repair of Building Structures, Introductory Guide, Thomas Telford, London. 3. The Institution of Structural Engineers (IstructE)(1996) Appraisal of existing structures 2nd Edition, London:IStructE. 4. NATO Science Committee Conference (1969) (quoted by Pressman, R.S.(1997) Software Engineering: A Practitioner's Approach), 5. Institute for Information Technology, NRC Canada (1990) Boehm, B.W. (1988), A Spiral Model of Software Development and Enhancement, TRW Defense Systems Group, Computer 21(5), pp Ghezzi, et al., (1991) Fundamentals of Software Engineering, Prentice-Hall, pp Fowler M. and Scott K. (1999) UML Distilled 2nd Edition, The Addison-Wesley Object Technology Series.