Application of business process modelling approach for FRP bridge management Yaseen Srewil, Institut für Bauinformatik, TU-Dresden
[email protected]
Abstract: The recent advances in polymer-based components for construction applications lead to additional opportunities for replacing conventional structural forms with fibre-reinforced composite components. Although fibre-reinforced polymers (FRP) have favorable characteristics that make FRP composite very competitive, these materials have not yet been exploited. The initial costs of components and complex manufacturing processes for composite components in construction are delaying the extended application of FRP. Manufacturing is currently based on inefficient manual on-site processes. To increase the degree of industrialisation of the construction process of FRP components a comprehensive process analysis and reengineering is required. This work presents the use of business process modelling techniques to provide the flexibility and adaptability for creation and administration of process patterns in systematic reuse and adaptation. Conceptual model based on flowcharts of bridge components on-site installation is defined. Mapping from conceptual model to business process modelling notation (BPMN) presented to support the customisation of the process model according to the certain project and site contexts and constraints.
1 Introduction Fiber reinforced polymer composite (FRP) developed essentially for the aerospace industries. The favorable characteristics of FRP components lead to the use of these components in various engineering applications (aerospace industry and automobile industry) (Hong & Hastak, 2007). However, FRP composite has become popular in recent years especially in construction of new facilities and in renewable of existing structures in super- and infrastructure. It presents many technical advantages and economic benefits over traditional materials. A great potential application of fiber reinforced polymer is bridge construction. The favorable characteristics makes FRP composite a very competitive as bridge components, namely the high strength to weight ratio, lower self weight, the electromagnetic transparency, flexible to form with any cross-section geometry, the easier installation, the lower maintenance requirements and the improve durability under aggressive environments (O’connor & Hooks, 2003). Therefore, new generation bridges are projected to utilize higher strengths and engineered materials that would result in aesthetically appealing slender bridge structures, and more enduring. Although, fiber-reinforced polymers FRP exhibit advantageous material properties the potential capacity of these materials have not yet been exploited. One of the factors that are delaying the widespread usage of FRP composite in bridge construction as structural elements is the complex manufacturing processes for composite components in construction and the lack of comprehensive modelling of construction. Manufacturing is currently based on inefficient manual onsite processes. Thus, the execution of these tasks is strongly related to the human
experience. Consequently, the error-rate within the construction processes is relatively high. To increase the degree of industrialisation of the construction process of FRP components and the speed of erection a comprehensive process analysis and reengineering is required. This work presents the use of business process modelling techniques to provide the flexibility and adaptability for creation and administration of process patterns in systematic reuse and adaptation. Conceptual model based on flowchart of bridge components on-site installation is defined. Mapping from conceptual model to business process modelling notation (BPMN) presented to support the customisation of the process model according to the certain project and site contexts and constraints. In June 2009 The European Trans-IND1 project has been launched. Two academic and eighteen industry partners in duration of 4 years were involved to deal with the industrialisation of processes for building bridges with FRP-components. The TransIND overall objective develop a cost-effective integrated construction process that will enable the maximum capability of industrialisation of components to transport infrastructures (road and pedestrian bridges, underpass, containing walls, acoustic and safety barriers) using polymer based materials.
2 FRP Bridge system Vehicular bridge is the best choice for FRP composite application. FRP bridge system herein could have a span between (15-30 m) and simple supporting beams. FRP bridge components are typically Deck, Beams, Joints and bridge accessories (secondary elements). These form the superstructure and deck of bridge, the breakdown of the bridge structure is illustrated in figure 1. The substructure bridge components (Piers, Abutments and footings) are typically made of reinforced concrete. Infrastructure
Road & Highway
FRP Bridges
Joint
Deck
Traditional Bridges
Beam
Secondary element
Figure 1: The breakdown structure of FRP Bridge The following is the definition of FRP bridge elements:
1
Trans-IND: http://trans-ind.eu/
Pier
- FRP Deck: (sandwich panels, Multi –cellular panels, etc.) FRP composite bridge decks deliver viable solutions to meet critical needs for rehabilitation of existing bridges (replacing the existing deck) and construction of new bridges. It can be manufactured as one piece construction or shipped in separate panels with minimal assembly on-site (MDA, 2004). - FRP Beam: (Platforms, supporting structures, I-profile, C-profile, L-profile, etc.) structural profile is used mainly as simple beams, also used in simple form or interconnected configuration (Top Glass). - Joint: conventional shear studs/ stirrups. It’s function is as a deck-to-girder connection. - Substructure elements (Piers, Abutments, footings, etc): typically in vehicular bridges is reinforced concrete, steel or masonry. - Secondary elements (bridge accessories; Curbs, waterproof layer, drainage system, etc.) Figure 2 shows the target FRP bridge system with main FRP components (deck panels, joints and beams).
Figure 2: FRP Bridge system (Trans-IND Bridge system)
3 Business process modelling in FRP Bridge management Business Process Modelling “BPM” can be defined as the human activity of creating business process models. A business process is a specific order of tasks, determined by the set of project conditions, across time and place to achieve a determined subproduct in the project. In turn each sub-product represents the end state of a process and a start state for one or more other processes. A business process model is the result of mapping the current (as is) or a future (to be) state of an organization’s business process (Sharmak & Scherer, 2009). In the BPM domain there are many modelling techniques such as: Business Process Modelling Notation “BPMN” and Event driven Process Chains “EPCs”, which suit different requirements of the organization in different management levels. These process techniques are based on a specific modelling method, meta-model, which provides guidelines for the construction of process models. Depending on the intended goal of representation form, other
elements of interest besides activities and logical dependencies can be represented in a process model (Curtis et al, 1992). In this work, Business Process Modelling Notation “BPMN” is used as a process modelling technique to represent the process model of FRP Bridge installation (OMG, 2009).
3.1 Conceptual model of installation FRP Bridge components The design of process model of FRP Bridge is partly the mapping of a process structure given in reality for installation procedure made by Matin Marietta composite (MMC, 2005, Hastak et al, 2004) as well as the subjective interpretation of the real world and the mental construction out of a world of experience. Hence, the process model of FRP Bridge can be a potential solution of how things could be done in the future. In order to model the construction processes of FRP bridges the following procedures are required (Hastak et al, 2004): - Identify work tasks in the processes (fundamental field action and work unit focus, intrinsic knowledge and skills at a crew member level, and a basis of work assignment to labor) - Identify Resources (equipments, materials, manpower, etc) - Identify the logic of processing of resources, - Build a model of the process. The installation procedure of FRP bridge components varies and depends on the manufacturers. The on-site installation methods have the larger proportion of the cost of the bridge as opposed to material and fabrication cost (e.g. FRP railway bridges) (Canning & Speight, 2009). The installation procedures flowchart of FRP bridge herein, which is illustrated in the figure 3, represents the different installation phases and the interaction with the delivery components out of the construction site. It comprises the transportation of FRP components from manufacturing site activities and installation of the bridge components at the work site. The procedure’s flowchart characterizes the process that is a necessary step to process modelling. Within the flowchart is considered one segment of bridge which is in this case representing one span between two simple supporting beams. Based upon this consideration the installation process of the whole bridge is composed of portions of recurring processes. The installation process takes place afterward the composite components shipped from the manufacture to site work. First phase is the installation of FRP beams on existing concrete abutments or piers. This phase is a constraint to the second phase in a segment of bridges. The second phase is to install FRP deck panels to the beams with suitable joint and grouting this joint with appropriate material such as polymer concrete. The delivery process of FRP components is a constraint for the both installation phases. The following illustration shows the procedures from the perspective of transportation and on-site work:
Transportation from manufacturing to work-site Phase I: Beams installation
Composite elements (Beam-ID, Panel_ID, etc) to be loaded
Phase II: Deck Panels Installation
Composite Beam unloading, (Beam_ID)
FRP Elements unloading, (Panel_ID)
1st. Composite beam (Beam_ID) Installation & Alignements
First FRP element (Panel_ID) Installation & alignment to the beams
Composite elements transport to the „Job Site“
i+1
Material Requisite of „FRP Components“
Logistics
Actvities at work-site
Stability of composite beam (Beam_ID) utility of Temporary secure element
Stability of FRP element (Panel_ID) & securement
i+1
Management
Installation of (i )FRP element (panel_ID) to the Beam Installation of (i ) element (Beam_ID) to the pier Jointing work: (i) element (Panel_ID) to (i+1) element (Panel_ID) Finished Beam installation Activity
Grouting works Workflow Message
Finished Panel Installation
Figure 3: FRP Bridge procedures flowchart (components transportation, beams and deck panels on-site installation) Transportation and logistics procedures: - Loading the FRP components from manufacturing site to flat trucks - Transport the FRP components to the work site. Installation procedures on-site can be divided in two phases: Phase I: FRP beams elements installation: - Beams are unloaded at the work site by movable crane - The First beam is installed to the existing bridge piers or abutments using movable crane and aligned using a crane. - The second step is repeated until all beams have been installed. Phase II: FRP panels installation: - Panels are unloaded at the construction site using a jack or movable crane from the flat bed truck. - The first panel is installed on top of the beam using a crane and aligned using a jack. - Repeat the second step until all panels have been installed.
- Jointing works (panel to panel) - Connect the deck to the girder (panel to beam), shear studs are field-welded and grout is poured into cavity. Figure 4 contains the necessary information for the construction process, including the name of the activity, component (referred to by the activity), the predecessor and successor activity and the necessary materials, machinery and labor and their productivity, including the amounts or performance factors. The description of each individual process activity explains that activity in detail. Standard manual template of textual description and list of activity data can be used to describe the activity, purpose of the task, inputs and outputs associated with the activity, typical duration of the activity. The input and output of each activity details the information flowing. Therefore, each activity is part of a chain of tasks; information resulting from predecessor activity is often required to undertake the task and/or the current activity results in the production of new or updated information to facilitate the next activity (Harvey & Owens, 2008). Proceding Activity: (Beam_ID unloading) Equipment: Movable Crane Performance factor
Performance factor
Activity: Beam_ID installation
Material Delivery: Beam_ID Specification, quantity, Size, etc.
Labor Resource: Joints works
Succeeding activity: Beam_ID Stability & Securement
Figure 4: An activity connect to predecessor and successor activity and the appropriate resources in the workflow chain
3.2 Business process modelling notation (BPMN) The Business Process Modelling Notation (BPMN) specification provides a graphical notation for expressing business processes in a Business Process Diagram (BPD). The objective of BPMN is to support business process management by both technical users and business users by providing a notation that is intuitive to business users yet able to represent complex process semantics. BPMN as a modelling technique provides an easily understood graphical notation that could serve as a front end to various approaches for the execution of business processes. The language itself is not intended to be directly executable; rather specifications are expected to be transformed to an executable language to achieve their enactment (OMG, 2009). The main purpose of BPMN models is to facilitate communication between domain analysts and to support decision-making based on techniques such as cost analysis, scenario analysis, and simulation (Recker et al, 2005).
The basic element of the BPMN modelling is the Task which represents a single process step and is symbolized by a rounded rectangle. The order of Tasks is described by the Sequence Flow, a simple solid arrow. In order to assign the Tasks to their operator or the process owner so-called Pools are defined which can be further divided into Lanes. A Pool would be, for example, a company whereas the Lanes represent different departments. The Tasks of different pools, however, are not connected by a Sequence Flow, but communicate over information flows. Besides the previously mentioned flow objects exists the so called artifacts (Data Objects, Groups and Annotations) that do not affect the Sequence Flow or Message Flow of the Process directly, but provide information in any form. The most important ones are the Data Objects that assign documents, data, and other objects via undirected Associations or classify resources as an input or output of a task using directed Associations. For branching process flows Gateways are used to split up and merge the Sequence Flow. These Gateways serve as logical connectors. The basic forms are the Inclusive, Exclusive and the Parallel Gateway. The core modelling elements of BPMN are illustrated in figure 5.
Parallel, AND
OR
Start End
Connecting Objects Task Collapsed Sub-Process
Sequence Flow Association Message flow
Timer
Swimlanes Name
Exclusive
Activity
Name
Event
Artifacts Pool
Name Name
Gateway
Lane
Data Objects
Annotations
Message
Figure 5: Elements and Notation of BPMN
3.3 Process model of installation FRP bridge in BPMN An extract of an example of the process model for one segment of FRP bridge is given in figure 6. This prototype model is based on the installation procedure flowchart that introduced in figure 3. This model shows the hierarchical use of combination of process model for FRP components installation based on BPMN (OMG, 2009), delivery (logistic) model of FRP components from the manufacture site to the construction site and the appropriate resources for each sub-process. It represents an abstractive view of FRP installation process. Each sub-process represents a collection of activities (and gateways and flows) being represented collectively as a single activity. Starting with the sub-process of FRP beams delivery that attached to the logistic model lane and the output is the delivery of FRP bridge components. In FRP process model lane the beams installation on-site sub-process is trigged when the deliverable materials have been arrived to the job site. On the other hand the deck panels installation sub-process starts directly after all beams in one segment of bridge have been installed. Meanwhile, the deck panels for this segment arrived at the job site that represented in AND-join gateway (figure 6). AND-join merged two threads into one thread. It is a synchronization point – it waits for both threads to complete.
The resource container, attached to a resource lane, provides the appropriate resource for the erection activity (machine, labor and material as introduced in figure 4). The management connected to separate swimming pool and swim lane, with a simple, twostep process to organize all processes on the other pool. The output of the delivery order processes is the delivery schedules whereas it is input data to the logistic model. This suggested approach is flexible and allows the sequences delivery of FRP components according to the site conditions and its possibilities. The intermediate timer event within the sequence flow of material orders (in the management pool) and FRP components delivery processes (in the logistic model) indicate that the process will wait for fixed date or fixed amount of time (hours, days, weeks, etc.). Hence, the components can be requisite in one order then all FRP components (beams, deckpanels) will be delivered parallel according to the delivery plan. On the other hand the delivery process of deck panels can be delay for (x) days according to the actual works on-site for each bridge segment (i.e. FRP beams delivered firstly and installed while the FRP deck components arrive). Accordingly, the whole installation of the FRP bridge segments is portions of recurring of this suggested model. Finally this model represents the top level of logical order of the installation process and delivery process of the bridge components and their constraints.
Figure 6: Process model of delivery and installation procedures of a segment of FRP bridge components
4 Summary and future work The various components of FRP bridges are presented in this paper. Moreover, the relationships between the installation phases and shipping out of construction site are described. This work has discussed the innovation of using composite-based materials in bridge construction and the possibility of modelling the installation process and the interaction between the installation model and logistic model with assigned recourses. Furthermore, process model based on BPMN was built to represent the actual
installation procedures on-site and the delivery model out of construction site for FRP bridge components. The future works have to consider the accelerated delivery and erection of bridge components and develop a solution for efficient and reliable delivery of prefabricated components, controllable with easy identification such as using RFID technology (Radio Frequently Identification).
5 Acknowledgements The Trans-IND project is European funded project.
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