Computing in Civil Engineering (2007)

In this research, we present an optimization heuristic to solve the horizontal alignment of a highway segment. The iterative heuristic works in two stages. The first stage uses a neighborhood search approach to find a good piecewise linear line that approximates the highway alignment. The second stage further adjusts the alignment so that the external and code requirements are accurately satisfied. Both stages manipulate the piecewise linear line with a neighborhood search heuristic, and use a mixed integer program (MIP) to ensure that the piecewise linear line crosses the control areas and avoids the restricted ones. The optimal objective function value returned by the MIP is used to compare the quality between different piecewise linear lines. The lengths of each line segment are properly constrained in the MIP to ensure that curves can be correctly deployed. Starting from an initial feasible solution the process gradually improves the alignment through iterations.

Scheduling is among the most important managerial functions for constructions projects. The traditional critical path method has conceptual shortcomings that limit its analytical depth. These issues are overcome by the linear scheduling method. Linear schedules are ideally suited for any project featuring one predominant dimension beyond time, whether geometric or repetitive. Temporal and spatial constraints can be applied and interferences can be identified. Implementation of linear schedules in practice is very limited due to the lack of a full analysis methodology akin to the critical path method. Previous studies limited themselves to only assuming sample activities with constant productivities. This paper introduces a new analytical method for linear schedules that uses singularity functions to describe all activities and their interrelationships. These functions are computationally desirable due to several advantageous mathematical properties. An example of a transportation project demonstrates the application of the new method. Possible future extensions are briefly noted.

Hourly equipment cost rates are vital to the long-term profitability of a company. Hourly rates are based on the forecasted owning and operating costs. The residual value is the most elusive element of owning and operating costs. It differs from book value, which is typically calculated for taxation purposes using a depreciation model. The residual value of heavy construction equipment is defined as the monetary value that can be anticipated to be actually realized in an open market transaction. Forecasting it statistically allows for an integrated cost model for heavy construction equipment. A comprehensive study of auction records for various equipment types, makes, and sizes resulted in a statistical model of residual value. Quality of the model was ensured through hypothesis testing and coefficient validation. Residual value grids are intuitive graphical tools used to present the underlying datasets and quickly and accurately forecast residual value with reliability.

Over the course of a typical project, construction managers must interpret a great volume and variety of ever-changing project control data. Due to the volume of data, issues related to schedule, cost, resources or design intent are often overlooked, thereby resulting in the failure of judicious handling of important situations at any given point in time. We propose to use visual representations to clarify the complicated structure of data, eliminate confusing factors, and identify key elements. Several research efforts have been conducted to cope with the lack of visual representations in the construction management domain. However, most of these efforts have focused on visualizing either spatial building structures, sequence of construction activities, or construction operations. There has been little research efforts focused on information visualization in construction management. As a result, the construction management community is still faced with the problem of how to digest vast amounts of data and understand its complex intricacies in the dynamic and fragmented environment of construction; where data have a number of formats and are communicated through a variety of medium, which increases the potential of a communication breakdown among project team members. Some of the fundamental research challenges to be addressed in visualization of project control data include finding answers to several critical questions. This paper proposes a research agenda to the construction management community to encourage research in a variety of areas related to visualization of project control data.

Using highway-bidding data from Texas highway projects several different ratios were calculated to describe relationships between the submitted bids such as the spread of the submitted bid and the difference between the low bid and the second lowest bid. Elevated levels of these ratios have been found to be associated with projects that have significant deviations between the original low bid amount and the completed project cost. The Ripple Down Rule (Ridor) classification algorithm was used to generate a set of rules from the database of bidding ratios that provides a prediction of the expected level of cost increase over the initial low bid price. The classification rules generated by the Ridor algorithm are presented. A test set was used to determine the usefulness of the generated rules in predicting project cost increases and results of the testing are presented.

Recent world events involving chemical and biological (CB) attacks within critical infrastructure have highlighted a potential threat to buildings and their occupants. As a result, protecting buildings from CB attacks has become an important design consideration. A collaborative research effort is underway to develop a design assessment system that will provide decision makers the ability to compare multiple building designs for protection against an internal CB release. The assessment system includes modeling and simulation of CB contaminant dispersion, a quantitative financial method to compare design costs, and a multicriteria decision making phase. This paper outlines the design assessment system phases, and focuses on the computational details for assessing building CB exposure using multizone and spreadsheet programs. A hospital emergency room is used as an illustrative example. The concept of fraction of building protected (FBP) is explained, and the cost percent increases associated with 15 redesign options are presented.

Group Method of Data Handling (GMDH), was proposed by Ivakhnenko in 1967, is based on the principles of heuristic self-organization that is developed to solve complex problems with large dimensionality, such as pavement maintenance and rehabilitation (M&R) decisions. In the paper, an empirical study is conducted to develop M&R decision model by using GMDH. Pavement distress surveys were performed on seven county roads by experienced pavement engineers of Taiwan Highway Bureau (THB). For each road section, the severity and coverage of existing distresses and required M&R treatment were separately recorded. The analytical database consisting of 2,348 records (2,115 records for model development and 233 records for model testing) are established to develop and test the M&R decision model. The finding shows that the total accuracy of proposed model is 0.940 based on the testing records. It illustrates that the GMDH-based M&R decision model certainly can make pavement knowledge extraction systematically, successful, and easy-to-use even for the complex M&R decision problems.

Recent efforts of National Institute of Building Science (NIBS) members have moved the goal of interoperable, life-cycle exchange of building information closer to fruition in the United States. This has been accomplished through the specification of individual information exchange packages, based on the requirements of well defined business processes, using the Industry Foundation Class (IFC) model. There are many opportunities for direct participation in the development of the National Building Information Model Standard (NBIMS).

This paper presents a multiple case study on building design process with the implementation of IT tools (project extranet, two- and three-dimensional modeling and physical interference analysis system). It aims to investigate 3D harmonization design process and information and communication management during the building design process. The use of a web environment facilitated the communication of the technical teams, improving the information flow among them with the optimization of the entire project development. The management planning tasks involved action and communication plans development. The action plans were helpful for task workflows and schedules definition, timing for hiring teams, team members' training, certification and responsibilities. Moreover, they were crucial to the integration of the different design disciplines in order to minimize interferences and improve the harmonization of the whole building design. The communication plan proved to be crucial in maintaining the teams' dynamics as a whole, and the information flow for the entire process.

Transportation infrastructure asset management efforts normally focus on collecting data on items with low volumes and higher capital costs, such as bridges. Road signs and pavement markings, on the other hand, are high volume, low capital cost items but are critical elements of the transportation infrastructure. These high volume assets serve a critical function, safety, and thus they are receiving attention. In particular, the Federal Highway Administration (FHWA) has been working to establish minimum retroreflectivity standards for signs and pavement markings. This paper seeks to address information technology (IT) problems that emerge when developing an overall asset management system for high volume assets and to identify their unique characteristics. These IT problems include asset identification, asset location, data availability, data fragmentation, automated data collection, software selection, and system size and resources. A discussion of the issues related to these problems is presented herein to facilitate the development of more comprehensive systems to manage the automation of infrastructure asset management systems (AMS).

Several mathematical models have been developed for cost optimization in repetitive projects. These models aim at defining the optimum output rate for each repetitive activity that yields the minimum overall cost of the project. However, all these models assume that there is only one logical sequence of the activities in a project while in the real-world projects, the logic between activities can be divided into fixed logic and soft logic. The fixed logic provides only a logic sequence of the construction activities. On the other hand, soft logic provides other possibilities of analyzing the activities. When faced with a project involving many repetitive activities with soft logics, the more NAOT (Number of working units which a repetitive Activity can precede at One Time) provided for each repetitive activities, the less project duration may be but the more project cost is required. Similar to traditional time-cost trade-off problems, the challenging question confronting the planner will be more than the optimum output rate for each repetitive activity that yields the minimum overall cost, but also which is the optimum NAOT for each repetitive activity that yields the minimum overall cost. This paper applies dynamic programming and presents a new formulation with consideration of soft logics defining the optimum output rate as well as NAOT for each repetitive activity that yields the minimum overall cost.

The advancement of information technology has resulted in the development of new visualization and planning tools that offer major improvements when compared to the use of traditional planning tools such as Gantt charts and Critical Path Method. Despite their limited capability for planning and monitoring projects, these tools are still almost universally used by the construction industry. Two case studies managed using traditional techniques, one construction of an apartment block and other installation of a new high technology production facility in the Precast Concrete Industry have been reviewed in the paper from a viewpoint of how the application of new 4D (3D+time) and visual planning/simulation techniques would have improved the management and control of the projects. Widespread use of visualization and simulation techniques in the Aerospace and Car Industries is compared with the limited use in the Construction Industry. The paper examines the barriers to the introduction of the technology based on the experience gained from the presentation and demonstration of the visualization technology to six major construction companies operating in the UK construction industry and the means of breaking down the barriers to the implementation of the new IT innovation are discussed.

In a current research project, our group is developing a 3D Spatial Query Language for Building Information Models. Among other features, the spatial language includes metric operators, i.e. operators that depend on the distance between 3D spatial objects. To implement these operators, a fast and well-scaling algorithm based on the octree-encoded discretized geometry for computing the distance between two polyhedra was developed. The proposed algorithm implements a divide-and-conquer strategy: It uses comparably cheap polygon-octant intersection tests to build up the octree, and subsequently performs very simple distance calculations between two octants, that can be realized as fast integer operations. The paper describes the algorithm in detail, discusses its scaling behavior and the advantages of using an octree encoding.

Artificial Intelligence (AI) has a long history in computer science and is now being applied to engineering problems in Structural Health Monitoring (SHM) that would be difficult to solve by standard numerical techniques alone. In particular, the methods of Conventional Artificial Intelligence (CAI) and Computational Intelligence (CI), coupled with agent technology, show great promise in delivering monitoring systems that are robust, redundant, environmentally aware, economically sound as well as user friendly and highly adaptive. In this paper, background concepts of AI and an example of a SHM system for monitoring civil engineering structures are presented to clearly demonstrate the potential of intelligent software applications in the field of SHM.

Current construction practice usually provides a variety of different execution alternatives for each project objective. Normally, only one possible construction schedule is selected and defined manually. Thus, decisions are often narrowed down and made at a stage where this cannot be done in a reliable way. Often it seems useful, if more than one alternative solution could be investigated. However, modeling solution alternatives is very tedious and not supported by standard solution approaches. This paper presents an approach for generating a construction schedule that includes various alternatives within a single model as well as provisions for reuse of former project experiences. The schedule can be generated on the basis of independent construction tasks. Associated constraints are formally described by the use of Feature Logic theory. Thus, a schedule can be generated automatically at any time in the process. This should lead to a higher flexibility and application of well proved solutions to problems that might occur on construction sites. In such cases, a faster reaction can be achieved by responding with predefined, tested alternatives. For practical reasons the reuse of already predefined solutions is extremely significant. Therefore, the application of case-based reasoning has been investigated for the purposes of this work. Partial construction solutions can be stored, retrieved and re-used using a case-based system.

During the building life cycle continuously data regarding the building is produced and collected by various disciplines. Especially in early phases of design concept development information needs may occur, which require manual information seeking within the collected data. The availability of user interfaces which allow visual navigation within an integrated view to the distributed data as well as the usage of parallel searching strategies would help a planner to go through several alternative solutions very quickly. Based on a shared conceptualization explicitly represented in a shared ontology the information physically spread among several partial models can be integrated into a global view. Great efforts have already been made in defining shared conceptualizations for the AEC/FM sector which can serve as an integration basis. Utilizing the software agent technology along with concepts evolved within the Open Hypermedia research an open "engineer-friendly" information seeking environment can be established on top of an ontology-based integrated view. This paper examines several related research work and describes an overall system concept of such a navigation layer.

Knowledge management (KM) is the organization, creation, sharing and flow of knowledge within organizations. The knowledge can be reused and shared among the involved engineers and experts to improve the construction process and reduce the time and cost of solving problems. This paper proposes a new and practical methodology to capture and represent construction project knowledge by using network knowledge maps approach. Using Knowledge Maps, users can get an overview of available and missing knowledge in core project areas and take appropriate management in tacit and explicit knowledge. This study addresses application of knowledge management in the construction phase of construction projects and proposes a Construction Map-based Community of Practice system (MbCoPs) for contractors. The MbCoPs is then applied in selected cases study of a construction bridge project in Taiwan to verify our proposed methodology and demonstrate the effectiveness of sharing knowledge special in the construction phase. By developing communities of practice system, all participants in the project can share explicit and tacit knowledge according to the interesting topic through the web-based platform anytime and anywhere. The combined results demonstrate that, an MbCoPs-like system can be an effective tool for construction knowledge managements in construction industries by utilizing the map -based knowledge approach and web technology.

State highway agencies must strive to set accurate and reasonable contract performance times in order to encourage qualified bidders, produce quality projects, and minimize impacts to the traveling public. The Federal Highway Administration recognizes this and has mandated that all state highway agencies have an approved, written contract time estimating procedure. The Federal Highway Administration also published a number of recommendations to assist individual state highway agencies in meeting this mandate. Among these recommendations is the development of a database of historical production rates and adjustment of these production rates for unique project characteristics. This work describes the development of a bid item level performance time database management system known as BIDDS. Primarily, BIDDS can be used by the scheduler, in conjunction with individual engineering judgment, to establish construction activity production rates. These rates, along with known material quantities, can be used to derive construction activity durations for the development of the pre-advertisement schedule.

Current Building Information Models (BIM) are more complex than typically required for the early phase of the design process of a building. Reasoning with all the detailed components in a BIM intended for construction requires unnecessary effort. Therefore, this research developed a light-weight knowledge representation of a building for automatic reasoning about the conceptual design process. This research utilized an ontology to provide an underlying structure of objects and relationships of a building. The knowledge representation model developed was mapped to the IFCs (Industry Foundation Classes) data model for an open, global ISO standard that integrates information and data on construction projects and enables building information to be shared among the participants. A case study was conducted to develop a structured representation of an ontology where the relationships among the necessary components in the stage of preliminary design were to be automatically utilized to plan on the sizes of each room in a building and structured thoroughly with a simple structured representation.

The dynamics of the excavation process affect the performance of resources involved in the operations. This is significant for the reasons: (1) most of excavation work requires costly resources such as excavators and trucks; (2) the overall performance of the process depends on the performance of such resources; and (3) there are intricate interdependencies among resources. In order to incorporate analysis of such dynamics in managing excavation operations, an approach based on dynamic process modeling and simulation is presented. This approach provides critical operational information for effective planning and control of the process, including the progress and corresponding schedule of the overall process and the efficiency of individual resources over time and at the completion that can be used to find a balanced combination of resources. To demonstrate the usefulness of the proposed approach focusing on excavation in building construction an application example is presented.

This paper discusses the development of a machine-readable language representing the principles of building design. Building design is a complex process taking into account many different factors and variables, such as the function, site context, environment, materials, cost, culture, etc. The focus of this work is to develop an ontology describing the principles for building design and relationships among them. The methodology for the creation of an architectural ontology is discussed, as well as the tools used to construct and link concepts, attributes and relations. The architectural ontology could be used in software applications for automated design, where design parameters are prescribed. In that sense, information about the site, physical systems, building orientation, materials and other constraints can be prescribed by the user. This paper discusses the applications of an ontology for tall building design, since tall structures impose special problems due to the scale and complexity.

This paper describes two prototype systems that simulate asset management decisions for a network of pavement segments in terms of usage, maintenance and improvement decisions implemented, and deterioration. One prototype is developed in MATLAB; the other in Repast. The prototypes reflect expected system behavior; however, capturing realistic human behavior is challenging. These prototypes suggest the potential of agent-based modeling for improving infrastructure management.

Increasing congestion and air quality problems have led agencies in urban areas to implement mass transit systems to improve mobility, safety, and quality of life. These transit systems cause significant delays to vehicular traffic at railroad crossings. Literature documents limited research on modeling railroad crossings. With increasing emphasis on transit systems, there is a need to develop models to simulate and evaluate railroad crossings to maximize the derived benefits and reduce the impact of mass transit systems on other modes of transportation. The main objective of this paper is to evaluate and compare the features available in commercial traffic simulation software programs such as Synchro and VISSIM and to simulate railroad crossings. Data collected at a study location during peak and off-peak hours are used to evaluate the capabilities of Synchro and VISSIM traffic simulation software programs in simulating existing conditions. The number of stops and maximum queue lengths are collected to validate the effectiveness of these traffic simulation software programs. Results from such evaluations serve as necessary inputs for decision makers to identify potential solutions to improve operational performance of railroad crossings. Recommendations based on factors such as system requirements, data requirements, need for calibration, ease of use, accuracy of performance measures reported in the output, and their versatility are discussed.

The increasing use of equipment management information systems has greatly simplified the construction equipment management for large contractors. Recent developments in data mining techniques make it possible to embed data mining functions into the current information technology (IT) environment to serve as knowledge discovery and decision support modules with a significantly reduced development cycle. This paper proposes a general framework for the building of knowledge-driven applications for construction equipment management with integrated data mining. The research is expected to enrich and enhance the current decision support system for construction equipment management through data mining based knowledge acquisition and utilization.

Construction operations include many complex tasks and dependencies among resources. Traditionally, collecting operational data involves several manual steps to convert time-lapse photos or videos into productivity data. These manual steps are time-consuming, labor-intensive, and prone to errors. Several technology advances have made new approaches possible for data collection and analysis. Many researchers have experimented with Global Positioning System (GPS) and Radio Frequency Identification (RFID) technology to track the resources on site. By integrating pre-specified boundaries which are associated with the site layout or activities, engineers are able to track the current status of the resources or the current activity in which these resources are engaged. However, these positioning data can be further manipulated to provide more detailed information regarding construction operations such as resource bottlenecks, utilization, and balance. This paper presents an on-going research that analyzes the dynamic geometrical data of resources to extract construction operational information. Preliminary results are presented to demonstrate the feasibility of automatically converting real-time positional data of tracked resources once the geometrical patterns (operational model and strategies) have been identified. A conversion model representing the geometrical patterns is used to transform the input, the positioning data ObjectID(x, y, z, time) collected from RFID or GPS at regular time intervals, into information for productivity analyses. A case study of concrete drainage pipe installation is used to verify and validate the concept. Further discussion will be presented on precisions, lessons learned, and limitations of the relevant technologies.

Numerous interrelated factors affect building performance. Physical building elements, internal and external climatic conditions, and building occupants interact through time to impact the way a building consumes resources. Currently, however, leading building performance software programs represent much of the information related to these factors in text or chart form. Such representations make it difficult for building designers, operators, and other stakeholders to understand how this information interacts through time. This paper describes an early prototype called OViz, which creates spatio-temporal representations of (observed and/or assumed) geometry, occupancy, environmental, and performance data, and enables users to visualize and explore how this information changes through time in a 3D environment. We are testing the extent to which these visualizations help designers and operators understand and detect meaningful patterns and interrelationships amongst the information and whether they can support design and operations decisions.

For a successful construction project, as-built progress should be constantly monitored and compared with the as-planned construction progress and real-time corrective actions should be taken in case of observed discrepancies. Current media representing these discrepancies (e.g. charts, graphs and still photos) may not facilitate the communication of progress information clearly and quickly which makes the process time-consuming and distracts decision makers from important task of corrective decision making. A series of conceptual visualization techniques (e.g. augmented reality, color and color gradient) have been recently developed to facilitate the communication of progress information and decision making on corrective actions. In this paper, several semi-automated vision-based approaches are applied to further improve and facilitate these processes. To that end, camera matching and registration of the as-planned model with as-built photograph, analyzing the progress status through a material-based detection technique and generation of an occlusion-free photograph are presented.

One of the major aims in computer-aided engineering is to assist the planners in communication and collaboration during the building planning process. Since model-based planning is becoming widely accepted in the building industry, we assume that planners are working on partial models stored in distributed and heterogeneous model databases. A main goal of this project is to provide the engineers with an integrated view on these heterogeneous models. To realize this, two levels of integration have to be considered: the access level integration and the semantic level integration. In the presented project, the problem of access level integration is approached by software agents. However, in this context the core problem is the inconsistent semantics of the heterogeneous building model. Thus, this paper focuses on the semantic level integration. Based on an analysis of different types of heterogeneity a method for semantic integration of building model data in civil engineering is presented on the example of fire protection engineering. To provide fire protection engineers with an integrated transparent view, an ontology-based approach has been developed. The problems of distribution and heterogeneity are approached by different solution layers, following the principle of separation of concerns. By those means, the integration effort can be reduced effectively and resources can be integrated flexibly into network-based building project organizations.

Simulations have significantly contributed to the analysis of construction, and Discrete Event Simulation has been a primary means of simulation focusing on Construction Operation. In this paper, the authors address the importance of Construction Context as another realm for understanding and managing construction through representation of overall behavior of construction associated with Construction Operation. The issues raised from representing both Construction Operation and Construction Context together in a simulation model are discussed, and a hybrid System Dynamics and Discrete Event Simulation approach is proposed as a comprehensive simulation framework for that purpose. Briefly, its application to construction is also discussed.

Safety is one of the most important topics in construction industry. This paper describes ongoing research and proposes a framework to model safety-related standards to support automated reasoning for safety improvement and construction site hazards prevention. The proposed system architecture integrates a construction methods model and an integrated project model to achieve automated identification of safety requirements imposed by standards. The authors expect that the envisioned system will facilitate site safety improvement and management in an automated manner by supporting identification of safety requirements during the design and the construction phase. This would allow taking these requirements into account early in a project life cycle, possibly affecting the design and schedule of a project, and supporting better guidance for field engineers and inspectors during safety planning and construction safety inspection.

The paper presented reports on the development of a distributed simulation and optimization platform for underground engineering. The platform integrates individual software applications from all fields of underground engineering to support engineers in the design of underground constructions. This paper addresses two aspects of software integration that are considered to be crucial for the development of the platform: The definition of a workable product data model that provides a basis for the data exchange and the loose coupling of individual software applications by utilizing a service-oriented architecture.

The need to satisfy many functional requirements makes building envelope performance assessment difficult. Furthermore, complexity and diversity of building regulations make the understanding of building codes and regulations a complicated task. This paper presents a method for automatically checking building code compliance according to the simulation results of building envelope performance. Firstly, building codes or regulations are represented as a knowledge base using decision tables in XML (Extensible Markup Language). Then, building envelope information is extracted from an IFC (Industry Foundation Classes) digital building model. Simulation programs are used to simulate the functional performance of building envelopes under variable exterior conditions. Finally, a prototype system HAMBE (Heat, Air and Moisture performance of Building Envelope) is developed for automated building code compliance checking. With the aid of this application, the automated building code compliance checking can help architects, engineers and other users query building codes and regulations quickly and efficiently.

This paper presents an overview of a specification for a Building Information Modeling (BIM) tool for cast-in-place reinforced concrete, covering engineering, construction planning and placement. It emphasizes the differences between site placed RC modeling from the already developed modeling tools for steel and precast concrete. The differences include physical characteristics, structural connections, production planning and support for on-site dynamic adjustments.

As building product models become more common, more attention is being paid to the question of how to evaluate and validate these models. Researchers and developers have utilized a variety of techniques including field tests and expert reviews, but there is no clear consensus on which methods are appropriate in which circumstances. A better understanding of how existing building product models have been evaluated and validated in the Architecture/Engineering/Construction (AEC) domain can help to determine what methods should be considered for future modeling initiatives. This paper describes procedures and metrics used to verify a data model that is developed for Building Commissioning (BC). We first analyzed how building product models in the AEC domain are evaluated and then described the three characteristics identified as the metrics for evaluating Building Commissioning Data Model. These characteristics are the scope, the ability to support BC functions and the flexibility.

This paper presents a new construction simulation approach using Cell-DEVS techniques, which allows considering site spatial constraints and the sensitivity analysis of different site layout patterns. The proposed approach includes three phases: pre-processing to configure the simulation, main-processing where the simulation is executed, and post-processing, which incorporates animation and sensitivity analysis of the results. Using Cell-DEVS modeling, spatial resource allocation, worksite layout, as well as the movement of equipment can be explicitly analyzed and visualized. Spatial conflicts can be detected, resolved, and compared based on different site layout patterns. As a result, the accuracy of simulation is improved, especially for situations where spatial conflicts are critical. A case study is presented to illustrate the procedure for modeling and analyzing the sensitivity of simulation results considering several site layout patterns. The difference between the results of MicroCYCLONE and Cell-DEVS illustrates that in some cases the impact of spatial constraints on productivity is significant and should not be neglected. Based on the present study, it has been found that Cell-DEVS simulation is an effective tool for space-related analysis in construction project.

A new approach based on collaborative agents is proposed to coordinate construction equipment operation in real-time. Cranes are taken as an example due to their frequent usage in construction for cooperative work. Literature related to agent-based applications is reviewed to investigate the feasibility and advantages of applying agents for equipment operation. Information about the equipment to be shared between agents is identified and the requirements for applying collaborative agent-based systems in construction are discussed. Lift task is decomposed into several steps comprising different actions for each crane, and negotiation is used to resolve the conflicts. A case study about a bridge rehabilitation project is used, where two cranes are working together to lift a panel on the bridge with height limits from the bridge structure. A simulation model is under development to create a virtual environment showing the work site, the bridge structure and two virtual cranes. In our preliminary test, agents can dynamically control the kinematic action of the two cranes respecting the functional constraints for safety and efficiency of operations.

The deterministic seismic assessment methods remain insufficient to define structural behavior under earthquake effect due to the uncertain and random variables in the analysis. Including the probabilistic approaches into these analyses for definition of seismic structural behavior will give more rational results. In this present study, it is aimed to realize the probability based seismic analyses of reinforced concrete frame structures and to emphasize that a probabilistic seismic assessment is necessary to define the structural seismic behavior realistically. For this aim, first, nonlinear analyses as push over analysis and time history analysis with selected earthquake data are realized. The results of push over analyses are compared with time history analyses results. Second, for the same R/C frame structures, the fragility analysis which is a system reliability analysis with correlated demands and capacity is performed to establish the probabilistic characterization of the demands of the R/C frame structures. Fragility analyses are realized with three different parameters as (peak ground acceleration), PGV (peak ground velocity) and PGD (Peak Ground Displacement) based. The obtained results are compared to evaluate the parameters used in fragility analysis.

The generation of concepts in the construction industry involves the interpretation of syntactically defined symbolic notations, such as logic, frames, semantic networks, natural language, and of other forms such as visual representations. These notations are deliberately organized to define concepts. The understanding and characterization of concepts into symbols and other forms of representations are addressed for sharing the concepts within the construction industry community. Models are based on symbols that are intended to refer to certain entities of the world with properties and relations embedded within them. Models group a set of relations that characterize concepts with the purpose of being shared and understood by members of the community. However, models suffer from the limitation that logic and the symbolic notations have, they cannot capture the richness of the phenomena of the world in their syntactic notation. Instead of inquiring within the paradigm for the right "choice" for representing concepts, this research aims to direct attention towards the process of interpreting a representation, as well as, that of translating a concept from the agent's mind into a representation. Interpretations are the source of the divergence for asserting the correct meanings of the representations. The central idea is to investigate the role of `similarity' relations that express semantics in construction representations. This investigation searches for valid reasons that explain the divergence in the understanding of information when actors in the construction domain generate representations to communicate concepts and, at the same time, when the actors perceive the representations that are used to interpret the concepts.

Electrical construction firms use different types of information systems to deal with various business processes. Although in theory researchers find that information systems can help improving productivity, in reality electrical construction firms still suffer from the lack of understanding to the value of information systems. Previous studies have suggested many reasons why construction firms lag in adopting information technology. Through case studies, this paper, exploring the application of information systems to electrical construction firms based on the Resource-Based View (RBV) theory, suggests that the focus of existing applications is mainly on mediating internally-oriented business processes. The resulting capabilities may not necessarily help electrical construction firms translate the value of information systems into their long-term competitive advantage. Consequently, future studies are recommended to determine whether computer-mediated externally-oriented business processes should be identified, developed and integrated with the internally-oriented business processes.

People generate and develop concepts in informal settings through gesture language, verbal discourse, and sketching. Current knowledge capture and reuse solutions are unable to utilize the relevance embedded in these multiple multimodal streams of communication. As a result, most of the archived content becomes hard to understand and reuse. This paper presents DiVAS (Digital Video-Audio-Sketch) a system for cross-media knowledge capture, search, retrieval and re-use of rich, unstructured, multimedia digital content stored in large corporate repositories. This is achieved through seamless transformation of analog activities such as gestures, discourse, and sketching that take place during creative and informal communicative events among stakeholders engaged in building projects, into integrated digital video-audio-sketch episodes. DiVAS presents a cross-media semantic analysis and data mining methodology of indexed digital video-audio-sketch footage that captures the creative human activities of concept generation and problem solving. Together, they provide a macro-micro index to large enterprise archives of rich, multimedia, and unstructured content. Knowledge re-use is facilitated through contextual exploration and understanding of the rich content that is retrieved.

Many researches are undergoing to enhance the current practice of Bridge Management Systems (BMSs). This paper provides a critical review of new research directions in BMSs with emphasis on Information Technology and computing. Firstly, new technologies and methods for mobile data collection, structural health monitoring, and non-destructive evaluation are reviewed along with related opportunities and challenges. Secondly, planning and decision making in BMSs including forecasting models, optimization models, and decision-support systems are discussed. Finally, the paper addresses potential extensions in transportation management that can be integrated with BMSs.

Temporary structures (i.e., scaffolding, shoring) represent an area of considerable significance in the construction process, having a large influence on the quality, safety, speed, and profitability of construction projects. However, current industry practice does not have a systematic way to generate temporary structure plans due to the lack of a formalized way to represent the specific project situations and the planners' rationale to select temporary structures for a given specific project situation. Temporary structure planning is in general handled manually and is time-consuming and error-prone. Information-technology-based methods are the most promising approach to improve the timeliness, correctness, and consistency of the temporary structure planning process. Building on and extending the prior work on representing product and process information, this paper presents formalized component and action features that helps represent specific project situations. We also formalize a taxonomy for temporary structures that helps select appropriate temporary structures for given situations. The formal representation of features and taxonomy for temporary structures provide the theoretical foundation for developing a computer-assisted method that helps construction engineers generate temporary structure plans rapidly, consistently, and thoroughly.

Most conventional Origin-Destination models work with limited link observations with help of target demand or other prior information. This paper presents a new approach for estimation of Origin-Destination flows and route choice parameters simultaneously from incomplete link flows. By presenting approximate joint probability distribution functions of the temporal link traffic flows on a network, the conditional likelihood functions for estimating dynamic O-D and route choice parameters are derived. An Expectation-Maximization (EM) algorithm is proposed to estimate those parameters based on incomplete link flow data. Preliminary results indicate that the new approach can provide validated results.

Project participants typically maintain their own schedules for a given project. The multiple views of the participants are not easily reconciled due to varying levels of detail and different business processes. This in turn leads to poor schedule coordination in practice. The Process Connectors project seeks to enable distributed schedule coordination via a unified, multiparty schedule representation while enabling each participant to maintain its local view of the project. Past work in the Process Connectors project has demonstrated a representation for reconciling temporally defined multiparty views across different levels of detail. This paper reports on extensions of the base representation to enable exploration and evaluation of alternative schedules. The extended capabilities facilitate schedule re-coordination in response to a schedule change such as an acceleration or delay. Specifically, this paper describes the capability to analyze a unified schedule, identify conflicts and inconsistencies, recommend alternatives, and to describe alternatives in the local context or view of each participant. The tools developed by the researchers enable project participants such as subcontractors to accept or reject changes, providing a mechanism for incorporation of human decisions and support for machine generated recommendations. The capabilities for basic analysis and exploration of alternatives at both a unified and local level are expected to speed up and improve practitioners' responses to changed conditions on projects.

This paper presents two approaches of modeling the deterioration of highway bridges that can lead to an effective maintenance management strategy. Probabilistic state-based/time-based models are used to predict the global or macro-response of bridge components for network level analysis, while reliability-based mechanistic models are used to predict the detailed or micro-response of bridge components for project level analysis. Probabilistic state-based/time-based models are developed using qualitative performance indicators (condition ratings) that are determined through visual inspections to identify the overall condition of damaged components in a bridge network. Reliability-based mechanistic models are developed using quantitative performance indicators (physical parameters) that are determined through detailed condition surveys, analytical modeling, and empirical investigations to identify the extent and severity of specific deterioration mechanisms for safety critical structures and/or highly damaged components. The condition rating data obtained from the Ministére des Transports du Quebec database and the condition assessment of the Dickson Bridge in Montreal, Canada were used to demonstrate the development of the two approaches in modeling the deterioration of concrete bridge decks.

The development of new computing technology to support designers is typically initiated by developments in various areas of information technology such as artificial intelligence, information systems, and human computer interaction. The adaptation of these developments to support designers usually requires developing the new technology beyond its original capability to address the complexity and open-endedness of designing. Often there is a promise of improving the quality of the design, or improving the efficiency of the design process. Delivery on this promise is not easily evaluated or convincingly delivered. Recent developments in studying and understanding design cognition provides the opportunity to assess the impact of new technologies on design and to direct new developments in response to the impact.

The paper addressed the lack of and the need to have domain-specific reference collections for supporting text-based information retrieval researches/applications in the domain. Different methods and examples that aided the development of reference collections were overviewed and a collection with 1182 documents and 11 information requests was generated. A task for testing the reference collection was implemented to illustrate the uses and potential applications of the collection. The precise testing task was to evaluate the segmentation-translation strategy for the Chinese contents within the collection for cross-language IR operations. The test results suggested positive answers to the test task. It is expected that the research outcome will provide standard, sharable, and reusable testing resources to support advanced text-retrieval researches and applications in AEC/FM.

As a result of EPA consent orders to enforce sewer systems inspection, an unprecedented amount of data are being acquired and stored in municipal sewer authorities and departments. Also, new technologies have been developed to increase inspection efficiency, such as sonar and laser scanners, allowing more complete characterization of sewer attributes and allowing better inspection data acquisition. Furthermore, sewer systems data have been deposited in Geographical Information Systems allowing the manipulation and association of spatial and non-spatial attributes. This paper discusses the potential of applying spatial data mining tools for extracting relevant and non-trivial information from spatial databases. This application aims at providing better decision making support for inspecting and maintaining sewer pipelines. Initial analyses show that the lack of integration and consistency of these growing databases is the first limitation to be overcome in order to successfully adopt any data mining tool.

This paper proposes a new nature-inspired method for achieving robustness of structural designs. In particular, biological processes of coevolution encoded in coevolutionary algorithms are proposed here to concurrently search the representation spaces of structural designs and of their loading cases, hi the proposed model, coevolutionary algorithms use two populations which competitively coevolve. The first population contains structural designs, while the second one contains loading cases. The quality of each individual structural design in the first population is determined by measuring how well it performs against the loading cases from the second population. On the other hand, the goodness of each loading case depends on the number of designs it "defeated," i.e., how many designs didn't succeed in satisfying design requirements (e.g., maximum internal forces, maximum displacement, etc.). This approach encourages generation of robust structural designs performing well against various loading cases. The proposed coevolutionary design method is illustrated by a simple demonstration problem of a welded beam design. The paper also presents initial research conclusions and discusses the most promising paths for future research.

Capturing project data and storing it in an integrated way during construction is important not only for project monitoring, but also for reuse of project historical knowledge in upcoming projects. Various data items need to be collected at a job site and integrated to support decisions during and after construction. There are issues associated with utilization of these data items as these data items typically come from a variety of data sources, are stored in multiple databases and might not be at the level of detail required for a specific decision. To be able to fully take advantage of a variety of data that is being collected, these issues need to be addressed. This paper overviews a multi-data source fusion approach and describes a set of mechanisms implemented to support production rate related decisions of cost estimators and productivity analyses of project managers during construction.

This paper presents the preliminary results of a research project that seeks to investigate the use of advanced image processing, computer vision and pattern recognition technologies, to facilitate asset inspection and condition assessment of sewer pipeline infrastructure. This research aims to provide a basis for sewer pipeline inspection and condition assessment, enabling automatic detection and recognition of defects and/or critical features from sewer pipeline inspection videos and images. An approach for automatic detection and recognition is presented in this paper. The major steps of the approach are illustrated by examples using actual sewer inspection visual data.

Interdependencies among critical infrastructures become more and more complex as technology advances. Through interdependencies the disruption of one infrastructure can cascade into other infrastructures. With the rapid growth in demand of electricity, vulnerability assessment of electricity production and its availability has become essential. One of the critical components of the electricity production value chain is extraction and delivery of fuels. This paper presents the preliminary results of a research project that aims to analyze the vulnerability associated with delivery of fuels and to ensure availability of fuel supplies, by providing insight into likely vulnerability. In this research project, a framework for electricity production vulnerability assessment was proposed. Different data sources were integrated into a data warehouse to allow interactive analysis of enormous historical datasets for coal transactions and coal transportation. The analyses help decision makers understand the impact of fuel delivery disruption and the vulnerabilities in the coal transportation system.

Validating simulation models requires rigorous testing to establish the accuracy to which the real world operation under study is captured by the model. This exercise, in large part, requires learning about the simulated world. Computer games, a type of virtual reality environment, are capable of being effective learning tools because gamers are capable of understanding the underlying simulated world based on the game's reactions to their actions. The gaming perspective can be extended for model validation. This paper describes how game-like simulation systems can significantly expand the nature and extent of model testing during validation, and the challenges faced in enabling such systems for construction. Specifically discussed are the challenges in developing virtual reality environments based on current 3D animation technology to establish user interaction with underlying discrete-event simulation models. This paper concludes with a brief overview of the related work completed and in progress by the authors.

It's an important issue for maintenance management in auxiliary facilities of transportation. Meanwhile, the maintenance budget always is the key factor to keep facilities' function. This research focuses on transportation facilities to explore its life cycle cost (LCC) and then provides administrators as a reference factor when they estimate maintenance budget. This research defines three maintenance strategies: reactive maintenance, preventive maintenance, and assessment maintenance. The database of this system includes basic data, inspection data, and maintenance data to provide the prediction base of life cycle cost. For reactive maintenance, because maintenance events are independent, this research uses Markov chain to predict the probability when any event occurs. According to the probability, the analysis system can estimate future maintenance cost. For preventive maintenance, it considers expendable products to analyze maintenance cost by considering its lifetime. For assessment maintenance, this research focuses on infrastructure condition, which will be influenced by time and environment factors. It can react to the history of inspection data and use these data for regressive analysis to predict future condition. According to this future condition, engineers can estimate its maintenance cost. Finally, according to these three kinds of maintenance strategies, system can calculate cost for each year in the future to provide a budget suggestion for administrators.

The median barrier installation project for the 4-lane or wider national highways is in progress in order to prevent accidents. In order to maximize the effectiveness of median barriers, the priorities of median barrier installation should be decided reasonably and realistically by an adequate evaluation process. The monetary evaluation methods that have been usually used to give priorities to the alternatives have some limitations in reflecting various factors, especially considering qualitative variables that are related to decision-making problems. On the contrary, the AHP (Analytic Hierarchy Process) is a flexible model that deals with the qualitative variables and allows us to make decisions by personal judgment in a logical way. This study establishes a process for deciding priorities for median barrier installation using AHP (Analytic Hierarchy Process). We provide a systematic framework for the decision-making process on, the basis of conditions of road sections and the overall priorities of evaluation factors. This framework reflects multiple criteria (economic efficiency, safety, possibility of installation, and regional equity) synthetically, and it gives the greatest weight to safety (prevention of head-on crashes, rates of which are most strongly affected by median barriers).

A traffic accident analysis method based on the accident risk index according to the combination of alignment elements is developed and tested applying geographic information systems (GIS). This study is based on crash experience on curves of 4-lane expressways in Korea from 1996 – 2000, and that finding relates only to curves. Impacts of alignment elements on traffic accidents have been identified by examining accidents that occurred under different alignment conditions and by investigating traffic accident risk indices (TARI). Traffic accident rates are estimated more reasonably by considering the interaction between alignment factors and the design consistency. Traffic accident risk indices and risk grades are suggested in the traffic accident data-based approach. Finally, estimating traffic accident rates, evaluating the level of risk and then visualizing information graphically by means of GIS are combined into one system called the risk rating system. This risk rating system is expected to play a major role in designing expressways and developing countermeasures for expressway sections susceptible to traffic accidents.

This paper reviews research work that has attempted to assess the financial benefits of adopting sustainable design and construction practices, and identifies a connection to information and communication technology (ICT) used to facilitate the adoption of those practices. A review of the literature found that: researchers disagree on the precise impact of sustainability upon the whole life costs (WLC) of buildings; the impact of sustainability upon usage costs tends to be ignored despite their considerable size; and the use and adoption of ICT tools remains costly, limited and inefficient in sustainable projects. Future research needs therefore to focus on: investigating a sufficient number of conventional and sustainable buildings, assessing all types of long-term costs incurred in those buildings, evaluating buildings' usage costs in more details, and using empirical documented cost data whenever these are available. Future research also needs to show ways of improving sustainable design and construction processes by: assessing the specific impact of ICT tools on related processes, assessing the collaborative decision-making process in general, and developing a comprehensive model to ensure effective adoption and implementation of ICT solutions that have shown to improve design and construction processes.

This communication shows a procedure aimed at aiding in the Landscape Impact Assessment caused by new lineal infrastructure services such as motorways, to be constructed. Measuring the magnitude and intensity of linear infrastructure facilities visual impact turns out to be exceedingly complex because infinite views exist that potentially must be considered. How can we reduce this amount of views to a discrete and manageable set? The core of the problem is that there is a non finite set of landscapes to be considered (and analyzed); however, according to the proposed model, if some suitable Computer Graphics libraries are used, it is possible to automatically produce a reduced catalog of realistic images simulating, each of them, the effect that the new infrastructure causes on the environment, just at the sites where the landscape is liable to more damage, and seen from the points of view where the number of potential observers is at a maximum. Such computational tool is called MOYSES, an automation solution integrated in Autodesk's Civil 3D, although it is easily portable to other systems.

One significant challenge in developing life cycle performance models for buildings is how to define "performance". While the classical definition of performance of a building is based on safety and serviceability criteria, the definition for high-performance buildings for sustainable developments is based on additional criteria mostly related to energy and environment such as improved energy, economic, and environmental performance. The guidelines for defining these criteria include imprecise, or linguistic measures (e.g., "high", "medium", or "low"). These types of measures would lead to soft/fuzzy evaluations that cannot be added using simple mathematical or probabilistic models. Using the theory of possibility, a new robust metric for evaluating sustainability in buildings is being developed. This new metric is necessary because existing evaluation systems such as LEED and Green Globes lack the ability to gain partial credit and overlook the existence of several types of uncertainties associated with the evaluation process. A case study, presented here, demonstrates how the new metric integrates definitions across existing sustainability measures using possibility distribution.

Results from various research teams over the last fifteen years have demonstrated the suitability of evolutionary computation as a technique for supporting decision making during design and especially during conceptual design. However, there are still some significant problems to be solved if these techniques are to become practical and robust design tools. These shortcomings are discussed and the remainder of the paper then focuses on the inadequacies of current representation techniques for supporting topological reasoning and looks at a possible new way forward. This is based on a method of describing the geometry of objects which uses the way that the object topology is generated rather than being based on a static collection of points, lines and planes. The work described is an ongoing project.

In order to evaluate the status of the project at any particular point of time, identify problems and enable project managers to make the correct decisions and control the project effective performance measurement and analysis systems should be used on construction sites. This paper presents application of multivariate statistical process control (MSPC) techniques to monitor the construction site variables. Multivariate statistical process control (MSPC) has found growing applications in recent years for controlling processes in chemical plants and other manufacturing processes. The MSPC combines a large number of variables into few independent variables, which then can be monitored and any process deviations from the normal operating conditions can be identified with corrective actions suggested. Utilising MSPC technique construction process variables can be modelled using historical data and establishes patterns of correlated variables. The current on site variables can be analyse and report to project management in order to make effective future decisions. The statistics of external variables and internal variables influencing construction site operations were identified using a real life case study. The results of modelling the variables and conducting experiments with MSPC are analysed and discussed in this paper.

This paper describes the analysis and design of an application based on the metaphor of software agents. The agent paradigm was used in this context to address problems emanating from the fragmented nature of tasks involved in the e-procurement of construction products. Since none of the existing agent development environments could be used in isolation to deliver an entire application with the desired functionality, it became necessary to conceptualize the proposed prototype as linked modules that could be developed separately using different tools. The objective of this paper is to show how programming the prototype as a collection of sub-systems that need to interact with one other presented an opportunity for exploiting object-oriented thinking. More specifically, it underscores the advantages inherent in using the abstraction provided by multi-agent Systems Engineering methodology (MaSE) and its associated agentTool environment in the analysis and design of components of a community of agents.

This paper describes the mathematical equations, embedded in a simulation environment, that are needed to simulate the deterioration of pavements as well as the renewal or maintenance strategies. The paper shows how highway maintenance managers can consider the impact of choosing one maintenance policy alternative over another through "what-if" analysis. Highway maintenance managers (transportation officials at the District or State DOT level) are able to consider such things as the available budget and target goals for the overall condition of the highway network in order to determine the best maintenance policy. Thus, maintenance managers are able to compare strategies based on preventive maintenance versus strategies that wait until pavements have become visibly distressed.

Virtual experiments are one of the integral parts of the advanced civil engineering practice since they eliminate time-consuming and expensive laboratory studies, and they are useful for educational and training purposes. In the present work, a number of virtual experiments for investigating the corrosion of reinforcement in concrete are designed, and the effect of different parameters on the corrosion process is examined. The design of the experiments is based on non-linear solution of Laplace's equation with polarized surface boundary conditions by the finite element method, for which an under-relaxation technique is implemented. Using the results of the virtual experiments, a closed-form solution for the considered domain is obtained. By using this solution, the effect of a number of factors that affect the corrosion process can be investigated; an example of this investigation is presented. These experiments can also be effectively used for service life design and structural health and integration monitoring purposes; these two approaches are discussed in detail.

The building infrastructure operations and maintenance phase is usually the longest and most costly phase of a building's lifecycle, ultimately exceeding the total cost of initial design and construction. Targeting these operations and maintenance costs and the cumulative sustainment and renewal costs can have a significant effect on reducing total cost of ownership. This requires planning and correct timing of work, to reduce the adverse affect of deferred maintenance and repair which lead to accelerated deterioration and restoration costs for the structure. There is thus a financial payback in terms of reduced lifecycle cost for correcting distresses and maintaining a quality condition level through proactive facility management. This paper will examine the work management practices necessary to reduce total lifecycle cost of ownership for building facilities using a computational component repair/replacement simulation model. This model incorporates condition measurement, condition prediction, component service life expectancies, and corrective repair/replacement scenarios. Examples will show how a best practice approach to facility management can lower total maintenance and repair costs by nearly half over 50-year lifecycle.

In this paper, a multi-criteria decision making (MCDM) framework is introduced for evaluating and comparing a wide range of privatization schemes for infrastructure facilities. The proposed framework helps the decision maker identify all stakeholders, their options, and their preferences. Two MCDM techniques are used consecutively to simulate the process used in an actual privatization case study to arrive at the most suitable decision: (1) the Elimination method that eliminates unfeasible alternatives; and (2) the Scoring method to score the short-listed solutions and arrive at the best one. Based on the proposed framework, a computerized decision support system has been developed and used on the case study. The system proved to be useful for structuring the process and arriving at a better decision than actually made. Areas of improvement to the proposed framework to consider uncertainty and stakeholders' negotiation preferences are then discussed.

A major concern for construction industry participants is the occurrence of claims and change orders which cause significant losses in terms of schedule delays, and cost overruns. The use of Alternative Dispute Resolution Techniques (ADR) has been shown to reduce the impact of these claims on the project. These ADR techniques require capital expenditures that need to be justified in construction projects with budget constraints. This paper investigates the use of real option valuation under competitive entry to evaluate ADR investments and determine the optimal investment timing.

This paper presents an IT-based collaborative framework that facilitates efficient and immediate coordinated response to disasters involving critical physical infrastructures in chaotic, hazardous and hostile environments. The system incorporates web collaboration tools, Radio Frequency Identification Tags (RFID), Geographic Information Systems (GIS) and Building Blackbox Systems (BBS). Through the integrations of these technologies, the system provides a medium for the first responders to collaboratively respond to disasters. Critical information regarding buildings, such as blueprints, is stored and can be obtained from the BBS in order to facilitate the evaluation of building integrity. RFID tags are used by first responders to store building assessment information. Then, by using a mobile ad-hoc network, the building assessment information is distributed, so that other first responders and decision makers with access to the network will be able to view all the information available on a single electronic space, such as a geographical map. With the building assessment information on the electronic space, responders can perform an optimal resource allocation route analysis using GIS for immediate rescue of trapped victims and reconstruction of the disaster site. In addition, key decision makers at different locations can evaluate the overall system wide condition of the disaster and hold sessions to make integrated critical decisions through the web collaboration software —inMeeting. Prototype system development and testbed simulations of the system have been completed with encouraging results at Institute in Champaign, Illinois, USA.

This paper describes the current state in the development of a computational steering environment (CSE) for indoor air-flow simulation. The system is especially desiged to provide an interactive evaluation of thermal comfort. It consists of an integrated, VR-based visualization client, a parallel computational fluid dynamics (CFD) kernel and a 3D grid generator component. The CSE is intended to support engineers with an easy-to-use tool for designing HVAC systems (heating, ventilating and air conditioning), for example, in the early stages of a project. By utilizing high-performance computing, the tool enables the investigation of indoor air-flow scenarios approaching closely to "real-time". The user interface for visualizing simulation results and the "steering" of the simulator have been combined to form a single application front-end. This allows an intuitive access for steering the simulation, changing the set-up of geometry and boundary conditions and subsequently exploring the results. The simulation kernel is based on a hybrid lattice Boltzmann method with extensions for large-eddy simulations of turbulent convective flows. The next steps in the project are to improve the VR client, enhance the treatment of boundary conditions in the computational kernel and extend the simulator in conjunction with partners in order to integrate a local thermal comfort model.

Engineering systems of deformable bodies held together by dry friction, gravity and preload can be found in many engineering applications such as the railway ballast, structures connected by bolts and rivets. This paper studies the behavior of a two dimensional model of deformable block-incline system under dynamic loading of harmonic vibration by using finite element modeling and by experiments. It was found that the integrity of the system can break down, and that there are three regions of no relative movement between the block and the incline, the block moves down the incline and the block moves up the incline, depending on the value of excitation parameters of harmonic acceleration amplitude, frequency and the amount of preload between the two surfaces.

The development of fire standards that lead to safe and economical construction does not happen by chance. It is actually a complex process that requires a thorough understanding of the physical nature of fire and how it affects the behavior of structural systems. One way to do this is to conduct experimental research on full-scale or model systems and learn from their results. Although this can and has been done, it is, nevertheless, quite an onerous endeavor. This paper presents a methodology to simulate the behavior of an open steel frame (such as a parking structure) under the effect of fire using a specially designed computer tool. Upon definition of the geometry of the frame and location and intensity of the fire by the user, the spreadsheet based program evaluates the variations in temperature and their effects on the properties of the material using a constant time increment. Structural displacements are then computed and graphically presented.

Built in the mid-1950s New York State Thruway is one of the longest toll superhighways in the nation. To preserve the infrastructure condition at an acceptable level for safe operation, the Thruway infrastructure requires regular maintenance and repair. Performance-based management in this context aims at monitoring and improving the infrastructure's life-cycle performance with timely strategic, preventive maintenance and minor repair. Preservation of the Thruway system is achieved by compiling relevant input information and interpreting the output results from life-cycle inventory analysis and impact assessment. The management approach combining facility performance with life-cycle analysis has been particularly effective and beneficial in identifying and prioritizing maintenance actions necessary for Thruway operation as an interstate toll-road. Preserving this primary roadway using the life-cycle approach brings the subject of performance and preventive maintenance to the forefront of sustainable practices.

This paper presents a measurement system design methodology that incorporates damage scenarios. One of the goals of a measurement system is to detect damage for safety and for management of maintenance activities. This study builds upon previous research at EPFL in the area of model based diagnosis. An existing bridge in Switzerland is used to illustrate how damage scenarios are identified and a population of models are generated. A greedy algorithm is used to place sensors such that there is maximum separation between the predictions of the models in the population.

Decade after decade of expansion in urban areas has meant that underground infrastructure has descended into what can only be described as a labyrinth: the myriad of phones lines, electricity cables, gas pipes, cable TV, fibre-optics, traffic signal wiring, street lighting, circuits, drainage and flood control facilities, water mains and sewage pipes, to name but a few. In places, there is a lack of space available under the surface within which to accommodate all of these services, and as such it creates significant potential for underground `space competition'. Additionally, the problem is aggravated by the de-regulation of utility services where multiple service providers seek to place their networks underground. These and more problems arise through the lack of accurate and precise monitoring of buried assets. Given that the scale of the problem associated with locating underground infrastructure and associated systems is enormous, the research discussed in this paper sets the scene for the drivers of improvements in the current unsatisfactory buried assets location and condition monitoring methods. It also presents a new IT locating approach based on RFID technology, which may be able to overcome problems concerning buried assets location.

Recently, monitoring of existing tunnel environment has been increasingly more important due to the progressively risen public concerns, especially in extreme long tunnel like Hsuehshan tunnel in Taiwan. Such extreme long tunnel can easily cause significant hazard due to automobile accident. Therefore, developing an efficient and robust monitoring system to inspect the circumstances of tunnel is the momentous research. Capabilities of wireless sensor devices and networks have significantly more advantages over those of conventional monitoring instruments, which are wire-based systems for acquisitioning and transferring. Motivated by this, a study of design and integrating of wireless sensing system for monitoring existing tunnel situation is presented in this paper. The overall system design comprises two major units, a wireless sensing unit and a wireless receiving unit. Wireless sensing unit contains two functional modules, (1) sensing and data acquisition module; (2) microprocessor with wireless communication module. Only humidity, temperature, gas, light and photo sensors are investigated in this work, but any preferred sensor can be easily adopted with this smart transmitting scheme to realize a wireless sensor network system. Wireless receiving unit also consists of two functional modules, microprocessor with wireless communication module and a gateway. Experimental study was conducted to investigate the proposed prototype. Investigational results revealed that the feasibility of wireless sensor network in existing tunnel environment monitoring and maintaining.

This paper introduces an on-going research for developing a dynamic path planning system to improve mobile robot navigation in a dynamic building construction site by integrating a set of sensor-equipped robots into a real-time indoor positioning system. In the proposed navigation system, the communication between mobile robot, an ultrawideband (UWB) position system, and a portable computer is implemented over a wireless LAN. The location data from the UWB sensor network enables accurate visual representation of the mobile robot to be displayed in a 3D CAD drawing in a real-time manner. The tested positional accuracy of the wireless configuration of the current UWB system is about 36 cm. The key advantages of the proposed approach are: (1) this approach is fully untethered self-powered wireless system with real time data delivery, and (2) the developed position tracking and robot control software modules can be easily imbedded into standard CAD programs, thus reducing computational burden on developing a new graphical user interface (GUI) for different building applications.

Construction productivity, one major project performance indicator, requires the continuous assessment of construction progress over time. Current practices for construction progress assessment are labour intensive, expensive, and generally result in partial and sometimes erroneous information. It is thus difficult to make appropriate and timely management decisions. However, recent three-dimensional (3D) Computer Aided Design (CAD), 3D scanning and global positioning technologies present an opportunity for developing more efficient, robust and automated approaches. After reviewing and analyzing previous works conducted in the field of automated object detection, this paper presents a new approach taking advantage of global positioning technologies for robustly retrieving 3D CAD elements within 3D scanned data. This approach is implemented and experimented in laboratory. Results are conclusive towards further experiments for its application to many different fields including automated construction progress assessment for effortless productivity tracking.

This paper introduces a prototype framework for automated material tracking (AMTRACK) system. A new ZigBee-based localization technique with hybrid sensor interfaces — combination of radio frequency and ultrasound devices — is presented to improve the accuracy and efficiency of materials tracking. AMTRACK system will provide a potential to increase location accuracy by eliminating multipath property of radio signal propagation. In addition, mesh network capacity of the ZigBee standard will leverage the applicability of the AMTRACK prototype in complex construction projects.

Rapid local area modeling, with the assistance of high frequency laser scans, is a valuable tool for construction site resource management applications. However, as a central component of the modeling process, the rapid processing of tens of thousands of scanning points in a fraction of seconds is still a challenging task that requires further investigation. This paper describes a study aimed to investigate the performance of various data processing algorithms for range points that were captured from laser scanners in both indoor and outdoor environments. An integrated range data processing module was developed in this study, allowing for quickly experimenting with various combinations of data filtering, transformation, and segmentation approaches. The identified group of processing algorithms could robustly handle sensor noise and accurately process high frequency local area laser scans.

This paper presents a method, which can be implemented under limited resources such as wireless sensor network devices, for damage detection of civil structures. The detection method is applied to transient waves from vibration responses, and it consists of Haar wavelet decomposition, thresholding, quantization and differentiating metric. Before the differentiating metric, a target signal is compressed into the wavelet coefficients "signature". The results indicate that a single measurement channel without time synchronization of other measurement points is effective for instant damage detection through the case study using the ASCE SHM benchmark program. It is also shown that we can reduce the data to a small fraction of the original data volume using this method, while retaining enough information to detect structural damage and its severity. The approach illustrated in this paper implies a promise of wavelet-based data compression and analysis for the increasing volume of Structural Health Monitoring (SHM) data.

This research focuses on the approach of leveraging the advancements of wireless Ultra-Wideband (UWB) positioning and reflectorless Range Imaging (RIM) sensing technology in the construction domain. Although emerging sensing technology and its potential applications promise to have large benefits for the construction industry, they often are not applied in the field for various reasons. Since data collection and analysis are too far apart, site management personnel relies on existing management methods rather than innovative sensing technology that can assist and provide information for intelligent decision making tools. In today's competitive business environment, however, timely and accurate decision making becomes increasingly necessary and requires keeping track of productivity to ensure that the construction project is on budget and on time, as well as that all work tasks are performed safely. This paper presents the initial framework of a proposed research in tracking resources on construction sites for productivity and safety performance measurements. The literature review includes a discussion of potential enabling technologies. The main part focuses on the potential of merging the advantages of the selected sensing technologies in regards to productivity tracking as well as safety. The proposed research methodology and an experimental plan with preliminary results are presented.

This study assesses the reliability of active radio frequency identification devices (RFID) and Global Positioning System (GPS) sensors that, when combined with localization algorithms, can be used to locate tagged materials in construction sites. Specifically, this paper presents experiments used to assess the deviations from materials' actual positions to their estimated locations according to both centroid-based and proximity-based algorithms. The authors also analyze these deviations when considering only RFID signals with strengths stronger than certain threshold values. The results of this research also suggest that it is possible to infer relative distances from RFID-sensors to tagged-materials according to signal strength characteristics. Field experiments simulating typical construction conditions are used for testing this approach.

In order to keep track records of periods of actual usage of light temporary facility members such as pipes, scaffolding plates and frames, experiments were executed by using passive Utlra-High Frequency (UHF) band Radio Frequency Identification (RFID) tags. Tags were pasted onto steel pipes, scaffolding plates and frames for investigating the readability in a number of different ways. The thickness of a base for appropriate opening between a tag and a metallic object, the location of tags, and installation methods were investigated to achieve simultaneous identification of multiple members. The experiments showed UHF band RFID systems can be used and better performance over a compared 2.45 GHz band passive RFID system. A prototype database system for reading the RFID tags to obtain the ID data and for keeping track records of the usage of the light weight temporary facility members was developed. This system can be used for selecting old temporary facility members to be abandoned.

Surface Plasmon Resonance (SPR) is an emerging approach to the perennial problem of condition monitoring and pollutant and irritant detection. The technique involves surface plasmon waves being excited at the sensor surface by a monochromatic light under conditions of total internal reflection. These waves are sensitive to changes on the sensor surface such as the presence of an analyte; this will cause a change in refractive index. It is this change in index that monitors the condition. The underlying theme of selectivity of the analyte measurand is presented as an important feature of SPR sensor technology and its deployment in the built environment. Lasers and camera's are vital to this sensor technology, the use of such instrumentation already employed within civil engineering and construction industries are examined. Advantages associated with this approach are discussed in terms of the phenomenon as a new applied science to the built and natural environment.

Unlike the infrastructure it monitors, sensor networks are subject to transient failures including data perturbations and data loss. This paper discusses the evaluation of sensor data using raw continuous readings from sensors that have been distributed pervasively through one academic building for almost 18 months. While the sensors monitor temperature, the results could have been produced by any sensor device. Data loss is due to the sensor device being unable to collect data at the requested frequency. This paper presents an analysis of the data loss to determine cause and identify solutions for mitigation of the problem in future sensor deployment. Primary causes of data loss are necessary reboots from application patches, and security issues.

Damage pattern recognition research represents one of the challenging stages in structural health monitoring. This is attributed to the fact that the process of damage detection is significantly affected by uncertainties in the damage features and how they propagate during the damage detection process. The challenge is also attributed to the vagueness in defining damage and the significant overlap between damage states. Several attempts have been performed by the research community to develop tools for damage detection using means of structural dynamics analysis such as modal update and wavelets. Other efforts have also been reported on damage recognition for several damage features using probabilistic and fuzzy logic techniques. This article introduces an integrated method for damage feature extraction and damage recognition using an optimal neural-wavelet module. The neural-wavelet module is used for damage feature extraction by recognizing the change in the energy of dynamic signals in the structure. Optimization methods are used to establish a classifier that can provide efficient damage pattern recognition. Design of the classifier is based on minimizing the error of classification of the neural-wavelet module. The classification error is optimized through changing parameters related to the architecture of the neural network including the number of layers and neurons per layer of the neural-wavelet module. A case study showing the ability of the proposed technique to detect and pattern damage in the ASCE benchmark structure is presented. It is suggested that such integration can provide efficient damage detection and recognition for accurate structural health monitoring.

On obstacle-cluttered construction sites, understanding the motion characteristics of objects is important for anticipating collisions and preventing accidents. This study investigates algorithms for object identification applications that can be used by heavy equipment operators to effectively monitor congested local environment. The proposed framework contains algorithms for three-dimensional spatial modeling and image matching that are based on 3D images scanned by a high-frame rate range sensor. The preliminary results show that an occupancy grid spatial modeling algorithm can successfully build the most pertinent spatial information, and that an image matching algorithm is best able to identify which objects are in the scanned scene.

Infrastructure spatial data, such as the orientation and the location of in place structures and these structures' boundaries and areas, play a very important role for many civil infrastructure development and rehabilitation applications, such as defect detection, site planning, on-site safety assistance and others. In order to acquire these data, a number of modern optical-based spatial data acquisition techniques can be used. These techniques are based on stereo vision, optics, time of flight, etc., and have distinct characteristics, benefits and limitations. The main purpose of this paper is to compare these infrastructure optical-based spatial data acquisition techniques based on civil infrastructure application requirements. In order to achieve this goal, the benefits and limitations of these techniques were identified. Subsequently, these techniques were compared according to applications' requirements, such as spatial accuracy, the automation of acquisition, the portability of devices and others. With the help of this comparison, unique characteristics of these techniques were identified so that practitioners will be able to select an appropriate technique for their own applications.

The business world is continuously changing due to the advances and developments in technology. Innovations in technology change all the industries and the way of performing business activities. E-Business (E-b) has created many advantages and opportunities for every industry. Construction is one of the most information-dependent industries. Construction companies (CCs) have to adopt the E-b applications in order to survive in business environment in the future. However, before entering into E-b, CCs should follow some basic steps in order to achieve a successful transformation. In this study, these necessary steps have been examined. An e-readiness assessment for CCs has been presented. Furthermore, an application of this assessment has been carried out among eight leading Turkish construction contractors that are operating within the international construction market. The main objective of this study was to determine whether these firms are entered into E-b world or ready for E-b transformation.

The electro-mechanical impedance (EMI) method is a relatively new nondestructive evaluation (NDE) method which uses the electro-mechanical coupling effect of piezoceramic Lead Zirconate Titanate (PZT) transducers to measure the force impedance of the structure. Due to the electro-mechanical coupling effect of the transducers, any changes in the mechanical impedance of the structure caused by the damage will affect the electrical impedance of the transducer. By comparing the impedance spectra of the damaged structure with the baseline, i.e., the impedance spectra for the pristine structure, the damage in the structure can be assessed. The quantity of the damage is assessed by a statistically calculated damage index, such as root mean square deviation or mean absolute percentage deviation or covariance change or correlation coefficient deviation. The EMI method has shown some advantages over the conventional NDE methods. However, it is not able to simultaneously identify the location and quantify the damage. This paper presents a technique integrating evolutionary programming and the EMI method to overcome this limitation. Essentially, the proposed technique first makes use of the EMI method to measure the variations of the electro-mechanical impedance of the structure. The damage is then identified by a system identification technique which is generally employed in the vibration-based method. Due to the numerous local optima in the search space, the traditional optimization strategies may not be able to find the correct solution. Evolutionary programming (EP) is then used as the system identification technique to find the global optimum. Thus, both the location and the quantity of the damage can be simultaneously identified. In order to enhance the integrated EP and EMI method, a fitness function, which can be generally applied to the other methods, is proposed to discriminate the variations caused by damages from the discrepancies caused by modelling errors. An experimental test is carried out on a cylindrical shell specimen to verify the damage detection results. The experiment demonstrated that both the location and the extent of damage can be simultaneously identified by the integrated EP-EMI method.

The Intelligent Job Site is becoming a reality as applications (e.g., RFID for materials tracking, laser scanning and GPS for surveying and layout) using sensors and mobile computing devices are being developed and deployed commercially. This creates an opportunity for workers to access sensors in an ad hoc manner as they move through a job site. However, re-tasking and re-use of sensor data in a dynamic setting presents significant challenges including ad hoc identification of sensors in a local environment, the generalization of sensor information, and the use of such dynamic info for decision support applications. All these tasks require coordinated advancement of a variety of information and communication technologies. To achieve a generalized approach to make use of local sensor data, this paper describes a three-layer architecture which abstracts functionality into three corresponding tiers: a layer for sensor communication that handles physical communication between devices; a middle-layer for data processing and abstraction of sensor data from specific devices; and a top layer for decision support applications. At each of the three tiers in the architecture the level of abstraction increases, allowing for development of decision support applications at the top level that are not directly tied to specific sensors or computing devices. This paper demonstrates the usefulness and versatility of the proposed three-tier architecture by describing two safety applications envisaged for the Intelligent Job Site.

This paper describes an approach to construct a numerical crane model in a computer-generated virtual world. A dual-crane scenario was used to demonstrate. The numerical crane model is divided into two sub-models: a manipulation model and a suspension model. The manipulation model is used to describe the relationship between the crane operations (the movement of each part of the crane) and crane status (the position and orientation of the crane). The suspension model includes the crane cables and rigging object. It can be used to analyze the dynamic behavior of the suspended object caused by the inertial forces during crane operation. To demonstrate the use of the sub-models, a prototype simulation system has been developed. The results show that the prototype system can sufficiently provide visualization details for simulating crane manipulation and cooperation.

Four dimensional (4D) construction management systems combine 3D models and their corresponding construction schedules to facilitate project management. Typical 4D models use a series of colors to present the statuses of construction progress. Having surveyed various existing 4D tools, it is evident that developers consider little about the selection of color schemes. These color schemes, however, may or may not be appropriate for visualizing 4D models. In this research, we consider the nature of scheduling information and the categories of colors to select color schemes for 4D models. After selecting eight color schemes, we performed an experiment to test these color schemes displayed on different media, including on desktop computer monitors, by projection and on paper. After testing ten users each with a different combination of 4D models and color schemes, we determined that one of the color schemes is most suitable for 4D models in terms of effectiveness, readability, and user satisfaction.

Inspections are inherent in many steps throughout the management life cycle of municipal infrastructure. Mobile technology has the potential to improve information capture and management for inspections allowing for easier access, review, and increased detail. A plethora of possible technology solutions do exist but with few comprehensive techniques available to industry for adoption and implementation assessment. This research project's primary deliverable was the development of a method for selecting various technology features for a given inspection type with a medium-sized municipality's information technology division serving as the research client. Six different infrastructure inspections, encompassing extensive contextual aspects and user requirements, were used in the development of an analysis framework. The framework, comprised of elements that segregate inspections into generic steps and corresponding information and data requirements, placed an emphasis on the contextual aspects that may influence the applicability of technology. The results are intended as input for formal usability evaluations to validate functional requirements.

This paper summarizes an ongoing project regarding the development of SimuSurvey, a computer-based surveyor training tool. Since survey instruments are costly, surveyor trainers (usually college instructors) oftentimes face a challenge in maintaining and providing high-quality instruments for the class, SimuSurvey is a computer-based simulator which is capable of visualizing and simulating surveying scenarios in a computer-generated virtual environment. Since SimuSurvey is designed for educational purposes, a comfortable and effective user interface that can support teaching and learning activities is important. However, designing a high-quality user interface that fulfills users' needs is a challenging task. In this study, a user-centered design process was employed. We found that this process can systematically determine user requirements, efficiently navigate through multiple design choices, and effectively improve the existing user interface.

In the event of natural and man-made disasters in urban areas, buildings are always being considered as one of the critical physical infrastructures (CPIs). Information regarding the building such as floor plans, emergency exit routes and building condition is highly valuable and critical to the first responders and rescue teams. However, as the experience of the 9/11 terrorist attack shows, access to accurate building information on site was limited and inefficient due to inappropriate and ineffective documentation management. To improve accurate building information access, sharing and collaboration efforts, on-site preservation of building information and local communication networking frameworks with sufficiently robust and redundant systems are vital and necessary. This paper presents the conceptual design of a building blackbox system that is equipped with disaster-survivable protections, wireless communication capabilities and a digital building database to support the decision-making process during and after disastrous events. This blackbox system aims at building an infrastructure of two-way communication between the building systems and the emergency response team over the enhanced mobile ad hoc space for collaboration (MASC) platform, providing real-time and critical information regarding building structural health, environmental conditions and personnel information.

SERCB (Seismic Evaluation of Reinforced-Concrete Building) is a computer software package used to estimate the seismic capacity of a building. Often long procedures are required to enter data collected from diverse sources. Therefore, it is important to design a user interface (UI) so users can work effectively and efficiently. In this research, a systematic evaluation method was developed. We first sampled 14 users from target user groups, and conducted usability tests. From the interview and observation of the users' behaviors in performing assigned tasks, we collected both qualitative and quantitative data. The usability problems of SERCB were qualitatively defined from interviews and observations. An equation was developed to quantitatively estimate the overall usability of this user interface.

An Augmented Reality (AR) application is essentially a platform that integrates the selected hardware components via their corresponding software interfaces. In the context of this research, a software interface is a piece of code implemented to establish communication channels between a hardware device and the AR application platform. The implementation of such an interface for each piece of hardware in an AR application requires a significant amount of time and coding effort. In all engineering and scientific applications of AR developed thus far, although they largely integrate and communicate with the same set of hardware components, the effort invested in implementing the required software interfaces has been repeatedly duplicated. The objective of the presented research has been to remedy this situation by designing and implementing an extensible software framework that allows application developers to communicate with typical AR hardware components. This paper describes the design of a software interface that enables generic communication with peripheral positioning and orientation devices that are typical components in all scientific and engineering AR applications.

This paper presents research that is investigating the requirements of an automated location-based methodology to rapidly identify and retrieve contextual project information on indoor and outdoor construction sites for supporting decision-making tasks of site personnel. The proposed approach to this retrieval task is the design and implementation of a dynamic user-viewpoint tracking scheme that can allow identification of construction entities visible in a user's field of view at any given time and location. For outdoor applications, a geo-referencing based algorithm has been developed using Global Positioning System (GPS) receivers and magnetic orientation tracking devices to successfully track user's dynamic viewpoint. For indoor applications, this research is studying the applicability of Wireless Local Area Networks (WLAN) for dynamic user position tracking. The objectives of this paper are to describe the overall methodology being designed as well as to describe the proof of concept experiments performed outdoors and indoors. The obtained results highlighted the potential of using location-aware technologies for rapidly detecting contextual objects in construction environments.

This paper describes the design of an outdoor Distributed Mixed Reality (DMR) system to support multi-user interaction of multi-users and virtual object manipulations in a construction simulation. The proposed DMR system is based on an interactive animation system of operating virtual cranes and extends previous work in a significant manner by considering engineering constraints. Our design integrates a Head-Mounted Display, a GPS receiver, a 3D motion sensor, and a portable computer to carry out a construction simulation which can be run in the outdoors. We describe and evaluate the system design challenges and possible solutions for simulating multi-user collaborative construction activities within the DMR environment. Several issues related to tracking and registration, modeling, user interaction, and mobile networking are discussed. The proposed system prototype is demonstrated using a case study which simulates the deck rehabilitation project of a bridge. Using this system, two users can collaborate to replace a section of the bridge deck by operating two virtual cranes and communicating with each other.

Ad-hoc networks are self-organized wireless networks. This paper presents a new approach to investigate problems related to deploying ad-hoc wireless networks for supporting communication and onsite data collection. Several modes of communication which are common in field applications are considered including location information, text messaging, voice and video communications, and file transmission. A prototype system is implemented for testing these modes based on available ad-hoc network protocols and using mobile devices. Furthermore, we introduce a new protocol based on clustering to improve data accessibility and present the simulated results of the performance of this protocol using different scenarios of ad-hoc clusters. The simulation shows the impact of the area size, wireless range, number of nodes, and node speed on data accessibility.

This paper presents the development and testing of the Virtual Construction Simulator (VCS), a 4D CAD generation prototype which allows a user to develop a construction schedule by interacting directly with the 3D building model. The prototype application was developed in a 3D game engine interface. The VCS is developed to allow a user to group 3D components into construction assemblies, sequence the assemblies, and review the 4D model for the project. The VCS interface was assessed through a classroom exercise where 10 student groups developed construction schedules for a portion of a project. 5 of the student groups used the VCS application and 5 groups used a traditional 4D CAD modeling application for reviewing a schedule generated in a CPM application. The VCS allowed the groups to be more focused on the 3D model during the schedule process and aided in the identification of more innovative ideas.

Recently, a new generation of finite-element-based predictive models capable of handling coupled multiple transport mechanisms such as diffusion, advection and electrical coupling were developed to evaluate the durability of concrete structures exposed to chloride-bearing environments. These tools are destined to replace the simplified approach based on Fick's second law. This paper presents a sophisticated finite-element ionic transport software, called STADIUM® that reliably predicts time to initiate corrosion and the multiple alterations that a structure can sustain throughout its service-life. The model is based on a multiionic approach that considers eight ionic species and the chemical interactions between the paste and the pore solution of cementitious materials. A test case of a parking structure shows the benefit of the proposed modeling approach compared to traditional analysis.