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Select this Article		Information Retrieval from Civil Engineering Repositories: The Importance of Context and Granularity Peter Demian and Panos Balatsoukas Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000229 Posted ahead of print 30 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Information about the design and construction of buildings can be structured in a particular way. This is especially correct given the increasing complexity of building product models and the emergence of Building Information Models with project documents linked to them. In addition, engineers usually have distinct information needs. Research shows that engineers working with Building Information Models place particular importance on the understanding of retrieved content before using it or applying it, and that exploration of context is essential for this understanding. Both these factors (the nature of engineering content and the information needs of engineers) make general information retrieval techniques for computing relevance and visualizing search results less applicable in civil engineering information retrieval systems. This paper argues that granularity is a fundamental concept that needs to be considered when measuring relevance and visualizing search results in information retrieval systems for repositories of building design and construction content. It is hypothesized that the design of systems with careful regard for granularity would improve engineers' relevance judgment behaviour. In order to test this hypothesis, a prototype system, called CoMem‐XML, was developed and evaluated in terms of the time needed for users to find relevant information, the accuracy of their relevance judgment and their subjective satisfaction with the prototype. A user study was conducted where test subjects were asked to complete tasks using various forms of the prototype, to complete a satisfaction questionnaire, and to be interviewed. The findings show that users perform better and are more satisfied when the search result interface of the CoMem‐XML system presents only relevant information in context. On the other hand, interfaces that present the retrieved information out of context (i.e. without highlighting its position in the parts hierarchy) are less effective for participants to judge relevance.

Select this Article		Improved Genetic Algorithm for Finance‐Based Scheduling Anas Alghazi, Ashraf Elazouni, and Shokri Selim Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000227 Posted ahead of print 26 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Currently, the Genetic Algorithm (GA) technique has been used in finance‐based scheduling to devise Critical Path Method (CPM) schedules exhibiting cash flows of periodical finance needs below preset cash constraints. The chromosomes of the schedules which violate this condition are referred to as finance‐infeasible chromosomes. Infeasibility related to finance is peculiar to finance‐based scheduling problems. In scheduling problems, chromosomes that are infeasible based on precedence relationships are typically penalized. This paper introduces a repair algorithm for the finance‐infeasible chromosomes generated within the GA systems. The repair algorithm identifies the periods exhibiting finance needs that exceed the constrained cash, calculates the amounts of finance needs above the constraints, identifies the ongoing activities, selects randomly an activity for delaying its start time, determines the impact of the delay on the finance needs, and repeats the procedure till finance feasibility is attained. A 13‐activity project was used to demonstrate the proposed repair algorithm. The performance of the repaired‐chromosome GA system is evaluated through comparison against replaced‐chromosome and penalized‐chromosome GA systems using a fairly big project of 210 activities. Finally, the results which were validated using the Integer Programming technique proved the superior performance of the repaired‐chromosome GA in terms of the computational cost and quality of solutions.

Select this Article		Parametric Performance Evaluation of Wavelet‐Based Corrosion Detection Algorithms for Condition Assessment of Civil Infrastructure Systems Mohammad Reza Jahanshahi and Sami F. Masri Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000225 Posted ahead of print 26 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Corrosion is a crucial defect in structural systems that can lead to catastrophic effects if neglected. Current structure inspection standards require an inspector to visually assess target structure's conditions. A less time‐consuming and inexpensive alternative to current monitoring methods is to use a robotic system that can inspect structures more frequently and perform autonomous damage detection. The feasibility of using image processing techniques to detect corrosion in structures has been acknowledged by leading experts in the field; however, there has not been a systematic study to evaluate the effect of different parameters on the performance of vision‐based corrosion detection systems. This study evaluates several parameters that can affect the performance of color wavelet‐based texture analysis algorithms for detecting corrosion. Furthermore, an approach is proposed to utilize the depth perception for corrosion detection. The proposed approach improves the reliability of the corrosion detection algorithm. The integration of depth perception with pattern classification algorithms, which has never been reported in published studies, is part of the contribution of the current study. Several quantitative evaluations are presented to scrutinize the performance of the investigated approaches.

Select this Article		Data Fusion of Real‐Time Location Sensing (RTLS) and Physiological Status Monitoring (PSM) for Ergonomics Analysis of Construction Workers Tao Cheng, Giovanni C. Migliaccio, Jochen Teizer, and Umberto C. Gatti Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000222 Posted ahead of print 12 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Previous research and applications in construction resource optimization have focused on tracking the location of material and equipment. There is a lack of studies on remote monitoring for improving safety and health of the construction workforce. This paper presents a new approach for monitoring ergonomically safe and unsafe behavior of construction workers. The study relies on a methodology that utilizes fusion of data from continuous remote monitoring of construction workers' location and physiological status. To monitor construction workers activities, the authors deployed non‐intrusive real‐time worker location sensing (RTLS) and physiological status monitoring (PSM) technology. This paper presents the background and need for a data fusion approach, the framework, the test bed environment, and results to some case studies that were used to automatically identify unhealthy work behavior. Results of this study suggest a new approach for automating remote monitoring of construction workers safety performance by fusing data on their location and physical strain.

Select this Article		A Decision Support System for Railway Track Maintenance and Renewal Management Hakan Guler Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000221 Posted ahead of print 12 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract This paper describes a decision support system approach for railway track maintenance and renewal management system to analyse the track components and to suggest methods for helping the track managers and engineers decide when maintenance is necessary and when is the best time for renewal. In this study, interviews with track maintenance experts, a national survey and a comprehensive literature survey were used to develop the purposed decision support system. The developed decision support system includes some decision rules. On the base of these decision rules, the analyses were realized into some stages and successful results were obtained. The developed decision support system proved that it is possible to develop planned maintenance and renewal management systems by using advanced computer and measuring systems instead of corrective maintenance and renewal.

Select this Article		Finding All Pairs Shortest Path for a Large‐Scale Transportation Network Using Parallel Floyd‐Warshall and Parallel Dijkstra Algorithms Anu Pradhan and G. (Kumar) Mahinthakumar Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000220 Posted ahead of print 12 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Parallel computing has become a powerful approach to solve large‐scale computing‐intensive transportation problems when decisions have to be made in real‐time. A frequently encountered transportation problem is the ‘shortest path problem’ that is finding the shortest path between any two nodes in a transportation network. For large transportation networks encountered in major metropolitan areas, such problem can be computationally demanding especially if shortest paths between all the nodes in the network need to be updated dynamically (e.g., evolving traffic conditions). In such situation, one may wish to harness parallel computing to solve such problem. However, the parallel implementations of commonly used shortest path algorithms are computationally demanding due to the inherent sequential nature of the search process used by the algorithms. This paper describes parallel implementations and performance analyses of two prominent graph algorithms (i.e., Floyd‐Warshall and Dijkstra) used for finding the all‐pairs shortest path for a large‐scale transportation network. The results indicate that a multilevel parallel implementation that combines MPI (Message Passing Interface) with shared memory threads (OpenMP or pthreads) is effective in solving these problems on moderate number of SMP (symmetric multiprocessor) nodes. The authors have also derived the computational time for the different parallel implementations of these two graph algorithms.

Select this Article		Feedforward Analysis for Shield‐Ground System Lieyun Ding, Fan Wang, Hanbin Luo, Minghui Yu, and Xianguo Wu Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000219 Posted ahead of print 12 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Ground surface settlement is an important measurement in identifying potential damages for shield tunnelling. Identifying the relationship between shield parameters and the resulting settlement is of vital importance to the reasonable adjustment of the shield parameters so as to control settlement development. However, many other factors, besides the shield parameters, jointly affect settlement, which makes shield‐ground interaction complicated. Therefore, a better method is necessary for extracting the shield‐ground relationship for the purpose of steering shield tunnelling. This paper proposes a method that incorporates smooth relevance vector machine (sRVM) and particle swarm optimization (PSO) for shield steering concerning settlement control. Firstly, smooth relevance vector machine with adaptive Gaussian kernel function is used to establish the relationship between the identified factors and the settlement. Particle swarm optimization is then applied to identify the appropriate kernel parameters. Then optimal shield parameters are searched based on the established relationships. A slurry shield‐driven tunnel (the Jiyuqiao‐Jianghan Road Tunnel) is conducted to validate the method. The results evaluate the potential as well as some limitations of the proposed method, which attempts to offer an alternative means for feedforward control of the shield steering.

Select this Article		A Multi‐Agent System to Simulate the Risk Allocation and Cost Sharing Process in Construction Projects Kivanc Karakas, Irem Dikmen, and M. Talat Birgonul Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000218 Posted ahead of print 10 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Multi‐agent systems (MAS) consist of several autonomous entities, called agents, which interact with each other to either fulfill their own interests (competition) or reach a common goal (cooperation). In MAS, negotiation is the key form of interaction that enables groups of agents to arrive at a mutual agreement regarding some belief, goal or plan. The aim of this study is to develop a MAS that simulates the negotiation process between parties (mainly, contractor and client) about risk allocation and sharing of cost overrun in construction projects. MAS has been developed using three different negotiation protocols, namely, Time Dependent Concession, Zeuthen's Strategy and Zeuthen's Strategy with Bayesian Learning. Sensitivity analysis has been carried out to test the impact of reservation value, first offer value and negotiation protocol on the settlement amounts. The model has also been tested on three hypothetical cases. Results show that mainly the reservation value determines the settlement amount of the negotiation. The developed system can be used by decision‐makers to understand how the risks and associated costs are shared between parties under different scenarios regarding contract conditions, short and long term objectives of parties, level of knowledge about actual sources of cost overrun and to predict the potential outcomes of a negotiation process.

Select this Article		An Integrated 3D Web Application for Structural Analysis Software as a Service Javier Gracia, Ph.D. and Eduardo Bayo, M. ASCE Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000217 Posted ahead of print 10 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Internet has increased its capacities and possibilities exponentially since its inception. This evolution has been possible due to new standards and technologies like Web services. Structural analysis software has benefited from them supplying a new set of applications that provide highly intensive computational tasks in Web servers. However, recent and future improvements in Internet will enable the development of a new type of structural analysis application fully integrated in Web browsers, and not only deployed as Web services. This type of Internet application is formally known as Web Application. In this paper we present the development of a 3D Web Application for structural analysis, hereafter known as Structural Analysis Software as a Service, which is applied to 3D lattice girder structures. Latest cutting‐edge Internet technologies are used to address fundamental issues inherent to structural analysis software such as visualization, interaction, and structural analysis. Specifically, WebGL API, part of the new HTML5 standard, is used to solve the visualization and interaction issues of the proposed application. This prototype only requires an Internet connection and an updated browser that supports these new standards. No additional plug‐in or virtual machine interpreter is needed, thus, platform independence is guaranteed.

Select this Article		Development of Improved 4D CAD System for Horizontal Works in Civil Engineering Project Leenseok Kang, Jaeho Pyeon, M. ASCE, Hyounseok Moon, Changhak Kim, and Minsu Kang Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000216 Posted ahead of print 10 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract One of the purposes of using 4D CAD system is to express numeric construction schedule data into a visual format. While existing 4D CAD systems are appropriate for building projects composed of vertical schedule progress and manufactured elements, the basic functions of those systems have limitations when directly applied to a civil engineering project, such as highway and railway facilities. Such projects include horizontal works and their activities are carried out according to the elements of natural topography. This study attempts to develop a 4D CAD engine that supports analysis of the 4D objects for horizontal elements including a visual simulation of a cutting and filling status of an earthwork section in civil engineering projects. The system uses integrated information management techniques by using WBS for simulating 4D objects for each level. The developed engine includes new functions for visualizing work schedule and activity progress in highway and railway project with horizontal earthwork. Finally, to improve the practical applicability of 4D CAD system, a new method for visualizing risk analysis data is suggested for future studies.

Select this Article		Energy Modeling System Using Building Information Modeling (BIM) Open Standards Hyunjoo Kim and Kyle Anderson Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000215 Posted ahead of print 10 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract There is an urgent need in the architecture, engineering, and construction industry for new programs and methods of producing reliable energy simulations using building information modeling (BIM) technology. Current methods and programs for running energy simulations are not very timely, difficult to understand, and lack high interoperability between BIM and energy simulation software. It is necessary to improve on these drawbacks as design decisions are often made without the aid of energy modeling leading to the design and construction of non‐optimized buildings with respect to energy efficiency. The goal of this research project is to develop a new methodology to produce energy estimates from a BIM model expeditiously and to improve interoperability between the simulation engine and BIM software. In the proposed methodology, the extracted information from a BIM model is compiled into an input file and run in a popular energy simulation program, DOE‐2 (U.S. Department of Energy), on an hourly basis for a desired time period. The case applied in this paper showed that the application of this methodology can be used to quickly provide energy simulations from BIM models. With the aid of an easy to run and easily understood energy simulation methodology, designers will be able to make more energy conscious decisions during the design phase and as changes in design requirements arise.

Select this Article		Automated Real‐Time Monitoring System to Measure Shift Production of Tunnel Construction Projects Kamal Ranaweera, Janaka Ruwanpura, and Siri Fernando Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000199 Posted ahead of print 22 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract The productivity of a tunnel construction project can deviate from the predicted plan due to many factors, such as equipment failure, weather conditions, unexpected soil characteristics, etc. Early detection of such deviations can help management teams to reallocate resources and take necessary actions to maximize the productivity. The real‐time monitoring of actual productivity would yield tremendous information towards this end, but such monitoring is difficult, especially with remote construction sites. Therefore, the common practice has been to periodically obtain manually generated aggregated productivity reports from sites. These aggregated reports are not available to both site and office management in real time and may lack detailed information. To avoid these drawbacks, the research presented in this paper proposes an automated tunnel construction monitoring system to measure the productivity of the tunnel construction in terms of shift production (metres/shift). This system computes the shift production in real time using time‐lapsed images of a tunnel construction site and provides instant access to these reports via a secure web portal. The web portal also shows video clips of remote site activities. The reports generated by the system can be verified without obtaining any additional input from the sites. This paper describes the design of the proposed system in detail, including its principles, image processing algorithms, system architecture, and user interface details. System operation is illustrated using real examples. Validation results are presented and analyzed at the algorithmic level as well as at the system level.

Select this Article		Reasoning about Building Systems and Content to Support Vulnerability Assessment in Building Emergencies Fernanda Leite and Burcu Akinci Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000214 Posted ahead of print 17 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Vulnerability assessment serves to identify vulnerabilities, develop responses and drive the risk management process. In identifying vulnerabilities, it is fundamental to identify and rank critical assets, which include vital systems, facilities, processes, and information necessary to maintain continuity of service. In emergencies in the facility management domain, first responders typically search for critical assets, both related to business continuity and value to the organization. This paper presents a formalized approach to reason about building systems and content to support vulnerability assessment in building emergencies caused by failures in building systems (e.g. sprinkler line leak, power outage). The developed reasoning approach enables a first responder to perform flexible searches, as well as prioritize critical spaces and pieces of equipment that need to be protected in an emergency, by leveraging existing building and content representations found in building information models (BIM). This approach targets retrieving and prioritizing vulnerable content using a faceted classification based approach. The faceted‐retrieval mechanism was tested for precision and recall in retrieving vulnerable content in two scenarios with ten experts. Results show increased precision and recall (98% and 92%, respectively) when all facets were used in the search. These results demonstrate that the faceted‐retrieval mechanism more effectively retrieves content that need to be protected in building emergencies.

Select this Article		A Multi‐Objective Evolutionary Approach to Optimal Reservoir Operation Andre Schardong, A. Vasan, and Slobodan P. Simonovic, F. ASCE Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000213 Posted ahead of print 17 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents an application of Multi‐objective Differential Evolution (MoDE) algorithm for the optimal operation of a complex multipurpose reservoir system. The developed algorithm (MoDE) is compared to Genetic Algorithm (NSGA II) using a set of common test problems and the case study. The case study includes part of a complex water supply system located in Southwest Brazil that provides water for almost 20 million people in Sao Paulo Metropolitan Area (SPMA). The objectives of the case study include minimization of demand shortage (the difference between demand for water and available water supply), maximization of water quality (or minimization of the deviation from the water quality standards) and minimization of pumping cost. MoDE is applied to the case study using two inflow scenarios: (i) a drought period with inflows below historical average; and (ii) a wet period with inflows above historical average. Multi‐objective analysis is done by comparing two pairs of objective functions: minimization of demand shortage versus minimization of pumping cost and minimization of demand shortage versus minimization of the deviation from water quality standards. The constraints for the analysis are reservoir capacity, tunnels and channel limitations and minimum downstream flow for all reservoirs. The proposed MoDE algorithm is outperforming NSGA‐II as it converges closer to, and provides better spread coverage of the true Pareto front.

Select this Article		Supervised Classification of Basaltic Aggregate Particles Based on Texture Properties Lilian Tais de Gouveia, Guilherme Ferraz de Arruda, Francisco Aparecido Rodrigues, Luciano Jose Senger, and Luciano da Fontoura Costa Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000212 Posted ahead of print 17 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract The strength and durability of materials produced from aggregates (e.g. concrete bricks, concrete, and ballast) are critically affected by the weathering of the particles, which is closely related to their mineral composition. It is possible to infer the degree of weathering from visual features derived from the surface of the aggregates. By using sound pattern recognition methods, we show that the characterization of the visual texture of particles, performed by using texture‐related features of gray‐scale images, allows the effective differentiation between weathered and non‐weathered aggregates. The selection of the most discriminative features is also performed by taking into account a feature ranking method. The evaluation of our methodology in presence of noise suggests that it can be used in stone‐quarries for automatic detection of weathered materials.

Select this Article		Automated and Efficient Method for Extraction of Tunnel Cross‐Sections Using Terrestrial Laser Scanned Data Soohee Han, Hyungsig Cho, Sangmin Kim, Jaehoon Jung, and Joon Heo Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000211 Posted ahead of print 17 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract An automated and efficient method for extraction of tunnel cross‐sections using Terrestrial Laser Scanner (TLS) data is presented. In this process, a 3‐dimensional (3D) point cloud acquired from the TLS is projected onto a horizon plane, converted to a 2‐dimensional (2D) planar image, and skeletonized to estimate the tunnel centerline. Stations from which cross‐sections are extracted are estimated from that centerline, which is vectorized and smoothed for better estimation. From those stations, cross‐section planes are estimated, and point groups surrounding the planes are extracted. Using these point groups, the azimuth angles of the cross‐section planes are adjusted, and the final cross‐sections are generated by projecting the nearby points to the adjusted planes. The performance of the proposed method was evaluated by applying it to a real tunnel and comparing the results with those from a conventional method that uses a total station. In the results, the cross‐sections were extracted at the stations corresponding to the conventional method. The proposed method proved itself to offer advantages including detailed description and improved surveying and data processing efficiencies.

Select this Article		Algorithms for Generating Three‐Dimensional Aggregates and Asphalt Mixture Samples by the Discrete Element Method Dong Zhang, Xiaoming Huang, and Yongli Zhao Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000210 Posted ahead of print 17 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract An algorithm for generating three‐dimensional aggregates was developed first in this study. This algorithm can model the various shapes, sizes and angularity of the coarse aggregates. The shapes, sizes and angularity of the generated aggregates can be correlated to those of actual aggregates. Then, algorithms were developed to model the coarse aggregate gradation accurately and place the coarse aggregates randomly within the sample. Finally, algorithms were developed to generate the asphalt mastic. The triaxial compression test of the discrete element sample of the asphalt mixture with the nominal maximum aggregate size of 16 mm was simulated to predict its dynamic modulus. The results indicate that the discrete element model generated using the algorithms developed in this paper can predict the mixture modulus across a range of loading frequencies.

Select this Article		Three‐Dimensional Simulation Parameters for 90° Open Channel Bend Flows A. S. Ramamurthy, S. S. Han, and P. M. Biron Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000209 Posted ahead of print 17 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Sharp open‐channel bend flows are highly three‐dimensional due to the combined effects of secondary flow, large free surface variations, and flow separation along the inner bend wall. A comprehensive analysis was carried out to determine the best modeling parameters to study the open channel sharp bend flow. Comparison of the simulation results were made from two commercial codes (PHOENICS and Fluent), three turbulence models (k‐ϵ RNG, RSM and LES), two flow domain representations (Cartesian and Body‐Bitted Coordinates grids) and three water surface treatments (rigid lid, porosity and VOF). Based on a comparison with experimental data, the best results were obtained with Fluent using the Reynolds stress model (RSM) and the volume of fluid (VOF) approach. The adequate representation of counter‐rotating secondary flow cells in the channel downstream of the bend requires both the appropriate treatment of the channel free surface and a turbulence model that can resolve the anisotropy of turbulence.

Select this Article		A Self‐Adaptive Differential Evolution Algorithm Applied to Water Distribution System Optimization Feifei Zheng, Aaron C. Zecchin, and Angus R. Simpson Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000208 Posted ahead of print 17 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Differential evolution (DE) is a relatively new technique that has recently been used to optimize the design for water distribution systems (WDSs). Several parameters need to be determined in the use of DE, including: population size, N; mutation weighting factor, F; crossover rate, CR and a particular mutation strategy. It has been demonstrated that the search behavior of DE is especially sensitive to the F and CR values. These parameters need to be fine‐tuned for different optimization problems as they are generally problem‐dependent. A self‐adaptive differential evolution (SADE) algorithm is proposed to optimize the design of WDSs. Three new contributions are included in the proposed SADE algorithm: (i) instead of pre‐specification, the control parameters of F and CR are encoded into the chromosome of the SADE algorithm and hence are adapted by means of evolution; (ii) F and CR values of the SADE algorithm apply at the individual level rather than the generational level normally used by the traditional DE algorithm; and (iii) a new convergence criterion is proposed for the SADE algorithm as the termination condition, thereby avoiding pre‐specifying a fixed number of generations or computational budget to terminate the evolution. Four WDS case studies have been used to demonstrate the effectiveness of the proposed SADE algorithm. The results obtained show that the proposed algorithm exhibits good performance in terms of solution quality and efficiency. The advantage of the proposed SADE algorithm is that it reduces the effort required to fine‐tune algorithm parameter values.

Select this Article		Automated Progress Monitoring Using Unordered Daily Construction Photographs and IFC‐Based Building Information Models Mani Golparvar‐Fard, Feniosky Peña‐Mora, and Silvio Savarese Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000205 Posted ahead of print 11 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Accurate and efficient tracking, analysis and visualization of as‐built (actual) status of buildings under construction are critical components of a successful project monitoring. Such information directly supports control decision‐making and if automated, can significantly impact management of a project. This paper presents a new automated approach for recognition of physical progress based on two emerging sources of information: (1) Unordered daily construction photo collections, which are currently collected at almost no cost on all construction sites; (2) Building Information Models (BIMs), which are increasingly turning into binding components of Architecture/Engineering/Construction contracts. First, given a set of unordered and uncalibrated site photographs, an approach based on structure‐from‐motion, multi‐view stereo, and voxel coloring and labeling algorithms is presented which calibrates cameras, photo‐realistically reconstructs a dense as‐built point cloud model in 4D (3D + time), and traverses and labels the scene for occupancy. This strategy explicitly accounts for occlusions and allows input images to be taken far apart and widely distributed around the environment. An IFC‐based (Industry Foundation Class) BIM is subsequently fused into the as‐built scene by a robust registration‐step and is traversed and labeled for expected progress visibility. Next, a machine learning scheme built upon a Bayesian probabilistic model is proposed that automatically detects physical progress in presence of occlusions and demonstrates that physical progress monitoring at schedule activity‐level could be fully automated. Finally, the system enables the expected and reconstructed elements to be explored with an interactive, image‐based 3D viewer where deviations are automatically color‐coded over the IFC‐based BIM. To that extent, the underlying hypotheses and algorithms for generating integrated 4D as‐built and as‐planned models plus automated progress monitoring are presented. Experimental results are reported for challenging image datasets collected under different lighting conditions and severe occlusions from two ongoing building construction projects. This marks the presented model to be the first probabilistic model for automated progress tracking and visualization of deviations that incorporates both as‐planned models and unordered daily photographs in a principled way.

Select this Article		A Computer Program for Multi‐Model Reliability and Optimization Analysis M. Mahsuli and T. Haukaas Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000204 Posted ahead of print 11 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract A computer program is developed to carry out reliability and optimization analysis with many inter‐connected probabilistic models. The program is freely available online and it contains a library of versatile models. The user can also implement new models—without any recompilation of the program—by several means, including a powerful scripting option. Other novel features include a comprehensive parameterization that facilitates flexible and effective model communication, and the computation of direct‐differentiation response sensitivities in multi‐model analysis. The new program has already been successfully employed for regional risk analysis with thousands of model objects and hundreds of random variables. This paper presents the software architecture and a multi‐model example of a structure that is modeled in an external finite element program and subjected to multiple hazards, damage, and long‐term deterioration.

Select this Article		An IFC‐Based Framework to Move beyond Individual Building Elements Towards Configuring Higher Level Prefabrication Alireza Khalili and D. K. H. Chua, Associate Professor, M. ASCE Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000203 Posted ahead of print 11 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Prefabrication is a form of industrialization that transfers some stages of the construction project from fields to an off‐site production facility. The most widely‐used form of prefabrication in construction is the use of prefabricated individual building elements, where a particular part or form is repeated many times. However, the benefits to the construction project may be increased by moving beyond prefabrication of individual building elements toward configuring higher level of prefabrication. In this paper, an IFC‐based system is developed to configure groupings of precast elements for a prefabricated building to minimize the total number of components so as to reduce the production, transportation and installation cost. The framework uses 3D CAD software that is compatible with IFC. Geometrical and topological relationships of elements are extracted from IFC and modeled as a Graph Data Model (GDM). The system performs analysis on the graph model based on the attributes of the building elements to generate all possible configurations for precasting. Constructability rules are applied to reduce the solutions to feasible configurations. The functionality of the developed framework is verified by considering an illustrative example of a residential building. Results showed that applying the new configurations of precast components can contribute up to 15% reduction in the total cost compared to traditional elemental approach.

Select this Article		A Computational‐Based Approach to Estimating Travel Demand in Large‐Scale Microscopic Traffic Simulation Models Shan Huang, Adel W. Sadek, A. M. ASCE, and Liya Guo Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000202 Posted ahead of print 16 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract The increased interest in the development and application of large‐scale or regional micro‐simulation transportation models has brought to the forefront the challenges associated with estimating the dynamic demand information needed to run such models. This paper develops a computational‐based approach for estimating or adjusting dynamic origin‐destination matrices for regional micro‐simulation models based on hourly traffic counts. The proposed approach, while based on Genetic Algorithms (GA), includes a special module, called Plan Analyzer, to guide the search process in an intelligent way. This results in a customized algorithm for the problem that can be regarded as an example of a Guided Genetic Algorithm (GGA). To cut down on execution time, a distributed implementation of the algorithm is adopted, and several software design procedures are developed to deal with the demanding memory requirements of the problem. To demonstrate the effectiveness of the algorithm, the Transportation Analysis and Simulation System (TRANSIMS) model, a micro‐simulation platform designed for regional simulations, is used to model two test networks, a synthetic grid network and a realistic regional model of Chittenden County, Vermont. The GGA is then utilized to estimate the dynamic demand for those two models, based on hourly traffic count information. The results clearly demonstrate the effectiveness of the GGA in dramatically reducing the average absolute error (AAE) between the simulated and field counts, and in closely estimating the “true” demand, which was known in this research by virtue of how the case studies were designed. The results also show that the developed GGA significantly outperforms standard GAs.

Select this Article		Document Discourse for Managing Construction Project Documents Mohammed Al Qady and Amr Kandil, M. ASCE Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000201 Posted ahead of print 16 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract Several important aspects characterize construction project documents. Large amounts of documents are produced in construction projects. The majority of the documents are unstructured textual documents. The production of documents is a gradual process that extends over the duration of the project. Documents, as information carriers, are an important repository of project knowledge. Project information is recorded, disputed, revised and reiterated in various successive documents producing links between these documents and creating groups of semantically related documents within the project corpus. Despite the difficulties imposed on document management efforts by these characteristics, an electronic document management (EDM) approach must take into account these features in order to successfully manage project documents. In this study, a prototype electronic document management system (EDMS) that capitalizes on the various aspects that characterize project documents is presented. The system is based on the document discourse concept which recognizes the semantic relations between groups of documents. The system also employs a text analysis feature which was evaluated for accuracy of classification based on document discourse and produced satisfactory results. The prototype system was evaluated using expert review. The main finding of the review recommends implementation of document discourse management as a module of an integrated project management system to achieve the best and most practical application.

Select this Article		Integration of Artificial Neural Networks with Radial Basis Function Interpolation in Earthfill Dam Seepage Modeling Vahid Nourani and Ali Babakhani Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000200 Posted ahead of print 16 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract In this study, the RBF (Radial Basis Function) spatial interpolation method was used to estimate the water potential heads through an earthen dam. Multiquadric (MQ) function was used for discretizing the seepage governing partial differential equation and related boundary conditions. The function contains a shape coefficient of c which takes an important role in the model calibration. Therefore at first, the coefficient of c was optimized via Hardy and cross validation methods and then by employing the optimal c (c _opt , two scenarios of the modeling with and without considering the internal conditions were provided to and the results were compared with the results of Finite Difference Method (FDM). In the next step, the Artificial Neural Network (ANN) was used for handling non‐linear time variability of the phenomenon to cope with the limitations of FDM and RBF methods in temporal modeling. Thus by training neural networks for the piezometers located in the core, the water potential time series were predicted and their results were imposed to the RBF method as the internal conditions along with the boundary conditions for spatial‐temporal modeling of the water heads. Finally, the assumed time‐invariant inherency of the c was confirmed by the cross validation method. The results show that there is not a notable time variation in time series of the c_opt and therefore it can be concluded that the value of shape coefficient in MQ formulation generally depends on the problem geometry rather than the temporal variation of the boundary conditions.

Select this Article		3D Visualisation of Traffic‐Induced Air Pollution Impacts of Urban Transport Schemes El‐Said M. Zahran, Martin J. Smith, and Lloyd D. Bennett Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000198 Posted ahead of print 14 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract The negative impacts of urban traffic growth are well known: congestion, increased air pollution, more traffic noise, etc. Humans can readily see traffic congestion, and can hear traffic noise, but inevitably they are much less aware of odourless, invisible, silent air pollution. Therefore, quite naturally people, whether the general public or transport professionals, struggle to visualise air pollution from traffic, and will find it particularly difficult to visualise changes in air pollution levels resulting from changes in traffic conditions due to the implementation of various urban transport schemes. Hence there is always a risk of the air quality impacts of potential urban transport schemes being under‐appreciated. Therefore, this paper contributes to the knowledge by devising a new 3D visualisation approach for modelled air quality before and after the implementation of potential urban transport schemes. Using the Dunkirk area of the City of Nottingham in the UK as a case study, research has been undertaken to integrate an air pollution dispersion model for the pollutant NO₂ with a 3D digital city model. The modelled NO₂ concentrations, before and after the implementation of an urban transport scheme, were represented in the 3D city model at various heights above the ground: firstly, as 3D point shapes; secondly, as 3D planar surfaces; and finally, as 3D volumetric clouds. The 3D volumetric clouds approach used the analogy of people's perceptions of grey clouds in the sky as representing undesirable weather, and hence provided an intuitive 3D visualisation of all the modelled NO₂ concentrations, at and above the ground surface, in a single 3D virtual scene. Benefits have been identified in enhancing the level of understanding of the pollution dispersion using this new approach to visualisation. This has allowed the visualisation process to be used in the development of future traffic scenarios that could be used to alter the design of a proposed transport scheme in order to increase its air quality benefits. This 3D visualisation approach was found to be applicable to other transport schemes in different parts of the City of Nottingham.

Select this Article		Predicting Disputes in Public‐Private Partnership Projects: Classification and Ensemble Models Jui‐Sheng (Rayson) Chou, P.E., Ph.D. and Chieh Lin Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000197 Posted ahead of print 14 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract Proactively forecasting disputes in the initiation phase of public‐private partnership (PPP) projects can considerably reduce the effort, time and cost of managing potential claims. This comprehensive study compared classification models for PPP project dispute problems. Performance comparisons included four machine learners, four classification and regression trees, two multivariate statistical techniques, and combinations of techniques that have performed best according to a historical database. Experimental results indicate that ensemble technique (i.e., SVM+ANNs+C5.0) provides better cross‐fold prediction accuracy (84.33%) compared to all other individual classification models. Specifically, SVM is the best model for classifying dispute propensity in terms of overall performance measures. This study demonstrates the efficiency and effectiveness of data mining techniques for early prediction of dispute propensity in PPP projects pertaining to public infrastructure services. The modelling results provide proactive‐warning and decision‐support information needed for managing potential disputes before disputes occur.

Select this Article		The Facility Management Handover Model View E. William East, Ph.D., P.E., F. ASCE, Nicholas Nisbet, and Thomas Liebich Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000196 Posted ahead of print 14 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract Current specifications for facility handover information require contractors to produce and deliver a set of documents that provide little practical value to the facility manager. Facility managers begin their duties by rekeying the information found in these handover documents. This paper describes the Facility Management Handover (FM) Model View Definition (MVD), an open‐standard information exchange format that may replace current construction handover document requirements. The work was accomplished in conjunction with three buildingSMART chapters to ensure the widest possible international acceptance. The specification of the underlying Industry Foundation Class (IFC) model with required business rules for use in the United States is called the Construction‐Operations Building information exchange (COBie) format. Procedures used to test software production and consumption of COBie were developed. Use of COBie has now been documented in several case studies.

Select this Article		IFC‐Based Product Catalogue Formalization for Software Interoperability in the Construction Management Domain K. Umut Gökçe, Ph.D., H. Ufuk Gökçe, Ph.D., and P. Katranuschkov, Ph.D. Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000194 Posted ahead of print 12 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract Interoperability of the heterogeneous applications used in the domain of construction management can be best achieved by using generalized and standardized representations of the needed product data together with the data from product catalogues, thereby enabling faster and better management and decision‐making in terms of cost efficient building element selection. However, even though various solution approaches have been proposed in the last years, a general approach based on an acknowledged building information model standard is still missing. In this paper, a new product catalogue structure complying with the data schema of the IFC standard is presented. It allows for coherent integration of product and cost information, helping to achieve the interoperability of the involved actors and tools in collaborative project environments. The essence of the developed interoperability approach is in the consistent definition of a new IFC View for product catalogues that pulls together the needed product, cost and management data.

Select this Article		An Efficient Numerical Method in Second—Order Inelastic Analysis of Space Trusses Hamed Saffari, Nadia M. Mirzai, Iman Mansouri, and Mohammad H. Bagheripour Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000193 Posted ahead of print 12 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, the Newton—Raphson method is combined with three different algorithms. These algorithms are the Generalized Minimum Residual (GMRES), the Least Squares (LSQR) and the BiConjugate Gradient (BCG). From these algorithms, the most effective one in reducing the number of iterations and the time required is identified. A common characteristic of these algorithms is that they replace the inversion of tangent stiffness matrix with an iterative procedure to solve the linearized system of equations. A computer program based on three algorithms is developed to numerically solve a system of nonlinear equations. The procedure can be applied to analysis of structures with complex behaviors, including unloading, snap—through buckling, and inelastic post—buckling analyses. In order to demonstrate the efficiency and accuracy of the method developed here, some well—known trusses are investigated and analyzed using the various algorithms mentioned above. Results show that the BiConjugate Gradient algorithm is a more effective scheme to be coupled with the Newton—Raphson method when nonlinear structural problems are to be solved, having considerable savings in computational cost and time. Furthermore, the BCG algorithm is improved for solving system of nonlinear equations. Finally, results reveal that the improved BCG method drastically reduces the computational time and the number of iterations while the accuracy of the results is maintained.

Select this Article		Automatic Generation of 3D Building Models from Complicated Building Polygons Kenichi Sugihara and Junne Kikata Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000192 Posted ahead of print 11 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract A 3D urban model is an important information infrastructure that can be utilized in several fields, such as, urban planning and game industries. However, enormous time and effort have to be spent to create 3D urban models, using 3D modeling softwares such as 3ds Max or SketchUp. In this paper we will employ automatic generation of 3D building models through integrating GIS and CG (Computer Graphics). An integrated system is proposed for automatically creating 3D building models from building polygons (building footprints) on a digital map. Since most building polygons' edges meet at a right angle (orthogonal polygon), a complicated orthogonal building polygon can be partitioned into a set of rectangles. The integrated system partitions orthogonal building polygons into a set of rectangles and places rectangular roofs and box‐shaped building bodies on these rectangles. In order to partition an orthogonal polygon, a useful polygon expression (RL expression: edges. Right & Left turns expression) and a partitioning scheme was proposed. In our research, a new scheme for partitioning complicated orthogonal building polygons is proposed. In the digital map, however, not all building polygons are orthogonal. To place parts of a building properly, in either orthogonal or non‐orthogonal polygons, the proposed system places parts of a building, such as windows along the inner contour which is setbacked from the original building polygon by straight skeleton computation, the algorithm of which is clarified. For a multiple bounded polygon (a building polygon bounded by outer polygons), a new scheme is also presented for creating a complicated shape of building model or a ‘multilayer building’.

Select this Article		Tracking and Predicting Barge Locations on Inland Waterways Duminda I. B. Randeniya and Michael R. Hilliard Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000191 Posted ahead of print 9 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract In efforts to improve efficiency, safety and security, several groups involved in inland waterway navigation have an interest in improving tracking of barges moving on waterways. Automated tracking devices have inherent limitations, and there is a need to predict locations over the next several hours. We present a non‐linear, probabilistic prediction model developed and implemented to track spatial location and other navigation characteristics of a barge traveling on the inland waterway system. A pre‐filter, to check the validity of the measurements, a non‐linear speed estimation process, and a Kalman filter to predict the navigation solution of the barge is developed in this work. Due to the complex dynamics involved in the barge navigation system, a non‐linear stochastic model was developed in state space to represent the process and measurement processes. The algorithm was verified using actual measurements obtained from multiple barges on multiple rivers acquired from different sensors. The results show a reliable and robust prediction algorithm for tracking inland waterway barges.

Select this Article		Applying Basic Control Theory Principles to Project Control: A Case Study of Off‐Site Construction Shops Reza Azimi, SangHyun Lee, and Simaan M. AbouRizk Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000190 Posted ahead of print 17 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Off‐site construction has become increasingly popular in industrial construction projects over the past decade due to its advantages: higher productivity, better quality, better safety and improved time and cost effectiveness. The fast paced nature of off‐site construction environments and the constraints induced by the construction site, along with the existing limitations within the shop, make the control process of off‐site construction quite challenging. High quality real‐time data provided by utilizing new technologies can significantly improve and speed up the process of monitoring projects and identifying possible deviations; however, to be effective, decisions on corrective measures have to be made as quickly as possible. This paper presents an enhanced method based on the control theory concept for taking timely corrective actions to control the dynamic and fast‐paced environments of off‐site construction shops. The proposed method allows project managers to perform punctual non‐linear data analysis and predict the behavior of the performance of the shop. This leads to promptly determining the best corrective action in the case of variance to achieve a desired performance level with minimum cost. To illustrate its feasibility and potential for improving project control, the proposed approach was successfully implemented in an actual off‐site structural steel fabrication shop.

Select this Article		Damage Identification of Multi Storey Shear Structure from Sparse Modal Information S. K. Panigrahi, S. Chakraverty, and B. K. Mishra Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000189 Posted ahead of print 17 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents a procedure to identify the damage of multi storey shear structure from sparse modal information. Practically, it is difficult and expensive to measure modal response at many locations. A method has been proposed here to compute the full modal information of a particular mode simply by knowing the frequency value of that mode. Then the concept of the residual force vector along with Genetic Algorithm has been implemented to get the location and extent of damage. Frequencies at different number of modes with and without corresponding partial mode shape is used as input to the model and results are compared to find out minimum number of modal information and their locations required for the best result. Experimental data are simulated numerically by solving eigen value problem of the damaged structure with inclusion of random noise on the vibration characteristics. Reliability of the procedure has been shown by various examples of multi storey structure with different damaged situations. The model is also validated with some published results in this area to show the efficacy of the methodology.

Select this Article		Flying Voxel Method with Delaunay Triangulation Criterion for Façade/Feature Detection for Computation Linh Truong‐Hong, Debra F. Laefer, M. ASCE, Tommy Hinks, and Hamish Carr Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000188 Posted ahead of print 17 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract In an effort to reconstruct geometric models of building façades from terrestrial laser scanning data directly without either manual intervention or any third party computer‐aid design package, a new algorithm is introduced. The algorithm detects building boundaries and features and converts the point cloud data into a solid model appropriate for computational modeling. The algorithm combines a voxel‐based technique with a Delaunay triangulation based criterion. In the first phase, the algorithm detects boundary points of the façade and its features from the raw data. Subsequently, the algorithm determines whether holes are actual openings or data deficits caused by occlusions and then fills unrealistic openings. The algorithm's second phase creates a solid model using voxels in an octree representation. The algorithm was applied to the façades of three masonry buildings. For these buildings, the algorithm successfully detected all openings and reconstructed the façade boundaries correctly. Geometric validation of the models against measured drawings showed overall dimensions correct to 1.2%, most opening areas to 3%, and simulation results within 5% of those predicted by a CAD‐based model.

Select this Article		Assessment and Control of the Quality of Data Used during Dam Reviews by Using Expert Knowledge and the ELECTRE TRI Method Corinne Curt and Aurélie Talon Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000187 Posted ahead of print 17 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Generally, experts use very large quantities of data during the analysis of civil works. These data are of four main types: visual observations, monitoring data, data calculated from models and design and construction data. They are frequently “imperfect”: they contain uncertainty, imprecision, incompleteness. These imperfections have various roots, for instance, material location and sampling, number of measurement instruments, maintenance, such as scraping downstream slope, and frequency of monitoring measurement, etc. The method we propose in this paper first permits the identification of the various sources of imperfection and their definition as criteria; second, it provides a reliable way of assessing these criteria; third, it applies the multi‐criteria analysis ELECTRE TRI method to aggregate the values resulting from the assessment of the criteria. Finally, corrective actions are proposed to maintain or replace the measurement system under standard operating conditions. The method was applied to a real‐case study.

Select this Article		Pavement Layer Data Repository Using a Spatio‐Temporal Block Model Zhaohua Wang, Ph.D. and Yichang (James) Tsai, Ph.D., P.E., M. ASCE Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000186 Posted ahead of print 17 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Historical and in‐service pavement layer data along with pavement Maintenance, Rehabilitation and Reconstruction (MR&R) history is critical information for developing a reliable and accurate pavement performance model that is indispensably necessary for the support of a pavement management system. The conventional homogeneous segmentation method for pavement layer data repository has the problem of excessive segmentation, which may result in inefficient data storage and incomplete data. To address this issue, a spatio‐temporal block model is proposed to eliminate the need of homogeneous segmentation, and, thus, avoid the excessive segmentation and the creation of tiny pavement segments. Three time factors are defined for each pavement layer block to maintain the temporal information of a pavement layer structure. A depth‐first‐search (DFS) based cluster searching algorithm is used for reconstruction and visualization of pavement structures as well as for data manipulation. A case study is presented to demonstrate the application developed using the proposed model and algorithms. The computing time and merits of the proposed methodology are also discussed.

Select this Article		Error Correction Methods for Construction Site Image Processing under Changing Illumination Conditions Yuhong Wu, Changyoon Kim, and Hyoungkwan Kim Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000183 Posted ahead of print 3 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Image processing is an effective tool for automated monitoring of construction projects. For the last decade, it has gained increasing acceptance in its application to progress monitoring, productivity analyses, and quality assurance. However, there exists a notable downside in image processing, especially in outdoor applications such as construction project monitoring: image quality is heavily affected by ambient lighting conditions. Poor or undesirable lighting conditions produce sub‐standard quality images, which generally lead to a high level of errors in the related image processing for information extraction. This paper presents error correction methods that can improve the image processing results for construction progress monitoring in the post‐processing stage. The methods are applied in the post‐processing stage. The key idea behind the error correction methods is the concept of ‘priority’ to classify input images and project information into several categories based on data reliability, and intelligently use the classified information for more accurate analyses of the project progress. Tests in real construction sites showed that these post processing methods significantly increased the accuracy of image processing‐based construction progress monitoring.

Select this Article		Optimum Accuracy of Two Dimensional Strain Measurements Using Digital Image Correlation Chris Lee, W. Andy Take, and Neil A. Hoult Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000182 Posted ahead of print 3 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Foil and vibrating wire strain gages have an optimum strain measurement accuracy of 1 microstrain. However they can only provide discrete strain readings over a single fixed gage length. Digital image correlation (DIC) offers an alternative to conventional strain gauges in that a 2‐dimensional surface strain field can be obtained from a single sensor (camera). However the benefits of 2‐D strain measurements are only worthwhile if a similar level of measurement accuracy to conventional strain gages can be achieved. This paper presents the results of an investigation into the optimum strain measurement accuracy that can be achieved using the 2‐D technique on artificial images (which eliminate errors associated with cameras and lighting). The principle of the 2‐D DIC technique and its historical development will be introduced. Then three potential techniques for taking strain measurements will be presented and compared: single readings, averaged linear readings and an approach based on Mohr's circle. The Mohr's circle approach was found to be the most accurate and was not susceptible to image misalignment. Strain measurement accuracy was also found to be affected by the bias error of the subpixel interpolation scheme but the use of an 8 coefficient B‐spline was found to produce satisfactory results within the error of a conventional strain gages. Gage length was also found to have a significant impact on strain measurement accuracy indicating that measuring strains in a material where there are variations across the strain field could result in a loss of measurement accuracy. However, overall it was found that 2‐D DIC offers the same strain measurement accuracy as conventional strain gages when used under ideal conditions.

Select this Article		Multi‐Agent Approach for Real‐Time Collision Avoidance and Path Re‐Planning for Cranes Cheng Zhang and Amin Hammad Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000181 Posted ahead of print 3 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Collisions on construction sites are one of the major causes of fatal accidents. The present paper proposes a multi‐agent‐based approach to provide real‐time support to the staff of construction projects. Collision avoidance is achieved by informing the crane operators about potential collisions, and by providing motion re‐planning for crane operations. During the planning stage, a 3D model of the static environment is created, and collision‐free motion plans are generated by the agents for the cranes considering engineering constraints and operation rules. During the actual construction work, all mobile objects are tagged when entering the monitored area. A site state agent uses a Real‐Time Location System (RTLS), such as an ultra‐wideband (UWB) system to collect location data, calculates the poses of the objects on site, and sends this information to other agents. By using this real‐time updated information, agents can detect potential collisions and re‐plan the path for the cranes for collision avoidance. A coordinator agent coordinates the movement of cranes by deciding the priorities. The site state agent, coordinator agent, and crane agents can communicate and negotiate with each other to make better decisions. The framework of the multi‐agent system is described in detail and a prototype system is developed. Three case studies are used to verify and validate the proposed approach. The benefit of using the agent system is that real‐time collision avoidance can be achieved by providing more awareness of the site situation and decision‐making through communication and negotiation between multiple agents, which results in safer and more productive work environment.

Select this Article		Integrative Structural Design F. Gerold, K. Beucke, and F. Seible Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000180 Posted ahead of print 3 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Current processes for design and detailing in structural engineering are often broken up into a sequence of partial processes, due to the complexity of the problem. But sequential additions of separate solutions rarely lead to an optimal design. For example, the basic structural system is often developed with its geometry and topology, but without consideration of important aspects of structural performance, like robustness, redundancy, ductility. Decisions on performance are left for later design stages, when it is still possible to change details, but too late to improve the structural system. A design that takes into account multiple objectives, such as safety, functionality and aesthetics, requires a complete reconsideration of our conventional sequential structural design process. Most engineering tools were developed many years ago as technology was much more limited, resulting in separate tools for separate objectives to be used in succession. In this paper, a new approach is presented as Integrative Structural Design, where separate state‐of‐the‐art solutions are synchronized in such a way that designers are not confined to predetermined solution paths but rather are enabled to consider different objectives concurrently including interactions between objectives. The resulting design tool for the conceptual, interactive modelling, simulation and visualization of structural design or integrative design is presented under the term “Integrative Structural Design System” (ISDS).

Select this Article		Automated Visual Recognition of Dump Trucks in Construction Videos Ehsan Rezazadeh Azar and Brenda McCabe Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000179 Posted ahead of print 9 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract Earthmoving plants are essential but costly resources in the construction of heavy civil engineering projects. In addition to proper allocation, ongoing control of this equipment is necessary to ensure and increase the productivity of earthmoving operations. Captured videos from construction sites are potential tools to control earthmoving operations; however, the current practice of manual data extraction from surveillance videos is tedious, costly and error prone. Cutting edge computer vision techniques have the potential to automate equipment monitoring tasks. This paper presents research in the evaluation of combinations of existing object recognition and background subtraction algorithms to recognize off‐highway dump trucks in noisy video streams containing other active machines. Two detection algorithms, namely Haar‐HOG and Blob‐HOG, are presented and evaluated for their ability to recognize dump trucks in videos as measured by both effectiveness and timeliness. The results of this study can help practitioners select a suitable approach to recognize such equipment in videos for real‐time applications such as productivity measurement, performance control, and proactive work‐zone safety.

Select this Article		Multi‐Resolution Information Mining for Pavement Crack Image Analysis Y. O. Adu‐Gyamfi, N. O. Attoh Okine, Gonzalo Garateguy, Carrillo Rafael, and Gonzalo R. Arce Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000178 Posted ahead of print 29 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Empirical mode decomposition (EMD) is a multi‐resolution data analysis method recently developed to cater to the inherent nonstationarity in real world signals. A 2D extension of EMD is used in this paper as a pavement distress image analytical tool. The algorithm decomposes an image into a set of narrow band components (called Bidimensional Intrinsic Mode Function or BIMF) which uniquely reflect the variations in the image. While some components could have a good characteristic of the edges in the image, others might hold fidelity to the shape and size of objects or the trends in the image. This implies that the complete spatial and frequency characteristic of a desired image feature might also be divided into the different components. This means that all the attributes of a desired feature might not be found in a single component. An optimal solution will require image mining from the different component resolutions to accurately extract those specific attributes without compromising certain spatial and frequency characteristics. Two major contributions to pavement image analysis are achieved. First, the paper explores pavement image denoising or enhancement by combining the EMD and a weighted reconstruction technique as a tool for background standardization of images acquired under different types of illumination effects. Secondly, using Principal Component Pursuit (PCP), the authors reconstruct a composite image by selecting salient information from coarse and fine resolution BIMFs that will be useful for accurate extraction of linear patterns in a pavement distress image. Compared with conventional image reconstruction or approximation techniques, the methodology used in this paper yields better results.

Select this Article		Analysis of Three Indoor Localization Technologies for Supporting Operations and Maintenance Field Tasks Saurabh Taneja, Asli Akcamete, Burcu Akinci, James H. Garrett, Jr., Lucio Soibelman, and E. William East Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000177 Posted ahead of print 29 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Locating building components that need to be worked upon during maintenance tasks is critical to timely repair of the component and mitigation of the damage. The process of locating a component or a person in a facility is labeled as “indoor localization.” The objective of this research study is to analyze the feasibility of three indoor localization technologies for supporting operations & maintenance (O&M) field tasks, namely: 1) Wireless LAN (WLAN); 2) Radio Frequency Identification (RFID) tags; and 3) Inertial Measurement Units (IMU). These technologies have been selected based on the requirements of the localization needed for supporting O&M field activities. We have extended a previous work by Pradhan et al. (2009b), which tested RFID‐based location in an indoor environment, by testing the three selected technologies in the same test bed and using the same hypothesis and fingerprinting approach developed by Pradhan et al. (2009b). The two main motivations behind using the same test bed and same approach are to have the same baseline to evaluate the performance of three technologies and also to evaluate the performance of RFID‐based localization over longer periods. The results in the present study show that RFID‐based localization suffers from a decrease in signal strength levels over several years, WLAN‐based localization suffers from variations in signal strength and localization based on IMU suffers from drift in the sensors of IMU. It is observed that prior knowledge of the layout of a facility can improve the performance of WLAN, RFID and IMU‐based localization.

Select this Article		Data Model‐Centered Four‐Dimensional Information Management System for Road Maintenance Satoshi Kubota and Ichizou Mikami, M. ASCE Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000176 Posted ahead of print 29 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Roads are networks that connect social infrastructure and accommodate the delivery of emergency services. Because of the importance of roads, they should be safe and kept in good condition. To perform effective road management, the use of spatial and temporal information is necessary. Maintenance management is an essential operation that should be carried out effectively for maintaining, repairing, and rehabilitating roads. It is necessary to accumulate information produced during the entire life cycle of a road in order to analyze problems and find solutions within a temporal sequence and to maintain roads strategically and effectively. In this paper, four‐dimensional information is defined as the combination of three‐dimensional spatial information and temporal information. Four‐dimensional information is required for storing the historical information of road condition. This paper proposes a four‐dimensional information management system to collect, accumulate, share, and utilize four‐dimensional information. The system consists of a spatial data infrastructure, road data models, a model library, a common system interface, common functions, a road database, and a road application system. The road application system provides functions for simulation, progress management, and the representation of four‐dimensional information. The system is demonstrated using actual data on road maintenance. It is verified that the system has the capability to be applied in practice.

Select this Article		A Bee Colony Optimization Approach to Solving the Anti‐Covering Location Problem Branka Dimitrijević, Dušan Teodorović, Vladimir Simić, and Milica Šelmić Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000175 Posted ahead of print 24 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Bee Colony Optimization (BCO) is a relatively new meta‐heuristic designed to deal with hard combinatorial optimization problems. It belongs to the nature‐inspired methods that explores collective intelligence applied by the honey bees during nectar collecting process. In this paper we apply BCO to the Anti‐Covering Location Problem (ACLP), one of the fundamental problems in the area of discrete location. Having in mind that BCO algorithm has not been used in the literature related to the ACLP so far, it was challenge for us to test its performances on this NP hard problem. The performed numerical experiments on the well known benchmark problems show that the proposed algorithm can generate high‐quality solutions in reasonable CPU times.

Select this Article		Information Requirements for Design and Detailing of Reinforced Concrete Frames in Multi‐User Environments Engin Burak Anil, Gokhan Unal, and Ozgur Kurc Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000174 Posted ahead of print 3 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract The design and detailing of reinforced concrete frames is a complex process that requires intensive real‐time information exchange between various design tasks. The monolithic behavior of concrete, differences in the geometric representation of structural members during the analysis and design stages, and design code requirements throughout the process add new dimensions to the problem. Additionally, especially in large projects, reinforced concrete structures are designed and detailed by several engineers simultaneously. These complexities can be resolved and the overall quality of the design can be improved by identifying information requirements for managing the design information between the design and detailing tasks and thus between structural engineers. In this paper, requirements for managing information for multi‐user design and detailing of reinforced concrete frames are identified and a prototype information model has been implemented based on existing literature. The means of performing design computations on a standard basis and the requirements of a multi‐user design have also been integrated into the abstraction of objects in the library. Definition of high level classes that integrate multiple structural components, parametric relationship between components, and separating shear and flexural design tasks were determined as the main requirements for such a model.

Select this Article		Student Background and Implications for Design of Technology Enhanced Instruction Thuy Nguyen, Fernando Mondragon, S. M. ASCE, William J. O'Brien, M. ASCE, Kathy Jackson, Raja R. A. Issa, F. ASCE, and Eddy M. Rojas, A. M. ASCE Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000173 Posted ahead of print 3 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Knowledge of students' construction and technology background is an important input to the process of designing technology‐enhanced instruction. Current literature in student background either is not specific for the construction/civil engineering student population or lacks direct implications for pedagogical design. This paper presents a survey study that assesses students' self‐reported technology skills and attitude, learning preferences, and baseline construction knowledge. The survey is designed as a questionnaire with three sections: demographic and background information, technology attitude and exposure, and construction‐related knowledge. From the 280 data points collected, it was found that today's students are exposed to a wide range of technology applications. They had a positive attitude toward technology, were enthusiastic video game players, and strongly preferred learning activities that involved interactions, whether these interactions were face‐to‐face or mediated by technology. These findings suggest that technology‐assisted learning would excite and engage students. The paper also provides a discussion on specific pedagogical design implications of the findings and ways in which these could be incorporated in the design of technology‐enhanced learning tools.

Select this Article		Crane Pose Estimation Using UWB Real‐Time Location System C. Zhang, A. Hammad, and S. Rodriguez Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000172 Posted ahead of print 3 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Operating a crane is a complex job, which requires not only the experience of the operator, but also sufficient and appropriate real‐time support to conceive and react to the environment. To help the crane operator, crane pose estimation is necessary to predict potential collisions. Environment perception technologies are essential to update environment information. Location data of the components of the cranes should be used to calculate the pose of the crane that can be used for collision avoidance. This paper aims to investigate how to collect and efficiently process the location data in near real time using ultra wideband (UWB) technology for providing intelligent support to crane operators. First, the requirements of using UWB technology in construction sites to track crane movements are defined. Then, the details the UWB system setting method is investigated to decide the location of sensors, and the number and location of tags attached to different components of a crane. A location data processing method is proposed to improve data quality by filtering noisy data and filling in missing data in near real time. An outdoor test is presented to demonstrate the feasibility of applying the proposed approach. Location data of a crane boom are collected and processed in near real time. The results of the test show a good potential to calculate the poses of crane booms using UWB RTLS.

Select this Article		A Formalized Representation for Supporting Automated Identification of Critical Assets in Facilities during Emergencies Triggered by Failures in Building Systems Fernanda Leite and Burcu Akinci Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000171 Posted ahead of print 3 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents a formalized vulnerability representation schema that targets supporting vulnerability assessment in a facility during an emergency triggered by a failure in a building system, by identifying which critical assets might be affected by the current emergency. The representation schema captures to which threats specific content are vulnerable. Specifically, it enables the representation of threats and how they can be traced spatially. Moreover, it provides a way to describe content by its type, and its exchange and use values as a way to identify and prioritize vulnerabilities, and to represent different types of content collections. Such a representation schema is needed for supporting automated vulnerability assessment in building emergencies. The formalized representation schema was tested for coverage in synthetic tests, using OmniClass for content and the Emergency Response Guidebook for threats. For content, 84% of 245 content types in OmniClass were successfully represented using the schema. These 245 content types represent the content commonly included in facility asset management databases. For threats, 79% of threats were successfully represented using the schema. The schema was also tested for extensibility in user tests, in which 99% of content types and 83% of threats cited by users were successfully represented using the schema.

Select this Article		Target‐Focused Local Workspace Modeling for Construction Automation Applications Yong K. Cho, A. M. ASCE, Chao Wang, Pingbo Tang, A. M. ASCE, and Carl T. Haas, M. ASCE Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000166 Posted ahead of print 19 September 2011 Full Text: \| Download PDF
	+ -	Show Abstract To improve the efficiency and effectiveness of the geometric data collection and processing for automated construction operations, a light‐weight hybrid LADAR system was developed to enable semi‐automatic targeted data collection, so that an operator can quickly obtain high‐quality data for parts of the workspace critical for an on‐going operation. In order to further improve the precision of separating needed data from background and irrelevant data, using this custom‐designed system, the relationships were investigated among the amplitude of data points, the scanning distance, time‐of‐flight, and the grayscales of objects. Thus, positive control of scanning position, orientation, field of view and amplitude is enabled. For construction robotics applications in confined spaces such as power plants, that is a critical capability. The evaluation results indicate the efficiency and effectiveness of the semi‐automatic targeted scanning approach on reducing the scanning time and data size, and the effectiveness of the proposed target‐focused data collection approach.

Select this Article		3D Tracking of Construction Resources Using an On‐Site Camera System Man‐Woo Park, Christian Koch, and Ioannis Brilakis, M. ASCE Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000168 Posted ahead of print 19 September 2011 Full Text: \| Download PDF
	+ -	Show Abstract Vision trackers have been proposed as a promising alternative for tracking at large‐scale, congested construction sites. It provides the location of a large number of entities in a camera view across frames. However, vision trackers provide only 2D pixel coordinates which are not adequate for construction applications. This paper proposes and validates a method that overcomes this limitation by employing stereo cameras and converting 2D pixel coordinates to 3D metric coordinates. The proposed method consists of 4 steps — camera calibration, camera pose estimation, 2D tracking, and triangulation. Given that the method employs fixed, calibrated stereo cameras with a long baseline, appropriate algorithms are selected for each step. Once the first two steps reveal camera system parameters, the third step determines 2D pixel coordinates of entities in subsequent frames. The 2D coordinates are triangulated based on the camera system parameters to obtain 3D coordinates. The methodology presented in this paper has been implemented and tested with data collected from a construction site. The results demonstrate the suitability of this method for on‐site tracking purposes.

Select this Article		Case Study on Development of a Fuzzy Risk Ranking Model for Prioritizing Manhole Inspection D. Tran, J. Mashford, R. May, and D. Marlow Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000162 Posted ahead of print 18 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract Manholes are designed to provide access points to underground sewer networks for inspection and maintenance. Manhole collapses, while rare, can result in severe consequences and have a significant impact on the performance of the sewer. This paper presents a case study on the development of a risk ranking model using fuzzy set theory and the analytical hierarchy process for individual manholes of sewer networks. The fuzzy risk ranking model (FRM) considered both the likelihood and consequence of collapse. The performance of the FRM was validated against ten manholes with known poor condition. The results were also compared against a previously developed risk ranking scheme, with regards to consistency and repeatability of the relative ranking of assets. The results suggested that the FRM might provide better performance, though only limited data was available for validation. The process adopted in constructing the scheme is considered to be systematic and auditable.

Select this Article		Deployment Strategies and Performance Evaluation of a Virtual‐Tag‐Enabled Indoor Location Sensing Approach Nan Li, Shuai Li, Burcin Becerik‐Gerber, and Gulben Calis Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000161 Posted ahead of print 18 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract Indoor location information is valuable to the construction industry for a wide range of purposes, including on‐site personnel safety, asset security, facility maintenance, and in‐building emergency response. Indoor location sensing includes presence detection and location calculation, for which a number of technologies and algorithms have been tested. To advance the research in this area, the paper proposes an improved radio frequency identification (RFID) based location sensing algorithm that uses virtual tags to increase the cost effectiveness and robustness. A series of tests were conducted in a controlled environment, and the findings on algorithm parameter optimization, equipment deployment strategies, system accuracy/cost tradeoff, and robustness are presented in the paper. The results show that a mean accuracy of 1.94 ± 0.17 m for stationary targets and 1.42 ± 0.49 m for mobile targets can be achieved, and that the system holds promise for robustness. Virtual tags are proven to reduce the cost, and improve the system robustness.

Select this Article		Extended Period Simulation for Pressure‐Deficient Water Distribution Network K. S. Jinesh Babu and S. Mohan Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000160 Posted ahead of print 18 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract A water distribution network is said to be under pressure‐deficient condition when hydraulic‐head or pressure‐head at any of its nodes fall below the required level. The demands at these pressure‐deficient nodes cannot be fully satisfied. In order to make the analysis simple, it is generally assumed that the demand is fully satisfied irrespective of the pressure‐head available and this approach is referred as demand‐driven analysis. Due to simplicity, demand‐driven analysis received great attention in the past and several computer packages are readily available for the analysis of normal operational water distribution network. On the other hand, head‐driven or pressure‐driven analysis could be effectively used to analyze the pressure‐deficient condition as these methods consider the head‐discharge relationship at every node. This paper presents a pressure‐deficient analysis algorithm using the widely used demand‐driven analysis based solver. The proposed algorithm is validated through benchmark water distribution networks and then extended period simulation is carried out for a multiple source pumped network. The analysis shows that the proposed algorithm could find the partial nodal outflows and corresponding hydraulic‐head values in a single hydraulic simulation run.

Select this Article		Agent‐Based Modeling of Occupants’ Impact on Energy Use in Commercial Buildings Elie Azar, S. M. ASCE and Carol C. Menassa, Ph.D., A. M. ASCE Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000158 Posted ahead of print 4 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract Energy modeling is globally used during the design phase to estimate future building energy performance. Predictions obtained from common energy estimation software (e.g., eQuest, Energy Plus) typically deviate from actual energy consumption levels. This discrepancy can be mainly attributed to the misrepresentation of the role that building occupants play in the energy estimation equation. In fact, although occupants might have different and varying energy use characteristics over time, current energy estimation tools assume they are constant. This paper proposes a new Agent‐Based approach to commercial building energy modeling by accounting for the diverse and dynamic energy consumption patterns among occupants, in addition to the potential changes in their energy use behavior due to their interactions with the building environment and with each other. The impact of an active modeling of occupancy is then illustrated in a case study of an office in a university building, where more than 25 percent variation in the design energy consumption was obtained when using the proposed method versus a traditional commonly used method with static occupancy parameters.

Select this Article		A Model‐Based Groupware Solution for Distributed Real‐Time Collaborative 4D Planning via Teamwork Wei Zhou, Panagiotis Georgakis, David Heesom, and Xiandong Feng Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000153 Posted ahead of print 30 July 2011 Full Text: \| Download PDF
	+ -	Show Abstract Construction planning plays a fundamental role in construction project management that requires team working among planners from a diverse range of disciplines and in geographically dispersed working situations. Model‐based four‐dimensional (4D) computer‐aided design (CAD) groupware, though considered a possible approach to supporting collaborative planning, is still short of effective collaborative mechanisms for teamwork due to methodological, technological and social challenges. Targeting this problem, this paper proposes a model‐based groupware solution to enable a group of multidisciplinary planners to perform real‐time collaborative 4D planning across the Internet. In the light of the interactive definition method, and its computer‐supported collaborative work (CSCW) design analysis, the paper discusses the realization of interactive collaborative mechanisms from software architecture, application mode, and data exchange protocol. These mechanisms have been integrated into a groupware solution, which was validated by a planning team in a truly geographically dispersed condition. Analysis of the validation results revealed that the proposed solution is feasible for real‐time collaborative 4D planning to gain a robust construction plan through collaborative teamwork. The realization of this solution triggers further considerations about its enhancement for wider groupware applications.

Select this Article		A Planning Based Approach for Fusing Data from Multiple Sources for Construction Productivity Monitoring Anu Pradhan and Burcu Akinci Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000155 Posted ahead of print 30 July 2011 Full Text: \| Download PDF
	+ -	Show Abstract Project management tasks, such as productivity monitoring and cost estimation, require data to be fused from multiple data sources. Data fusion approaches incorporated in the existing research studies within construction management domain support a specific task or a decision (e.g., labor productivity monitoring or defect detection). Hence, most of the previously developed approaches do not necessarily support tasks other than the ones that they were intended for. This paper describes an automated planning approach as a general way to fuse data from multiple sources to support construction productivity monitoring task. A prototype system, which incorporates two planning algorithms, was developed to validate the generality of the approach based on representative queries of construction engineers and managers, identified in previous research studies.

Select this Article		Generalized Eigenvalue Analysis of Symmetric Prestressed Structures Using Group Theory Yao Chen and Jian Feng, Ph.D. Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000151 Posted ahead of print 20 July 2011 Full Text: \| Download PDF
	+ -	Show Abstract As conventional approaches for calculating natural frequencies do not make full use of the inherent symmetry of a structure, the rising degree of freedoms often leads to significant increase in computational demand. In this study, a simplified technique for analyzing dynamic characteristics of symmetric prestressed structures is described using group theory. Firstly, the generalized eigenvalue equation of a prestressed structure based on tangent stiffness matrix and lumped mass matrix is built to get natural frequencies and the corresponding vibration shapes, where the contribution of initial prestresses is considered. A symmetry‐adapted coordinate system for the structure is adopted to block‐diagonalize the stiffness and mass matrices. The complexity of generalized eigenvalue equation is reduced by solving the mutually independent subspaces, and thus natural frequencies and the corresponding vibration modes could be obtained. Illustrative examples point out the general procedure, and show the superiority. Compared with numerical results, it has been proven that the novel symmetry method using group theory is accurate and very efficient.

Select this Article		Optimal Removal of Heavy Metals Pollutants from Groundwater Using a Real Genetic Algorithm and Finite Difference Method A. R. Awad, I. Von Poser, and M. T. Aboul‐Ela Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000147 Posted ahead of print 2 July 2011 Full Text: \| Download PDF
	+ -	Show Abstract The purpose of this research is to investigate the capability of the real genetic algorithm to remove the heavy metals pollutant plume from an aquifer. The real genetic algorithm has been used in conjunction with proven and accepted finite difference analysis to reach an efficient solution. It also illustrates the interaction between the real GA optimizer and the finite difference technique. Two scenarios regarding the wells positions, number of wells, rate of pumping at each well and total cost were determined for the purpose. A new system has been developed for removing heavy metals (Mercury Hg and Cadmium Cd ) from groundwater in a real problem, and proved to be optimal. Real‐coding genetic algorithms (GAs) proved to be a practical means of optimizing engineering solutions to problems related to groundwater quality management, in particular those involving discontinuous functions. The real GA can be used with accredited finite difference method towards an optimal solution. The developed application of a combined simulation‐optimization method for clean‐up of contamination from a real landfill in a coastal area of Syria can also be used in other water resources quality applications.

Select this Article		Modeling of User Design Preferences in Multi‐Objective Optimization of Roof Trusses Breanna Bailey and Anne M. Raich Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000145 Posted ahead of print 27 June 2011 Full Text: \| Download PDF
	+ -	Show Abstract Many conceptual design programs determine optimality by relying on quantifiable design objectives such as minimizing weight and deflection. Qualitative design criteria related to architectural or constructability requirements, however, are not typically considered. This paper presents a novel preference‐prediction model that evaluates user preference as an explicit design objective in the topology and geometry optimization of roof trusses. During optimization each truss design is characterized using a set of nine, quantifiable features. A trained neural network inputs the characteristic truss feature values for each proposed design and outputs an integer value that indicates the user's preference for that design. To reduce the number of user interactions required to collect the required neural network training data, a Kohonen self‐organizing map clusters designs into groups based on feature similarities. Clustering allows users to indicate preferences for groups of similar trusses instead of for individual trusses. A rough‐set reduct technique removes outliers from the user‐preferred truss groups before the feature information and user preference assignments are used to train the predictive back‐propagation neural network. The preference‐prediction model is implemented in an existing multi‐objective optimization program to determine the benefits of including satisfaction of user preferences as a design objective. Trial results indicate that more Pareto‐optimal designs are identified, which increases the extent of the front, when user preferences are stated. Also, the Pareto‐optimal set includes designs that have features reflecting the imposed user preferences and features that are structurally‐optimal.

Select this Article		Improving Parallel Substructuring Efficiency by Using a Multi‐Level Approach Yuan‐Sen Yang, Shang‐Hsieh Hsieh, and Tung‐Ju Hsieh Journal of Computing in Civil Engineering doi:http://dx.doi.org/10.1061/(ASCE)CP.1943-5487.0000142 Posted ahead of print 15 June 2011 Full Text: \| Download PDF
	+ -	Show Abstract This research adopted a multi‐level substructuring approach to improve the efficiency of parallel substructure finite element analysis. The multi‐level approach employed in this work provides a simple way to parallelize the computational workload of solving the interface equation system and reduces the total time cost. Eight numerical examples of structural analysis were used to demonstrate the effectiveness of the multi‐level parallel substructural method for nonlinear dynamic structural analysis. The scalability with respect to number of cores and the problem sizes was investigated. The results showed that compared to the ordinary single‐level approach, the multi‐level approach reduces up to 50% of the interface equation system solving time, and improves the overall efficiency of parallel substructural method by up to 40% in the examples.