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Designing for 3D concrete printing presents unique challenges, particularly in vault manufacturing. There is also a lack of design support tools that consider structural performance during printing. This paper proposes a design workflow that includes form and toolpath generation, structural simulation, and optimization. The workflow is implemented on an integrated platform that includes gradient-free constrained optimization. Several objective functions were tested, and results show that the objective function that combines toolpath length and a buildability indicator performs the best. Results also show that fabrication strategy and scale significantly impact vault design, with strategies leading to longer printing times per layer showing notable reductions in overhang angle, volume, and toolpath length. A comparative study between different types of vaults indicated that cloister and squinch vaults displayed the lowest stresses and required the least amount of material. The platform was validated by printing a 1.2 m × 1.2 m cross-vault without formwork. [Display omitted] • A form and toolpath optimization workflow is proposed for the design of 3DCP vaults. • A set of design constraints are outlined for early age design of 3DCP structures. • Gradient-free constrained optimization is a valid method to optimize forms for 3DCP. • Vault design for 3DCP is largely impacted by fabrication strategy and scale. • The Workflow was validated by designing several vaults and fabricating a cross-vault. [ABSTRACT FROM AUTHOR]

Building emergencies, especially structure fires, are threats to the safety of both building occupants and first responders. It is difficult and dangerous for first responders to perform search and rescue in an unfamiliar environment, sometimes leading to secondary casualties. One way to reduce such hazards is to provide first responders with timely access to accurate location information. To address this challenge, the authors have developed a radio frequency based indoor localization framework, for which novel algorithms were designed for two different situations: one where an existing sensing infrastructure exists in buildings and one where an ad-hoc sensing infrastructure must be deployed. This paper presents a comparative assessment of this framework under different situations and emergency scenarios, and between simulations and field tests. The paper first presents an assessment of the framework in field tests, showing that it achieves room-level accuracies above 82.8% and 84.6% and coordinate-level accuracies above 2.29 m and 2.07 m, under the two situations, respectively. Moreover, the framework demonstrates considerable robustness in the tests, retaining a room-level accuracy of 70% or higher when the majority of sensing infrastructure is damaged. This paper then synthesizes results from both simulations and field tests, and demonstrates how the framework can be adapted to different situations and scenarios while consistently yielding satisfactory localization performance. [ABSTRACT FROM AUTHOR]

There is a growing need for tools automating the processing of as-built 3D laser scanned data, and more particularly the comparison of this as-built data with planned works. This paper particularly considers the case of tracking MEP components with circular cross-sections, which essentially include pipes, and some conduits and ducts. Discrepancies between the as-built and as-planned status of pipes, conduit and ductwork result from changes that occur in the field and that are either unnoticed (human error) or not reflected in the 3D model. Previous research has shown that the Hough transform, with judiciously applied domain constraints, is a practical and cost-effective approach to find, recognize and reconstruct cylindrical MEP works within point clouds automatically. Previous research has also shown that “Scan-vs-BIM” systems that are based on the geometric alignment and comparison of as-built laser scans with as-designed BIM models can effectively recognize and identify MEP components as long as they are constructed near their as-planned locations. The research presented in this paper combines the two techniques in a unified approach for more robust automated comparison of as-built and as-planned cylindrical MEP works, thereby providing the basis for automated earned value tracking, automated percent-built-as-planned measures, and assistance for the delivery of as-built BIM models from as-designed ones. The proposed approach and its improved performance are validated using data acquired from an actual construction site. The results are very encouraging and demonstrate the added value of the proposed integrated approach over the rather simpler Scan-vs-BIM system. The two main areas of improved performance are: (1) the enabled recognition and identification of objects that are not built at their as-planned locations; and (2) the consideration for pipe completeness in the pipe recognition and identification metric. [ABSTRACT FROM AUTHOR]

Abstract: In a dynamically changing environment, the manager of a maintenance and remodeling (M/R) program is confronted with an increasing complexity of coordinating and cooperating multi-resource constrained multiple projects. Uncertainty and interdependence are sources of the complexity, and cause an internal disruption of an activity and chain reactions of disturbance propagation that deteriorate the stability and manageability of the program. This paper evaluates previous endeavors to apply production control and management techniques to the construction industry, and investigates the possibility of applying other production concepts and theories to organizational program management. In particular, this paper proposes a buffer allocation strategy by which periodic buffers are allocated in the flows of program constraint resources (PCRs) to stabilize a master construction schedule instead of protecting individual activities. Comparative experiments by Monte Carlo simulations illustrate better performance of the proposed strategy in terms of program goals: productivity, flexibility, and long-term stability. [Copyright &y& Elsevier]

Abstract: Since the Internet has become widely available for construction product information (CPI) acquisition, Internet search engines and Internet based CPI providers have rapidly replaced traditional methods such as product catalogs, product manufacturer''s distributors, professional magazines, and word of mouth. This paper provides useful knowledge about this emerging Internet-based business of CPI for the stakeholders in the A/E/C industry. This paper investigates the business from three different perspectives; a) the effectiveness of current CPI providers'' websites, b) business operation models of this new industry sector, and c) critical factors for the successful operation of the Internet based CPI business using multiple surveys in the U.S. and South Korea. Lessons learned from the multi-layered assessment in this study has been actively applied and incorporated into a new web-based construction production information system which is currently developed through government support in South Korea. This study shows that reliable assessments of existing and rapidly growing CPI businesses in developed countries such as the U.S. and England can provide effective guidelines and strategies for successfully implementing this emerging market into different environments of developing countries. [Copyright &y& Elsevier]

Abstract: This paper presents a comparative study on the applications of general regression neural network (GRNN) models and conventional Box–Jenkins time series models to predict the maintenance cost of construction equipment. The comparison is based on the generic time series analysis assumption that time-sequenced observations have serial correlations within the time series and cross correlations with the explanatory time series. Both GRNN and Box–Jenkins time series models can describe the behavior and predict the maintenance costs of different equipment categories and fleets with an acceptable level of accuracy. Forecasting with multivariate GRNN models was improved significantly after incorporating parallel fuel consumption data as an explanatory time series. An accurate forecasting of equipment maintenance cost into the future can facilitate decision support tasks such as equipment budget and resource planning, equipment replacement, and determining the internal rate of charge on equipment use. [Copyright &y& Elsevier]

Abstract: Recent tighter legislation and control over issues like sustainability and disability discrimination have resulted in the need for more frequent modifications to building regulations. The challenge for building control websites is to make up-to-date building information more accessible, and to reflect the increasing complexity of the regulations. This paper reports on the content, design and functionality of a portal for the building control sector, primarily developed to aid various stakeholders in determining how relevant building regulations affect their project. The validation of the prototype involved a comparative study of two groups of forty participants to determine their evaluation of the effectiveness of the proposed portal in comparison to an existing building control website. The validation was followed by a focus group that examined the potential and limitations of the proposed approach. The findings confirmed that the portal had a positive effect on users'' abilities to achieve compliance with building regulations. [Copyright &y& Elsevier]

Abstract: Opportunities of storing energy recovered from an electro-hydraulic forklift truck are studied. The lifting system is controlled directly with an electric servo motor drive and a hydraulic pump capable of operating also as a hydraulic motor during potential energy recovery. The paper describes some of the energy storage devices available, and the analysis results for the proposed systems are compared from the energy efficiency point of view. [Copyright &y& Elsevier]

Abstract: Digital image processing methods have been actively studied and applied to various infrastructure components including bridge painting assessment. Despite the advantages of image recognition techniques to bridge coating, the results can be greatly affected by the non-uniform illumination of target conditions. It is necessary to first convert all images to a standardized background illumination condition. The effect caused from non-uniform illumination can be minimized by setting lighting conditions properly or capturing additional calibration images. However, capturing additional calibration images is not possible in many practical situations and hence a good method of shading correction is required. This paper addresses the way to correct digital bridge coating images containing non-uniform illumination, which becomes more difficult when it comes to assessing facility surfaces with rust defects. In order to choose the most appropriate one, four representative shading correction methods were selected and tested to identify their suitability to processing bridge coating images. These methods include: (1) image smoothing, (2) homomorphic filtering, (3) morphological filtering, and (4) entropy minimization method. Test results on bridge coating images showed that the entropy minimization method outperformed the other three methods. [Copyright &y& Elsevier]

Abstract: This paper describes a multiple criteria assessment experiment using the Analytic Network Process (ANP) and the Super Decisions software. The assessment experiment was based on a case study of an underground construction project in the city of Osnabruck, Germany. The project involved construction of a new 700m long sewer in the city centre. Three alternative underground construction technologies (open cut, conventional tunnelling, and microtunnelling) were evaluated using a set of multi disciplinary criteria that reflect impacts of the project on the urban environment. Results of the assessment experiment suggest that the ANP can be successfully used for assessing the environmental impact of underground construction technologies. Multiple criteria decision analysis, and the ANP in this particular assessment experiment, is relevant for evaluating construction technologies because of (1) the similar technological and economic performance of the alternative technologies; (2) the need to consider a large number of criteria reflecting the urban environment; (3) the possibility of needing to deal with incomplete data; and (4) the need for clear presentation of the results in a numerical form. [Copyright &y& Elsevier]

Abstract: Vision tracking has significant potential for tracking resources on large scale, congested construction sites, where a small number of cameras strategically placed around the site could replace hundreds of tracking tags. The correlation of vision tracking 2D positions from multiple views can provide the 3D position. However, there are many 2D vision trackers available in the literature, and little information is available on which one is most effective for construction applications. In this paper, a comparative study of various vision tracker categories is carried out, to identify which one is most effective in tracking construction resources. Testing parameters for evaluating categories of trackers are identified, and benefits and limitations of each category are presented. The most promising trackers are tested using a database of construction operations videos. The results indicate the effectiveness of each tracker in relation to each parameter of the test, and the most suitable tracker needed to research effective 3D vision trackers of construction resources. [Copyright &y& Elsevier]

Abstract: The importance of collaboration between different design disciplines has been widely recognised by the building industry. Traditionally this is achieved through physical meetings between the representatives of different design groups. However, this is facing more challenges when dealing with large and complex design problems. Various approaches have been introduced to tackle this problem, such as multi-agent systems (MAS) and the multi-disciplinary design optimisation (MDO) approaches. The former represents an advanced, ICT-based framework which facilitates collaborative design through communication, data and knowledge sharing and negotiation while the latter represents a theoretical modelling approach which facilitates collaborative design through a thorough analysis of the technical problems. By comparing the strengths and weaknesses of these approaches in facilitating collaborative design, this paper provides a roadmap study for the development of collaborative building design. [Copyright &y& Elsevier]

Abstract: In project development it is hardly possible to get exhaustive and accurate information. As a result, the situations occur, the consequences of which can be very damaging to the project. Inaccurate evaluation of the strategy related to capital investment and project implementation is one of the reasons why such estimates are not required in practice. Instead, classification approaches may be used for this purpose. Contractors of international construction projects are often faced with complicated situations working in the conditions of uncertainty in construction. One of the potential risk factors is associated with the requirements of contract conditions. One of the major aspects is project or contract management. Project developers need various models of large and complex projects'' management. The suggested method for evaluating contract effectiveness may be successfully applied at one of the stages of project management. This paper presents methods of multiattribute comparative analysis (CLARA and UniComBOS methods) of variants of classified investment risks and contract alternatives in investment and building projects of construction. A practical case illustrating the work of the methods is presented. [Copyright &y& Elsevier]

This paper presents the results of a comparative study where two decision support tools in project control have been selected: the S-Curve and Activity Gazer. The objective of the research is to characterize the impact of the visual decision-support tool in project control on the project planner's decision. Using eye tracking, a within-subject experiment was conducted with 17 participants where they were asked to make a diagnostic on a project portfolio. Results show that, despite the fact that a representation using the S-Curve helps reduce the time of diagnostics, both tools seem to have the same effect on the quality of the diagnostic by the participant. Also, we find that a representation where Activity Gazer is present is less mentally demanding than a representation where the S-Curve is present. These results suggest that the S-Curve could be improved to reduce the mental charge needed to analyze it and that new visualization tools could help project planners in their daily work. • Comparison between two visual decision support tools: S-Curve and Activity Gazer • Utilization of eye tracking • S-Curve enables a faster decision. • Activity Gazer reduces the perceived frustration of the project planner. • Project where Activity Gazer is not used seems to augment the induced cognitive load. [ABSTRACT FROM AUTHOR]