Coordinated rescheduling of precast production

Ph.DDOCTOR OF PHILOSOPH

Optimal Transportation Fleet Scheduling in Panelized Construction

Optimal transportation scheduling is crucial to improve the performance of the panelized construction supply chain. Previous studies lack transportation scheduling approaches for distribution and reverse logistics in panelized construction as a bridge to balance factory and site operations. To address the current gaps, this research proposes a genetic algorithm-based optimization framework to generate optimal distribution and reverse transportation schedules and on-site unloading schedules, considering a diverse transportation fleet (trucks and trailers), multiple sites, multiple panel types, on-site parking limitations, and assembly sequence while ensuring continuity of factory production and on-site operations. The proposed model extends and improves the existing transportation models by considering the distribution and reverse transportation operations and introducing design constraints in the transportation practices of the panelized construction. Results demonstrated that the method achieves transportation fleet efficiency of 98.8% and ensures seamless on-site operations, offering an invaluable planning tool for project managers and enhancing resource allocation for factory and construction sites

Technology and Management for Sustainable Buildings and Infrastructures

A total of 30 articles have been published in this special issue, and it consists of 27 research papers, 2 technical notes, and 1 review paper. A total of 104 authors from 9 countries including Korea, Spain, Taiwan, USA, Finland, China, Slovenia, the Netherlands, and Germany participated in writing and submitting very excellent papers that were finally published after the review process had been conducted according to very strict standards. Among the published papers, 13 papers directly addressed words such as sustainable, life cycle assessment (LCA) and CO2, and 17 papers indirectly dealt with energy and CO2 reduction effects. Among the published papers, there are 6 papers dealing with construction technology, but a majority, 24 papers deal with management techniques. The authors of the published papers used various analysis techniques to obtain the suggested solutions for each topic. Listed by key techniques, various techniques such as Analytic Hierarchy Process (AHP), the Taguchi method, machine learning including Artificial Neural Networks (ANNs), Life Cycle Assessment (LCA), regression analysis, Strength–Weakness–Opportunity–Threat (SWOT), system dynamics, simulation and modeling, Building Information Model (BIM) with schedule, and graph and data analysis after experiments and observations are identified

Simulation and optimization model for the construction of electrical substations

One of the most complex construction projects is electrical substations. An electrical substation is an auxiliary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers. Construction of electrical substation includes civil works and electromechanical works. The scope of civil works includes construction of several buildings/components divided into parallel and overlapped working phases that require variety of resources and are generally quite costly and consume a considerable amount of time. Therefore, construction of substations faces complicated time-cost-resource optimization problems. On another hand, the construction industry is turning out to be progressively competitive throughout the years, whereby the need to persistently discover approaches to enhance construction performance. To address the previously stated afflictions, this dissertation makes the underlying strides and introduces a simulation and optimization model for the execution processes of civil works for an electrical substation based on database excel file for input data entry. The input data include bill of quantities, maximum available resources, production rates, unit cost of resources and indirect cost. The model is built on Anylogic software using discrete event simulation method. The model is divided into three zones working in parallel to each other. Each zone includes a group of buildings related to the same construction area. Each zone-model describes the execution process schedule for each building in the zone, the time consumed, percentage of utilization of equipment and manpower crews, amount of materials consumed and total direct and indirect cost. The model is then optimized to mainly minimize the project duration using parameter variation experiment and genetic algorithm java code implemented using Anylogic platform. The model used allocated resource parameters as decision variables and available resources as constraints. The model is verified on real case studies in Egypt and sensitivity analysis studies are incorporated. The model is also validated using a real case study and proves its efficiency by attaining a reduction in model time units between simulation and optimization experiments of 10.25% and reduction in total cost of 4.7%. Also, by comparing the optimization results by the actual data of the case study, the model attains a reduction in time and cost by 13.6% and 6.3% respectively. An analysis to determine the effect of each resource on reduction in cost is also presented

Construction management abstracts : cumulative abstracts and indexes of journals in construction management, 1983-2000

The purpose of this document is to provide a single source of reference for every paper published in the journals directly related to research in Construction Management. It is indexed by author and keyword and contains the titles, authors, abstracts and keywords of every article from the following journals: • Building Research and Information (BRI) • Construction Management and Economics (CME) • Engineering, Construction and Architectural Management (ECAM) • Journal of Construction Procurement (JCP) • Journal of Construction Research (JCR) • Journal of Financial Management in Property and Construction (JFM) • RICS Research Papers (RICS) The index entries give short forms of the bibliographical citations, rather than page numbers, to enable annual updates to the abstracts. Each annual update will carry cumulative indexes, so that only one index needs to be consulted

Theoretical and Computational Research in Various Scheduling Models

Nine manuscripts were published in this Special Issue on “Theoretical and Computational Research in Various Scheduling Models, 2021” of the MDPI Mathematics journal, covering a wide range of topics connected to the theory and applications of various scheduling models and their extensions/generalizations. These topics include a road network maintenance project, cost reduction of the subcontracted resources, a variant of the relocation problem, a network of activities with generally distributed durations through a Markov chain, idea on how to improve the return loading rate problem by integrating the sub-tour reversal approach with the method of the theory of constraints, an extended solution method for optimizing the bi-objective no-idle permutation flowshop scheduling problem, the burn-in (B/I) procedure, the Pareto-scheduling problem with two competing agents, and three preemptive Pareto-scheduling problems with two competing agents, among others. We hope that the book will be of interest to those working in the area of various scheduling problems and provide a bridge to facilitate the interaction between researchers and practitioners in scheduling questions. Although discrete mathematics is a common method to solve scheduling problems, the further development of this method is limited due to the lack of general principles, which poses a major challenge in this research field

Evolutionary algorithms for multi-objective flexible job shop cell scheduling

The multi-objective flexible job shop scheduling in a cellular manufacturing environment is a challenging real-world problem. This recently introduced scheduling problem variant considers exceptional parts, intercellular moves, intercellular transportation times, sequence-dependent family setup times, and recirculation requiring minimization of makespan and total tardiness, simultaneously. A previous study shows that the exact solver based on mixed-integer nonlinear programming model fails to find an optimal solution to each of the ‘medium’ to ‘large’ size instances considering even the simplified version of the problem. In this study, we present evolutionary algorithms for solving that bi-objective problem and apply genetic and memetic algorithms that use three different scalarization methods, including weighted sum, conic, and tchebycheff. The performance of all evolutionary algorithms with various configurations is investigated across forty-three benchmark instances from ‘small’ to ‘large’ size including a large real-world problem instance. The experimental results show that the transgenerational memetic algorithm using weighted sum outperforms the rest producing the best-known results for almost all bi-objective flexible job shop cell scheduling instances, in overall

Application of the Lean Philosophy to reduce Carbon Emissions in the Precast Concrete Industry of Singapore

Ph.DDOCTOR OF PHILOSOPH

The effect of offsite construction on occupational health and safety

The continuous desire to improve health and safety in UK construction has in recent years been challenged to adopt offsite strategies in order to address the poor health and safety record of construction. Despite the benefits of using offsite there has been little research on the actual benefits and disadvantages of the effect of offsite on occupational health and safety. This is important given that the UK government has promoted the use of offsite to improve health and safety performance. This thesis provides a strategy for the management of offsite risk and a risk management tool has been developed. The study investigated offsite manufacturers views on offsite activities and risks in comparison with insitu activities and risks. This was achieved through three phases: phase I comprised two expert group interviews, phase II involved ergonomic audits and phase III consisted of three semi-structured interviews with three offsite manufacturers. The thesis identified that there are significant health and safety benefits of offsite. The benefits relate to specific activities within the offsite categories and context studied. Examples include the elimination of work at height, reduction in noise, reduction in work in confined space, reduction in congested work with trade overlap and greater control over work in the factory. The research revealed that there are still potential health and safety risks with offsite. Examples include; transportation and delivery of units of large size and weight with associated high consequence craneage and handling risks (unit fall and hand injury), whole body vibration, cuts, MSDs, RSIs, fumes and slips trips and falls. There appears to be little in the literature to support the identification of offsite risk issues. The study identified strategies to eliminate and reduce offsite residual risks. The case study investigated solutions to further reduce residual risks, which were further explored in phase III the semi-structured interviews. The solutions are grouped into four approaches: process change, workplace environment designing out risks, automation and the use of tools. An offsite risk management tool was developed which transfers knowledge from the study to provide awareness and management of offsite risk. The thesis provides a contribution to knowledge by providing a better understanding of offsite risks, offsite residual risks and strategies used to reduce residual risks