Schedule-dependent evolution of site layout planning

The appropriate layout of temporary facilities on a construction site has a large impact on construction safety and productivity. For the duration of a project the site layout may need to be efficiently re-organized at various intervals to satisfy the schedule requirements and to maintain site efficiency. This paper presents a practical model for schedule-dependent site layout planning in construction. The proposed model uses a combination of artificial intelligence tools (knowledge-based systems, fuzzy logic, and genetic algorithms) to generate, optimize, and re-organize the site layout plan at frequent intervals during the project. The model incorporates flexible representation of irregular site shapes and several options for placing facilities. Based on the proposed model, an automated system is developed, fully integrated with widely used scheduling software. At each schedule interval, the system recalculates the space requirements and, for the convenience of congested sites, can utilize parts of the constructed space to accommodate temporary facilities. Details of the schedule-dependent model are described, and its application in an actual case study project is presented to demonstrate its capabilities.     

Automated multi-objective optimization system for airport site layouts

Airport construction planners often face the problem of identifying optimal locations for temporary construction facilities on site, as the planned locations of these facilities usually influence important and conflicting planning objectives such as improving the efficiency of construction operations and maintaining safety on site. Careful evaluation of all feasible locations for temporary facilities and the selection of an optimal layout are needed in order to achieve these multiple important objectives. This paper presents the development of a practical automated system to optimize multiple conflicting planning objectives and provide all possible optimal tradeoff solutions among these objectives. The system is implemented and integrated in four main modules: (1) a comprehensive multi-objective optimization engine that integrates and optimizes construction work zone safety, construction-related aviation safety, construction-related airport security, and all relevant site layout costs; (2) a relational database that integrates planning data and stores all the generated optimal solutions; (3) an Input/Output module to facilitate specifying planning and optimization parameters and retrieving the generated optimal site layout solutions; and (4) a visualization module that communicates with external CAD software in order to support the visualization of the generated optimal site layout plans.     

建筑施工现场的4D可视化管理

应用4D-CAD技术,结合当前施工现场管理的实际需求,研究开发4D建筑施工现场管理系统4D-CSMS。该系统将施工场地及设施的3D模型与施工进度计划相链接,动态模拟施工过程和场地状况,实现了3D施工场地布置和施工设施的动态管理,为提高建筑工地的管理水平和工作效率,提供了科学、有效的管理方法和手段。     

The application of the ant colony optimization algorithm to the construction site layout planning problem

A good site layout is vital to ensure the safety of the working environment, and for effective and efficient operations. Moreover, it minimizes travel distance, decreases materials handling, and avoids the obstruction of materials and plant movement. Based on studies in the manufacturing industry, the cost of materials handling could be reduced by 20–60% if an appropriate facility layout is adopted. In designing a site layout, a planner will first position the key facilities that influence the method and sequence of construction, and then assign the remaining facilities in the available space that is left over. This process is similar to the positioning of facilities in the ant colony optimization (ACO) algorithm. The general principle of the ACO algorithm is to assign facilities to a location one by one, and the occupied locations are deleted from the location scope in the next assignment. In the study, ACO algorithm is employed to resolve the construction site layout planning problem in a hypothetical medium‐sized construction project. By applying fuzzy reasoning and the entropy technique, the study calculates the closeness relationship between facilities, in which the optimal site layout is affected by the mutual interaction of facilities.     

Optimisation of site layout planning for multiple construction stages with safety considerations and requirements

This paper develops a mathematical formulation to model and optimise site facility locations inside a construction site for a construction project's different stages. The existence and dimensions of a construction project's available locations and site facilities can be varied across the construction stages. Without proper planning, unnecessary facility relocations may be required in each construction stage, resulting in a higher construction cost and longer construction time due to the need to dismantle and set up site facilities. Site layout plans should be optimised using a multiple-stage model to avoid unnecessary changes to facility settings across construction stages, improving efficiency. The proposed site layout problem with multiple construction stages is formulated as a binary-mixed-integer-linear programme, which can be solved by a standard branch-and-bound algorithm using the commercial software package LINGO. The mathematical objective function established in the solution process aims to minimise the total cost, which consists of the material transportation cost between the relevant site facilities and the dismantling, setup and relocation costs for all of the involved site facilities in each construction stage. Numerical examples using the proposed mathematical model to optimise different site layout settings for a construction site are given, including (1) a reference site layout plan using the conventional static single-stage approach, (2) a multiple-stage construction site layout plan and (3) a multiple-stage site layout plan with additional safety design considerations.     

A hybrid CAD-based construction site layout planning system using genetic algorithms

The efficient layout planning of a construction site is a fundamental task to any project undertaking. In an attempt to enhance the general practice of layout planning of construction sites, the paper introduces a novel approach for producing the sought layouts. This approach integrates the highly sophisticated graphical capabilities of computer-aided design (CAD) platforms with the robust search and optimization capabilities of genetic algorithms (GAs). In this context, GAs are utilized from within the CAD environment to optimize the location of temporary facilities on site. The functional interaction between GAs and CAD and the details of the GA-based layout optimization procedure are presented. A fully automated computer system is further developed to demonstrate the practicality of the chosen approach. In order to evaluate the system's performance, a local construction project with a 24,000m² site is used. The automated system produced highly satisfactory results and showed notable flexibility through its CAD-based input/output media.     

A hybrid simulation approach for quantitatively analyzing the impact of facility size on construction projects

Sizing temporary facilities is a crucial task in construction site layout planning due to its significant impact on project productivity and cost. This paper describes a simulation-based approach for modeling the size of facilities that temporarily contain materials in construction projects. Different methods have been introduced for estimating the required size of this kind of facility; however, space limitations, particularly on congested sites, may not allow the planner to allocate the estimated space to the facilities. This study aims at quantitatively analyzing the impact of facility size on the project and modeling the managerial corrective actions to remedy the space shortage in facilities. To this end, a hybrid discrete-continuous simulation technique is adopted. Simulation is superior in modeling dynamic interactions between variables as well as modeling construction processes with inherent uncertainties. The combination of discrete and continuous simulation is used to enhance accuracy and model the project at both operational level (i.e., activity level with higher level of detail) to estimate production rate, and strategic level (i.e., macro level with lower level of detail) to account for some construction planning decisions such as material management variables. The novelty of this study is analyzing the impact of facility size on the project time and cost, while managerial actions taken to resolve space shortages are modeled, and interdependent influencing parameters of the different disciplines, such as site layout, material management, logistics, and construction process planning are integrated in a unified model. The applicability and suitability of the proposed approach is demonstrated in layout planning of a tunneling project site.     

Layout optimization of construction site facilities with dynamic freeform geometric representations

Traditional approaches to the construction site layout problem have been focused mainly on rectilinear and simple interpolated static geometrical shapes for modeling site facilities. Moreover, they have used proximity measures based on Cartesian distances between the centroids of the facilities. This is a fair abstraction of the problem; however it ignores the fact that many facilities on the construction sites assume non-rectilinear shapes that allow for better compaction within congested sites. The main focus of this research is to develop a new approach of modeling site facilities to overcome limitations and inefficiencies of previous models and to ensure a more realistic approach to construction site layout problems. A site layout optimization model was developed through a series of new algorithms for modeling regular and irregular freeform shapes of site facilities. The model mimics the “dynamic” behavior of the geometries of site facilities; where the geometrical shapes automatically modify their forms to fit in congested areas. Moreover, new proximity measures and distance measurement techniques were introduced. Furthermore, the research introduced the concept of selective zoning that significantly enhances optimization efficiency by minimizing the number of solutions through selection of pre-determined movement zones on site. At the end, a real site layout planning problem was solved using the developed model and the results were compared to two past models from the literature. The model has shown to be superior to the past models in optimizing congested and geometrically-complex site layouts.     

Mathematical programming models for construction site layout problems

We address the construction site layout problem that determines the locations of temporary facilities. Mathematical programming models for the site layout problem are proposed, which can be solved by state-of-the-art solvers to optimality. A number of safety, health and environmental concerns, such as falling objects, dusts, and noise, are incorporated in the extensions of the mathematical models. We demonstrate, using numerical experiments, the superiority of our proposed mathematical programming model over existing heuristics in terms of solution optimality and the wide applicability in terms of handling practical considerations. Based on the results of conducted experiments, the proposed method achieved a 3–19% improvement on optimality over those of the existing heuristics methods. The contribution of this research work includes the advanced development of a mathematical programming model incorporating extended concerns and solving site layout problems within reasonable time.     

Process selection for sanitation systems and wastewater treatment in refugee camps during disaster-relief situations

Disasters and emergency situations can disrupt the provision of clean water and hygienic sanitation, which are crucial for maintaining public health. Excreta disposal in emergencies has often been a low priority and this has led to the provision of unsuitable on‐site sanitation systems in urban areas. A decision algorithm for the selection of adequate excreta‐disposal solutions suitable for different disaster‐relief scenarios is presented. The special requirements of a wastewater treatment system for deployment during an emergency are discussed and a semi‐centralised system is recommended to serve 5000 refugees under a range of assumed loading conditions. Twenty‐three aerobic, anaerobic and natural systems are considered for secondary treatment and a process‐selection matrix is presented based around 16 evaluation criteria. A system layout is developed based around several sanitation facilities including sedimentation tanks connected to a centralised roughing trickling filter and an activated sludge unit, which provides optimal performance against the evaluation criteria. The system provides the required treatment performance in an easy‐to‐deploy, low‐cost compact installation.     

建筑施工4D++模型与4D项目管理系统的研究

本研究将4D模型理论和相应的CAD技术应用于建筑施工管理领域,研究新的4D++施工整体模型(4DSMM++)及其相应的数据管理机制。通过建筑物以及施工场地的3D整体模型与施工进度计划相链接,及其相关资源的信息集成,实现施工进度、人力、材料、设备、成本和场地布置的动态管理和优化控制,以及整个施工过程的可视化模拟,为建筑施工领域探索新的管理模式和方法,提供一个新的信息管理系统。     

以美国郊区-自维持生态住宅为例探讨小城镇住宅的能源策略

这是美国郊区的一座无耗能的自维持住宅。在住宅的整个建造过程中,建筑师对建筑的基地环境、材料、平面布置、节水、散热等问题进行了全面细致的设计。基于目前中国小城镇住宅市政设施普遍不完善的现状,笔者希望能够以这座脱离市政设施的建筑为例,对中国小城镇的住宅建造过程和使用过程中的能源进行最大限度的集约。     

基于BIM的高铁连续梁桥施工过程可视化管理技术研究

为研究信息化技术在高铁连续梁桥施工管理中的应用,以跨新沂河连续梁桥为工程背景,基于BIM技术开展了高铁连续梁桥施工过程可视化管理技术研究。基于BIM技术参数化设计特点,完善了桥梁结构及施工临时设施的参数化族库,建立了施工场地和桥梁结构模型; 开展了钢筋的碰撞检查和施工过程的碰撞分析,优化桥梁的设计方案; 基于BIM模型,模拟了施工现场布置方案,形成了3D施工文档用于可视化交底,并将BIM与施工监测结合,实现桥梁施工监测布置方案的可视化; 针对传统施工进度管理模式存在的问题,开展了高铁连续梁桥的4D(3D+时间)施工进度模拟与施工进度管理研究。结果表明:采用参数化建模策略提高了高铁连续梁桥的建模效率; 基于BIM的施工全过程可视化模拟不仅有利于施工方案的完善,同时降低了施工人员的理解难度; 4D进度管理可实现材料、设备、场地布置和施工进度的动态及可视化管理,有效提高了现场管理的精细化程度,研究成果为高铁桥梁施工过程可视化管理提供了可靠的技术支撑。     

基于突发公共卫生事件应急医疗设施的 城郊森林公园研究

面对新型冠状肺炎的突然暴发,国家快速启动应急医疗设施的建设。选址科学性和建设时效性是建设过程中面临的两大问题。利用城市绿地的防灾功能,通过平灾结合可在一定程度上缓解以上问题。通过比较发现,城郊森林公园在选址、规模、环境、基础设施、覆盖率等诸方面与应急医疗设施需求具有高度的契合性。将城郊森林公园纳入突发公共卫生事件应急预案,可以通过早期的合理选址、布局,预先勘探、铺设管网,加强污水、垃圾处理系统,合理规划康养功能等手段,大大提升灾时应急医疗设施建设的速度,并在一定程度上降低传染性疾病对人口和环境造成的危害。     

多因素耦合的新区综合管廊系统布局方法研究

综合管廊建设有利于保障城市安全、美化城市景观、提高市政设施综合承载能力和城市发展质量。新区实施综合管廊建设具有先天优势,如何在新区开发建设中科学系统地布局综合管廊,是新区市政基础设施规划建设面临的关键性课题。综合管廊系统布局受城市空间布局、建设用地开发强度、轨道交通和道路交通、市政管网系统等多因素影响,影响因素类型多,难以完全进行定量化评价。本文采用层次分析法,利用GIS空间叠加、缓冲区分析等功能,建立了一套半定量化的适用于分析新区综合管廊系统布局的评价体系,探索多因素耦合下的综合管廊系统布局,可为新区综合管廊系统布局规划提供技术思路。     

Optimal utilization of interior building spaces for material procurement and storage in congested construction sites

Congested construction sites, such as urban building projects, often have insufficient exterior space to accommodate all needed temporary facilities and material storage areas. Accordingly, interior building spaces need to be used for material storage while exterior space is left for temporary site facilities. Existing models of site layout and material logistics, however, do not support the utilization of interior spaces due to the complexity of interior space modeling. This paper presents the development of a new congested construction logistics planning (C2LP) model that is capable of modeling and utilizing interior spaces of buildings under construction to generate optimal logistics plans. The proposed C2LP model includes novel computational algorithms to model interior space allocation, complex space constraints, and impact of interior space utilization on activity scheduling. C2LP considers four types of decision variables, material procurement, material storage, facility layout, and scheduling of noncritical activities. The model is implemented by using multi-objective genetic algorithms to generate optimal logistics plans that provide optimal tradeoffs between minimizing total logistics costs and minimizing schedule criticality. The model is evaluated by using an application example to illustrate its capabilities in utilizing interior building space in the logistics plan of congested construction projects.     

基于改进重心法的装配式建筑生产基地的布局选址研究

在装配式建筑的发展过程中,区域性生产基地的布局选址是装配式产业发展的关键部分,不当选址会导致预制构件运输成本过高且局部发展不平衡等问题。通过研究相关选址文献,选择重心法并对其进行一些改进,一方面基于预制构件运输过程状况对重心法算法系数修正及调整,使得模型更加符合实际要求;另一方面结合聚类算法和模糊综合评价法,使模型满足多个基地布局选址要求。通过案例实证表明,改进的重心法模型既能实现多基地布局选址的要求,又能为装配式生产基地布局选址的相关决策提供一定的参考。     

回归功能的设计——北京飞机维修工程有限公司(AMECO)新建A380机库

AMECO新建A380机库是用于满足包括A380飞机在内的各种机型进行航线维修工作的机库。A380机库设计以满足航线维修功能为原则,提供多功能的、具有较高灵活性的飞机维修设施。设计从功能出发,工艺布局、设备配置、平面布置、建筑形象、结构设计均回归功能。通过寻找飞机维修机库建筑内在规律和功能特点,探讨在类似这种特殊功能的建筑中设计者应做的努力和思考。     

医疗卫生体系改革与城市医疗卫生设施规划

通过分析城市医疗卫生体系改革对于城市医疗卫生设施配置规划的影响,对城市医疗卫生设施的概念和配置指标的内涵进行了全新的诠释。寻求新时代条件下,城市医疗卫生设施规划的科学研究方法和空间布局模式,并提出相关政策的建议。     

Optimizing the planning of construction site security for critical infrastructure projects

Construction decisions can have a significant impact on the security level of critical infrastructures over their entire life cycle. Federal regulations require construction managers and security officers to consider all possible physical security measures to protect critical assets and classified information that reside onsite during the construction phase of critical infrastructure projects. This paper presents the development of an automated multi-objective optimization framework for the planning of construction site layout and security systems of critical infrastructure projects that provides the capability of minimizing overall security risks and minimizing overall site costs. The framework is developed in four main phases: (1) risk identification and system modeling, (2) security lighting optimization, (3) security-cost optimization, and (4) performance evaluation. The automated framework utilizes newly developed metrics for quantifying the security system performance and the impact of site layout planning on the effectiveness of the security system. The performance of the present framework is analyzed using an application example that demonstrates its capabilities in planning construction site security systems and generating optimal tradeoffs between minimizing security risks and minimizing overall site costs.