Trends of 4D CAD applications for construction planning

Since the early 1990s, there has been a growing interest in four‐dimensional computer aided design (4D CAD) for construction project planning. Commercial 4D CAD applications are becoming more accessible and the use of this technology allows the construction planner to produce more rigorous schedules. A review of the technical competencies of these packages highlights that most of the commercially available packages concentrate on the use of 4D CAD simulations for aesthetic visualization purposes. Very few packages offer the ability to carry out analytical tasks on the developed simulation and this is often left to the interpretation of the user. A thorough appraisal of emerging research developments in 4D planning highlights that this technology is employed for various applications; however, the amount of detail required in a 4D simulation is still ambiguous. A model is proposed to determine the attributes required for use with each of the various applications of 4D CAD simulations. Finally, various lines of future research are highlighted, including the need for improved use of data exchange standards and the automation of linking the construction tasks to the 3D CAD model.     

Virtual construction of architecture using 3D CAD and simulation

3D modeling and computer simulations provide new ways for architecture students to study the relationship between the design and construction of buildings. Digital media help to integrate and expand the content of courses in drafting, construction and design. This paper describes computer-based exercises that intensify the student's experience of construction in several courses from sophomore to senior level. The courses integrate content from drafting and design communication, construction, CAD, and design.Several techniques are used to strengthen students' awareness and ability in construction. These include:

• •Virtual design–build projects in which students construct 3D CAD models that include all elements that are used in construction.
• •Virtual office in which several students must collaborate under the supervision of a student acting as project architect to create a 3D CAD model and design development documents.
• •Virtual sub-contracting in which each student builds a trade specific 3D CAD model of a building and all of the trade specific models must be combined into a single model.
• •Construction simulations (4D CAD) in which students build 3D CAD models showing all components and then animate them to illustrate the assembly process.
• •Cost estimating using spreadsheets.

These techniques are applied and reapplied at several points in the curriculum in both technical laboratory courses and design studios.This paper compares virtual construction methods to physical design–build projects and provides our pedagogical arguments for the use of digital media for understanding construction.     

4D CAD model updating using image processing-based construction progress monitoring

For a four-dimensional (4D) computer-aided design (CAD) model to be useful for users throughout a construction project, the model must be updated in a timely and accurate manner during the construction. Only when it has been properly updated can the 4D CAD model reflect the real progress of a construction site to inform managerial decision making. However, updating a 4D CAD model is time-consuming and labor-intensive because the full updating process, from site data acquisition to 4D model regeneration, is typically conducted manually. This difficulty in updating a 4D model discourages industry practitioners from actively adopting 4D models. This paper presents an image processing-based methodology for the automatic updating of a 4D CAD model. Characterized by 3D CAD-based image mask filters, color-based noise removal, and area-based progress calculation, the image processing approach provides as-built schedule information. The schedule information is then automatically integrated with an existing 3D CAD model in batch-processing modes to produce the updated 4D CAD model. The proposed methodology was applied and verified in a cable-stayed bridge construction project and is expected to facilitate the wider use of 4D CAD models in the construction industry.     

4D CAD技术在施工管理中的应用研究

4D CAD技术属于计算机技术在工程施工领域应用的一项新技术,本文作者通过论述4D CAD技术的发展,分析了4D CAD技术在施工管理中的优势。通过对比分析常见4D CAD软件的基本功能,结合一座大型桥梁工程的施工实践,具体说明4D CAD技术的优点和应用障碍。最后,提出4DCAD技术发展的趋势和方向。     

Automated construction progress measurement using a 4D building information model and 3D data

Accurate construction progress measurement has been shown to be critical to the success of a building project. However, the methods of automated construction progress measurement proposed in previous studies have certain limitations because of incomplete data sets. The main objective of this research was to develop an accurate, essentially fully automated method for construction progress measurement using a 4D BIM in concert with 3D data obtained by remote-sensing technology. The proposed method consists of three phases: alignment of the as-built data with the as-planned model, matching of the as-built data to information in the BIM, and revision of the as-built status. The accuracy of the proposed construction progress measurement method was validated using 3D data obtained from an actual construction site, thereby demonstrating that construction progress can be effectively measured. The results of the proposed progress measurement methodology can be used as input for construction progress visualization and schedule updating.     

GIS三维模型在城市规划中的应用

以昆明富民为例,利用GIS技术对城市规划三维建模的实现方法进行了研究,在发展城市建设及旅游,保护自然环境需求的前提下,依据三维模型对研究区城市的功能结构布局进行合理的规划,结果表明,利用GIS三维建模可以为城市规划工作提供科学的决策依据。     

谈3D模型在施工中的应用

简要介绍了SmartPlant Review 3D设计软件的功能,应用范围及优势,着重阐述了SmartPlant Review 3D模型在施工中的集成化应用、快照应用、协作应用等多种用途,指出该设计软件能够大大提高工程建设生产效率,值得推广。     

An object-based 3D walk-through model for interior construction progress monitoring

The complicated nature of interior construction works makes the detailed progress monitoring challenging. Current interior construction progress monitoring methods involve submission of periodic reports and are constrained by their reliance on manually intensive processes and limited support for recording visual information. Recent advances in image-based visualization techniques enable reporting construction progress using interactive and visual approaches. However, analyzing significant amounts of as-built construction photographs requires sophisticated techniques. To overcome limitations of existing approaches, this research focuses on visualization and computer vision techniques to monitor detailed interior construction progress using an object-based approach. As-planned 3D models from Building Information Modeling (BIM) and as-built photographs are visualized and compared in a walk-through model. Within such an environment, the as-built interior construction objects are decomposed to automatically generate the status of construction progress. This object-based approach introduces an advanced model that enables the user to have a realistic understanding of the interior construction progress.     

基于混合模型的建设规划研究

随着时空大数据在各行各业运用越来越来广泛,通过对在校大学生位置信息的采集,针对校园道路等公共设施建设不合理的问题,对学生群体日常位置轨迹进行分析,从聚类角度出发,运用一种基于高斯混合模型(GMM)和DBSCAN算法的混合模型对位置数据进行处理分析,通过混合模型对位置数据进行分层处理再聚类处理,确定学生群体日常活动核心区域以及路径,对校园道路等公共设施建设具有一定的指导意义。     

Real-time ergonomic risk assessment in construction using a co-learning-powered 3D human pose estimation model

Work-related musculoskeletal disorders pose significant health risks to construction workers, making it essential to monitor their postures and identify physical exposure to mitigate these risks. This study presents a novel framework for real-time ergonomic risk assessment of workers in construction environments. Specifically, this study develops a lightweight human pose estimation (HPE) model with a residual log-likelihood estimation head and adopts pose-tracking technology to enable real-time recognition of workers’ three-dimensional (3D) postures. In particular, this study proposes a novel co-learning method that enables the HPE model to learn two-dimensional (2D) and 3D features from multi-dimension datasets simultaneously, substantially enhancing the model's ability to capture 3D postures from 2D images. The proposed framework facilitates real-time ergonomic risk assessment, reducing potential risks to construction workers and offering promising practical applications.     

信阳市新农村规划建设模式研究

对信阳市市域城镇化背景下的新农村规划建设存在的问题进行分析,探讨新农村规划建设复合模式的路径选择。针对信阳市新农村建设情况,探索符合可持续发展要求的新农村规划建设模式,并提出相关建议。     

An evaluation of the applicability of 4D CAD on construction projects

4D CAD models that integrate physical 3D elements with time, have been used to visualize construction processes in several projects worldwide. 4D models have been used and have been shown to have benefits over processes that span the entire lifecycle of a project such as collaboration with stakeholders, making design decisions, assessing project constructability, identifying spatial conflicts in construction and so on. Despite these benefits, several organizational and project-specific barriers have hindered the widespread adoption of 4D CAD. In order to reconcile the theoretical benefits of 4D models with the practical difficulties faced in implementation, there is an urgent need to explore the implementation of 4D models on construction sites as well as the perceptions of intended users/beneficiaries towards this implementation. This paper aims to address this need and contribute to our understanding of how 4D models must be introduced, positioned and implemented on construction sites, so as to maximize both their acceptability and their usefulness. We describe two 4D models of infrastructure projects and two 4D models of commercial projects that have been built and implemented. Through a process of structured and unstructured interviewing the paper gauges the response of project participants across various organizational levels on each of these projects as to the usefulness of 4D in project planning and control. Through qualitative and statistical analysis of the data we establish that 4D CAD is likely to be most beneficial in the project shaping or planning stage and in the construction stage. In the project shaping stage, 4D CAD is likely to be particularly useful in communicating construction plans and processes to clients, while during the construction phase, 4D CAD is likely to be particularly useful in comparing the constructability of work methods visually in order to detect conflicts or clashes, and as a visual tool for contractors, clients, subcontractors and vendors to review and plan project progress. Further, upper management and site workers are more likely to use and derive benefits from the visualization of processes using 4D given their lack of site related knowledge or skills, while construction professionals who are more construction-savvy are more likely to appreciate and benefit from the analytical and planning aids that 4D simulations provide during the construction phase. However, it is likely that despite these benefits 4D CAD models might not diffuse through the construction industry unless 4D modelling and analysis is integrated into existing project planning approaches. The paper concludes with a brief discussion on future 4D software development that seeks to bring about such integration and leverages the benefits of 4D CAD to bring about improved operational efficiencies on construction sites.     

A simplified 3D model for tunnel construction using tunnel boring machines

This paper includes a presentation of a simplified three-dimensional numerical model for the prediction of soil movement induced during tunnel construction using tunnel boring machines (TBM). The model is based upon the generalization of the convergence-confinement concept to 3D tunnel construction. It uses two parameters (L_dec and α_dec) which stand for the length of the unlined zone and the partial stress release, respectively. The value of the parameter L_dec can be taken equal to the tunnel diameter, while the value of α_dec can be determined by fitting the model to empirical formula, and then adjusted based on settlement registered during tunnel construction.The capacity of the model is illustrated through an application to a shallow tunnel in soft soil. The comparison of the numerical results to those suggested by different authors shows good agreement.     

液压三维管道布置CAD系统

介绍在微机上开发的液压系统三维管道布置的计算机辅助设计系统。该系统利用面模型和参数绘图技术，建立液压元部件图库，并配之坐标和菜单驱动系统操作图形库，即可实现三维管道系统的设计、模拟装配并可生成该液压系统二维工程图及三维装配图。     

基于三维模型技术的城市地铁施工期地面沉降分析

应用GIS专业软件ArcView中的空间分析和三维分析模块,以南京地铁某车站施工为例,采用水准测量法和Peck公式法分别进行地表沉降离散数据采集,然后选取反距离权重法（IDW）进行空间插值拟合出地面变形的DEM趋势面,并进行综合三维分析,以更加直观、生动的方式为项目决策者和施工人员提供技术支持和决策依据。     

Decision model for planning material supply channels in construction

Material supply-related decisions strongly affect economic performance of construction projects. To facilitate planning, the authors put forward a mixed integer linear programming model for optimizing supplies of materials or components that are consumed irregularly. The model's objective function is minimizing the total inventory management cost. As material prices change over time and cannot be predicted with certainty, they are expressed as fuzzy values with triangular membership functions. The planning horizon is divided into units of time to allow for seasonal changes and scope variations that affect consumption of materials. The model enables the user to determine economic order quantities for consecutive periods of construction works and to select most economical supply channels of a particular material/component. The model allows for material/component substitution. Substitutes may differ in level of prefabrication and thus in costs of on-site processing. To solve the problem the fuzzy model is converted into a three-objective linear program with crisp coefficients. An example illustrates benefits of using the proposed approach in reducing the total inventory cost.     

基于多智能体技术的景观规划模型建构

作为复杂系统分析与模拟的思想方法与工具的多智能体模型可以模拟景观空间与其中行人活动的相互影响进而辅助景观规划设计,本文探索了这种创新的思维方式和方法:详细阐述了基于多智能体技术的景观规划模型的基本原理、规则的设定和参数的依据,建构了这种新的景观规划思路。     

Visualizing high-rise building construction strategies using linear scheduling and 4D CAD

Project teams face ever increasing pressure to deliver projects as quickly as possible. To meet these demands, contractors are faced with the need to explore various construction strategies in order to meet delivery dates, and to assure themselves as to the achievability and quality of a schedule. Various visual representations of a project's schedule and associated information combined with visual representations of the project in progress, i.e. 4D CAD, can assist with these tasks of identifying effective construction strategies for shortening project duration, assessing their workability, and judging schedule quality. Such visual representations aid communication amongst project staff and facilitate brain-storming, and, implemented well they can provide clear, fast, and multi-dimensional feedback to the project team. In this paper, we describe aspects of our work which is directed at formulating a dynamic visualization environment that links 3D CAD, a generalization of traditional CPM which embraces linear scheduling, dual product representations (scheduling and CAD system) and their mapping onto each other, and schedule and CAD graphics in a manner which facilitates the relatively rapid exploration of alternative construction method and scheduling strategies for large scale linear projects (e.g. high-rise buildings, bridges, etc.). Requirements of such an environment include quickness, treating scale, working at multiple levels of detail, dealing with design variability, and realistic representation of the work. Use is made of a realistic example to highlight aspects of our approach and identify important issues that must be addressed if a visualization environment useful for construction professionals is to be developed.     

An object-oriented model for planning and control of housing construction

A practical object-oriented model for the planning and control of housing construction is presented that can generate efficient schedules and determine the time and cost performance of a housing project at three levels: (i) entire project, (ii) particular housing unit and (iii) an individual subcontractor. The model comprises five major components: (1) input module, (2) scheduling module, (3) database module, (4) control module and (5) reports module, and incorporates 18 classes that are designed to address the main requirements in planning and control of housing construction. The model is implemented as a user-friendly prototype software system using Visual C++ 6.0 and Microsoft Foundation Class (MFC). The prototype software is named ‘Residential Planner’, and runs in Windows 2000 and NT. An example of an application is analysed to illus8 trate the use of the developed model and demonstrate its practical features.     

基于图层自动识别算法的BIM结构模型生成方法研究

本文提出一种在图层自动识别算法基础上依据平面图和列表信息创建结构信息模型的方法。利用构件的绘制特征和构件与其标注的匹配算法实现结构构件的自动识别,读取构件列表和楼层标高表信息,匹配平面图的识别信息与列表信息; 通过轴网和楼层高度,获取构件三维坐标系位置; 建立SQLite数据库,存储生成BIM模型所需的数据信息; 采用C#语言和Visual Studio2017开发工具,基于Revit提供的函数库进行二次开发,经实例验证该方法能够快速、准确地实现从CAD图纸到BIM模型的自动转换,从而提高转换的自动化程度和准确度,其转换准确率约为96%。