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.     

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.     

Generation of a construction planning from a 3D CAD model

In construction planning practice, increasingly 4D CAD system are applied for construction analysis and communication. Normally the planning expert is responsible for relating building components to construction activities. In this article we describe a method for automated generation of the construction planning. An algorithm is presented that derives the construction order from a solid model of the building. Experiences from a pilot study illustrate the differences between the real planning and the generated planning, and they show the limitations of the current implementation. Finally an outlook is presented on a more advanced planning system that includes contractor's specific knowledge for more accurate results.     

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。     

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.     

3D AR-based modeling for discrete-event simulation of transport operations in construction

This study proposes a 3D visualized modeling method for DES of transport operations in construction. The 3D simulation model built is a virtual field scene with property settings. AR technology was further applied to allow the use of a real-world image as the modeling background, which pictorially presents the current status of the real site as a visual basis for modeling. A typical transport operation was analyzed to determine the component classes for modeling. Then the visual representation and attributes of each modeling component class were proposed, along with modeling rules to build the 3D simulation model. A prototype system with STROBOSCOPE as the simulation engine was developed for presenting the proposed modeling method. A set of transformation rules was proposed for converting a 3D simulation model to a STROBOSCOPE input file. The system automatically extracts the simulation output and animates the 3D model to visually demonstrate the simulation result.     

基于虚拟现实技术的城市规划仿真系统开发研究

三维虚拟现实系统的发展,使城市规划的表现手段从原有的传统模型工艺提升到全新的数字技术阶段。本文以厦门市城市三维模型地理信息系统的创建为例,介绍了基于Vrmap与Creator的三维场景构建流程,虚拟现实集成方法以及面向城市规划的三维可视化系统设计方案,探讨了三维虚拟现实系统开发中的关键技术问题。     

Integrating 3D visualization and simulation for tower crane operations on construction sites

Most high-rise building construction projects rely on tower cranes to perform lifting and hoisting activities. In practice, tower cranes are managed based on demand, urgency, and prioritized work tasks that must be performed within a set period of time in the field. As a computer tool, simulation has proved to be effective in modeling complex construction operations and can be a substantial help in aiding practitioners in construction planning. However, the use of simulation has fallen far below its maximum potential due to a lack of appropriate support tools which would allow construction managers to use simulation tools for themselves. Special purpose simulation (SPS) and 3D visualization of simulated operations are two potential means that enable domain experts, who are knowledgeable in give domains, but not familiar with simulation, to easily model an operation within their domain and analyze the simulation results. This paper presents a practical methodology for integrating 3D visualization with SPS for tower crane operation. An integrated system was built in a 3D Studio MAX environment and tested in the construction of the new civil and environmental engineering building at the University of Alberta. This paper demonstrates that 3D visualization is helpful in the verification and validation of simulation results, and can effectively communicate the essence of a simulated operation, thus improving the accessibility of simulation as a decision making aid.     

3D打印建筑的发展与展望

论述了3D打印技术给建筑行业建设项目全过程管理带来的机遇和挑战,根据目前国内外3D打印建筑的发展现状,对3D打印建筑与传统建筑业进行了对比分析,提出了3D打印建筑的优势以及目前存在的一些问题,最后对3D打印建筑的未来进行了展望。     

3D structural component recognition and modeling method using color and 3D data for construction progress monitoring

Construction progress monitoring has been recognized as one of the key elements that lead to the success of a construction project. By performing construction progress monitoring, corrective measures and other appropriate actions can be taken in a timely manner, thereby enabling the actual performance to be as close as possible to the desired outcome even if the construction performance significantly deviates from the original plan. However, current methods of data acquisition and its use in construction progress monitoring have tended to be manual and time consuming. This paper proposes an efficient, automated 3D structural component recognition and modeling method that employs color and 3D data acquired from a stereo vision system for use in construction progress monitoring. An outdoor experiment was performed on an actual construction site to demonstrate the applicability of the method to 3D modeling of such environments, and the results indicate that the proposed method can be beneficial for construction progress monitoring.     

各向异性砂土宏微观特性三维离散元分析

各向异性对砂土强度和变形特性有显著的影响,为了研究各向异性砂土的宏微观特性,基于三维离散元法,对7个不同沉积角的试样进行了一系列的三轴模拟试验。利用"Clump"命令生成近似椭球形状颗粒,并且采用三维抗转动模型来模拟颗粒间的抗转动能力。离散元模拟结果与已知室内试验结果吻合很好。结果表明:随着沉积角的增大,偏应力和轴向应变的关系逐渐由应变软化向应变硬化发展。沉积角较小的试样剪胀性更强并且容易到达临界状态,颗粒组构–应力联合不变量(表征颗粒长轴组构张量和应力张量的相对角度)的值接近于-1,且颗粒长轴组构各向异性先增大后减小;然而对于沉积角较大的试样,在轴向应变50%处,仍不能达到临界状态,并且联合不变量的值大于-1,颗粒长轴组构各向异性先减小后不断增大。对于法向接触组构,组构主轴方向迅速向应力主轴方向偏转,组构各向异性的演化规律与偏应力随轴向应变的演化规律相似。     

土木建筑虚拟仿真实验教学中心建设与实践

河南工业大学土木建筑虚拟仿真实验教学中心坚持以服务本科教学为核心，以培养学生创新意识和创新能力为宗旨，以粮油仓储建筑为特色，将实验教学与科学研究、工程实践相结合，利用虚拟现实、计算机网络以及多媒体等技术建立了"基础型、专业型、特色创新型"三层次的土木建筑虚拟仿真实验教学资源体系。创新虚拟仿真实验教学方法，增强学生创新精神和实践能力，为本科实验教学、实习实训和援外培训等教学与对外交流合作提供了丰富的虚拟仿真资源。     

公路隧道前置式洞口工法的三维数值分析

以宁(南京)淮(安)高速公路老山公路隧道为依托,对洞口前置式洞口施工过程的力学行为进行了三维数值模拟,分析了洞口段围岩和前置式支护结构体的位移场、应力。计算结果表明:前置支护结构及两洞间土体对洞口山体的支撑作用明显,既可大大减少洞口的边、仰坡开挖量保护洞口环境,又能有利于洞口段稳定和洞口施工安全。     

Stereoscopic 3D exploration of freeform architecture

As freeform architecture becomes popular, the observation method for complex geometries is also becoming important. In particular, stereoscopic 3D is one of the most useful approaches to explore 3D space realistically with extrusion and depth feelings. In this work, we propose a stereoscopic 3D exploration to observe an internal space structure of freeform architecture effectively. For a visually comfortable stereoscopic 3D navigation, we analyze causes of visual discomfort and control perceived depth by adjusting virtual camera separation and virtual screen depth in a stereo scene. Since a user notices rapid changes of a scene, we measure JND (Just Noticeable Difference) for the optimal changes of virtual camera separation and virtual screen depth. For the camera movement in complex and curved pathways, we use automated navigation utilizing cubic Bézier curves. During the navigation, the camera parameters are controlled automatically in order to produce visually comfortable stereoscopic 3D scenes. We also performed a user study to verify the effectiveness of the proposed explorations using famous freeform architectural models such as the Guggenheim Museum and the Jubilee Church.     

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.     

三维辅助的CAD管线入库与检查系统的实现

在传统的测绘工作中,管线的数据入库与检查是在二维图形系统中完成的。随着技术的发展,这种模式已经显示出了在空间关系表达上的弊端,因此本文探讨了在三维空间中对管线进行辅助质量检查的模式。文中的系统采用了二三维结合的方法,即在二维CAD模块中进行管线的绘制及属性录入工作,并在三维视图中同步显示三维管线。同时开发了管线碰撞检测功能,可以迅速发现数据库中的空间逻辑错误,并通过三维的方式直观的提醒用户。该系统通过实际运用,三维显示速度快,检查结果准确,为管线数据质量的提高提供了有效的工具。     

基于X3D的三维虚拟技术的研究

为了满足用户对虚拟会展展馆个性化的需要,本文提出了如何建立基于X3D虚拟现实技术的三维虚拟展馆定制系统。该系统具有较好的实用性,既为真实展馆的定制提供仿真的平台,又为如何建立虚拟展馆提供了范例。     

Integrated construction of negative pressure medical cabin using 3D printed concrete

3D打印混凝土可实现数字设计、一体化快速打印建造成型，具有整体性好、气水密闭、保温隔热、灵活定制、经济耐用以及安全可靠等技术优越性。基于负压医疗标准和技术参数，提出一种可拼接组装、快速就位、安全耐久的3D打印混凝土负压医疗舱空间胶囊结构。基于打印工艺和材料参数开展数值模拟，分析了负压医疗舱结构在承载能力极限状态、正常使用极限状态和建造安装阶段的结构性能，并通过模态分析研究了不同激励工况下的结构振动舒适度。结果表明：3D打印胶囊型混凝土负压医疗舱最大拉压应力小于其抗拉与抗压强度，具有良好的安全性；正常使用极限状态下结构变形满足使用限定条件，适用性良好；负压医疗舱吊装过程中结构具有很好的安全储备，施工安全可行。与传统装配式负压病房相比，3D打印混凝土负压医疗舱的一阶竖向自振频率提高了99.95%，更不易在日常使用工况下产生激励共振。在行走激励下，3D打印负压医疗舱均满足振动舒适度要求；在奔跑激励下，3D打印负压医疗舱的加速度响应处于振动有感阶段；而传统负压舱病房在行走激励下难以满足振动舒适度要求，在奔跑激励工况下的加速度响应超出人体对于振动响应的忍受范围。     

3D打印混凝土负压医疗舱一体化建造技术研究

3D打印混凝土可实现数字设计、一体化快速打印建造成型,具有整体性好、气水密闭、保温隔热、灵活定制、经济耐用以及安全可靠等技术优越性。基于负压医疗标准和技术参数,提出一种可拼接组装、快速就位、安全耐久的3D打印混凝土负压医疗舱空间胶囊结构。基于打印工艺和材料参数开展数值模拟,分析了负压医疗舱结构在承载能力极限状态、正常使用极限状态和建造安装阶段的结构性能,并通过模态分析研究了不同激励工况下的结构振动舒适度。结果表明：3D打印胶囊型混凝土负压医疗舱最大拉压应力小于其抗拉与抗压强度,具有良好的安全性;正常使用极限状态下结构变形满足使用限定条件,适用性良好;负压医疗舱吊装过程中结构具有很好的安全储备,施工安全可行。与传统装配式负压病房相比,3D打印混凝土负压医疗舱的一阶竖向自振频率提高了99.95%,更不易在日常使用工况下产生激励共振。在行走激励下,3D打印负压医疗舱均满足振动舒适度要求;在奔跑激励下,3D打印负压医疗舱的加速度响应处于振动有感阶段;而传统负压舱病房在行走激励下难以满足振动舒适度要求,在奔跑激励工况下的加速度响应超出人体对于振动响应的忍受范围。     

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.