Decision support for construction method selection in concrete buildings: Prefabrication adoption and optimization

Prefabrication offers a substantial opportunity to improve projects' sustainable performance. However, decisions to employ prefabrication are still largely based on familiarity and personal preferences rather than rigorous data. Methodical assessments of an appropriate construction method for a concrete project have been found deficient. This paper presents an objective and transparent tool, the Construction Method Selection Model (CMSM), which is designed to aid building team members during early project stages in evaluating the feasibility of prefabrication and exploring an optimal strategy to apply prefabrication in concrete buildings. The model is divided into two sequential levels: the strategic level and the tactical level, respectively. The Simple Multi-Attribute Rating Technique (SMART) is used in the first level for preliminary feasibility evaluation of prefabrication. The Multi-Attribute Utility Theory (MAUT), which considers uncertainty and risk attitude, is employed in the second level to assess to what degree of prefabrication is appropriate for the project at hand. A detailed case study through in-depth personal interviews with four decision makers is presented to illustrate the use of the model and to demonstrate the capability of the model. The results show that the proposed model is a useful and effective decision-making tool for prefabrication adoption and optimization in concrete buildings.     

Sustainability assessment of flooring systems in the city of Tehran: An AHP-based life cycle analysis

In recent years, numerous attempts have been made to reduce the global environmental and associated socio-economic impacts of construction activities to achieve sustainable development goals. A sustainable system or activity refers to an eco-friendly, cost effective and socio-politically viable solution. This paper utilizes triple-bottom-line (TBL) sustainability criteria for the selection of a sustainable flooring system in Tehran (Iran). Three types of block joisted flooring systems – concrete, clay, and expanded polystyrene (EPS) blocks – have been investigated using life cycle analysis (LCA). Proposed approach provides a comprehensive evaluation system based on TBL criteria that are further divided into thirteen sub-criteria. It includes: (1) Environmental concerns (resource depletion, waste and emissions, waste management, climate change, environmental risk, embodied energy and energy loss); (2) Economic concerns (material cost, construction cost, and occupation and maintenance cost); and (3) Socio-political issues (social acceptance, vulnerability of area, and building weight). Analytical hierarchy process (AHP) is used as a multi-criteria decision making technique that helps to aggregate the impacts of proposed (sub)criteria into a sustainability index (SI) through a five-level hierarchical structure. Integration of AHP and LCA provides a framework for robust decision making that is consistent with sustainable construction practices. A detailed analysis shows that the EPS block is the most sustainable solution for block joisted flooring system in Tehran.     

“双全法”在高校基建投资控制中的应用与研究

随着高校建设规模扩大,基建投资成为高校管理工作的重点.从基建管理者角度,探讨如何用“全员教育”和“全环节控制”的“双全法”控制工程造价.从设计方案的确定、施工队伍的选择、材料的采购供应、施工过程的控制、预结算的审核等方面说明“双全”法在基建投资管理中的具体运用和重要意义,阐述以设计阶段为重点,技术与经济相结合的工程造价全过程动态控制方法.结合高校基建的特点,强调“阳光招标”的重要性.     

Towards adoption of prefabrication in construction

There is an urgent issue on huge quantities of wastage generation in construction. There should not be lack of environmental support from construction stakeholders. The current implementation of prefabrication seems unable to provide satisfactory results to the construction industry. This paper provides a feasibility analysis in adopting prefabrication in construction activities. Advantages, hindrances and future development on prefabrication's applications are provided based on a questionnaire survey. The suitability in adopting prefabrication of various project types is also examined. Furthermore, a financial analysis is also investigated by a local case study. It found that wastage generation can reduce up to 100% after adopting prefabrication, in which up to 84.7% can be saved on wastage reduction.     

Discussion of paper

In the spring of 1993, the Utah Special Improvement District project was initiated to improve sidewalks, curb and gutters, and driveway approaches (aprons) in Salt Lake City. One of the critical problems faced during this project was how to recommend the most appropriate treatment decision at the roadway improvement job sites. Therefore, the research was conducted to demonstrate the use of an expert system on a portable computer at the construction job site. A prototype Portable Inspection Expert System (PIES) was developed based on the following factors: displacement, surface condition, water effect, tree root effect, and condition of adjacent sections. PIES can decide if replacement, jacking, or do nothing treatment of concrete sections is required.

PIES program was developed by using “KnowledgePro Windows” expert system shell, and installed in “Dauphin DTR-1” pen-based portable computer. One of the major benefits of using an expert system on a portable computer is that it can combine the necesary information on the distress condition of the facilities and help the inspectors make appropriate decision at construction job sites. PIES had been tested with two engineers and a follw-up survey was conducted after the test. Feedback from the survey was analyzed to improve limitations. The current inspection process for the Utah Special Improvement District project was improved by using a consistent decision rule of PIES.     

装配式建筑施工阶段碳排放测算研究

根据碳排放系数法构建模型,结合工程量清单对装配式建筑施工阶段的碳排放进行测算, 探讨预制率对施工阶段碳排放的影响, 深入探究工程造价、总建筑面积与碳排放总量的关系。以漳州某住宅楼为例, 探讨施工阶段碳排放的排放规律并提出减排路径。 结果表明: 施工阶段的碳排放主要来自一般土建工程;单位面积的碳排放在 671 kgCO2/m2左右波动,单位造价的碳排放在 2749.33 kgCO2/万元左右波动; 混凝土工程和钢筋工程的碳排放随着预制率的升高而增加; 碳排放总量与工程造价、建筑面积存在显著的线性关系。     

浅谈公路桥梁上部结构造价计算要点

从预制安装简支梁、现浇混凝土连续梁、悬浇混凝土连续梁三方面对公路桥梁上部结构造价计算要点进行了介绍,指出预算员应熟悉各种桥梁的施工工序和施工时所用的设备,从而提高工程概算的准确性和编制质量。     

The impacts of fabrication systems on 3D concrete printing building forms

Recently, 3D concrete printing (3DCP) technology starts entering the market from factories and laboratories, contributing to the creation of new construction methods and architectural forms. However, since the technologies of most 3DCP institutions are independently developed, there is a lack of consensus in terms of construction methods and development approaches in the industry. In this paper, based on 42 3DCP architectural works completed in last five years, a quantitative analysis was made to evaluate the impacts of the fabrication system on 3DCP building forms. The paper introduced three criteria, including Workspace Index, Geometric Complexity Index, and Tectonic Prospect Index, analyzing and answering the discussions about “adopting in-situ printing or prefabrication”, “using gantry printers or robotic arms” from the perspective of architectural form. By analyzing specific construction methods and design strategies in these projects, the research summarized three development trends, “mobile equipment, algorithmic structure, and intelligent construction”, which will affect the future development of 3DCP building forms. Finally, the paper discussed the advantages, limitations, and potential of four different 3DCP fabrication systems, expecting to point out the directions to further optimize each system and realize more diverse 3DCP buildings.     

Langzeitverhalten geklebter Bauteile aus Holz und hochfestem Beton bei natürlichem Klima

Longterm‐behavior of glued full‐scale specimens made from wood and high performance concrete at natural climate conditions The advantages of the construction materials wood and concrete could be used effectively in wood‐concrete‐composite constructions. The composite structure shows optimized load carrying capacity, a better vibrational behavior, higher noise protection and a higher thermally activatable mass in comparison to constructions that are entirely made from wood. Mechanical fasteners or form fitting connections are state‐of‐the‐art for connecting timber to concrete. This leads to more or less flexible bond. By using the adhesive technology a ”rigid bond“ can be achieved and it is possible to combine the advantages of a ”dry construction method“ with the advantages of the prefabrication. The questions of the production technology and the short‐term behavior of glued wood‐concrete composite constructions were answered yet at the department of timber structures at the University of Kassel. Knowledge of long‐term behavior was missing for an application in construction practice. This was studied in the last three years in detail. The experimental und numerical investigations on full‐scale specimens and the conclusions for a practical application are reported in the following article.     

北京射击馆预制清水混凝土外挂板施工技术

北京射击馆为2008年北京奥运会射击比赛用馆.以北京射击馆为例,介绍了预制无装饰清水混凝土外挂板的设计、预制和安装技术.工程施工前,对预制清水混凝土外挂板的制作、模板、钢筋骨架等制定了验收标准.根据外墙各部位尺寸、门窗位置,对板块尺寸、细部构造进行了深化设计;同时采取合理的配合比、原材料、预制方法和养护方法确保了混凝土颜色、表面观感、质量符合要求.安装过程中通过精确的测量放线确定外挂板的安装位置,从下向上依次逐层安装顺序完成了预制板的安装工作.     

四川德阳换流站电缆沟创新施工技术

结合工程经验,介绍了施工技术创新流程与具体步骤,并通过四川德阳换流站电缆沟施工实例,结合设计与规范要求,为提高电缆沟的整体观感质量和效果,通过采用镜面混凝土技术,模板预制工艺,电缆沟美观及其他细节技术创新,确保了工程质量,取得了良好的社会和经济效益。     

功能型聚羧酸外加剂在混凝土预制构件中的应用

建设施工使用的混凝土预制构件产品种类资源十分丰富,常见的有在地铁工程、西气东输工程等隧道施工中高精度钢筋混凝土盾构管片的使用,在城市桥梁建设工程中预制拼装节段梁的使用,在高速铁路施工过程中预制清水混凝土饰面板的使用等。随着建筑质量需求的逐渐提升,混凝土预制构件的质量已经成为建筑领域备受关心的问题。     

全面造价管理与绿色建筑

全面造价管理是面向21世纪的造价管理方法,目前它是集全过程、全要素、全风险和全团队为一体的造价管理。但随着可持续发展战略和构建和谐社会,实现人与自然和谐相处理念的提出,随着绿色建筑概念的产生,建设项目的全面造价管理思想受到了巨大的冲击和影响——全面造价管理应该站在更高的层次,站在整个社会的角度,尽量降低项目对社会和环境的不良影响。这样全面造价管理的内涵就更加充实了,不仅包括前述四个方面的造价管理,还应当包括可持续发展的造价管理,只有这样,才能综合实现建设项目的经济效益、环境效益和社会效益。     

Design issues of using prefabrication in Hong Kong building construction

Prefabrication techniques have been adopted for the last two decades in public housing projects in Hong Kong, but the use of prefabrication in the private sector was encouraged only after the implementation of the Joint Practices Notes which promote its use. Although previous studies acknowledge the environmental benefits of using prefabrication, only a few studies have addressed sustainable design concepts (closed‐loop) in the adoption of precast construction. A questionnaire survey was administered to experienced Hong Kong construction professionals, and case studies of recently completed building projects were compiled to ascertain the use of prefabrication with reference to life cycle approach. The findings revealed that prefabrication, combined with modular design and standard components, saved time and construction/design costs, as buildings systems were used across projects. However, in some projects, specific site conditions restricted the use of similar prefabricated building systems across projects. Surprisingly only a few participants addressed life cycle design concepts such as design for deconstruction when adopting precast construction. Also, although it is common knowledge that flexible and demountable prefabricated building systems would result in efficient use of resources, their use is seldom practised in Hong Kong.     

浅谈建筑装配式混凝土结构工程的施工要点

建筑装配式混凝土结构工程施工可分为工厂预制和现场施工两部分,具有结构安全、施工快捷、节能省地、绿色环保等优点,是实现建筑工业化的重要途径。本论文以建筑装配式混凝土结构工程为基本研究对象,对其具体工程施工要点进行了一定的探讨和分析。     

过江隧道混凝土沉管预制新技术

越来越大的运用需求和跨越更大水深、更宽阔海峡的发展趋势,使混凝土沉管隧道的传统预制技术面临许多挑战。发展更高效率、更灵活和更可靠的预制技术具有重大意义。结合典型工程实例,阐述混凝土沉管的预制新技术:移动干坞技术,分部浮态浇注技术,工厂化、全断面节段浇注技术。分别介绍了各预制方法的技术特点、施工工艺、优势及不足。新技术的应用发展和丰富了沉管隧道的设计和施工技术。     

大跨径混凝土拱桥拱上立柱接头施工质量控制

阐述了广西柳州市三江县中山大桥拱上立柱预制与现浇接头施工,介绍了接头模式、预制及现浇立柱端头处理、接头对接、接头混凝土施工控制要点,结合实际提出了对缺陷处理的措施,从而为实际工程施工积累经验。     

跨径30m箱梁的预制

介绍了桥孔跨径为30 m的标准预应力混凝土箱梁预制的主要过程,从梁场建设,门吊选型,普通钢筋和预应力钢绞线制安,后张法施加预应力施工等方面进行了详细论述,提供了此类箱梁的施工方法和技术支持,对保障箱梁预制质量、降低成本、提高效率具有重要意义。     

建筑固体废弃物治理全生命周期环境影响评价—以废旧粘土砖为例

为定量评价建筑固体废弃物治理的环境影响,基于生命周期评价（LCA）理论和建筑工程环境表现评价系统（BEPAS）,综合考虑废弃物治理过程的环境代价以及再生材料的环境收益,以净环境代价为指标,建立了建筑固体废弃物治理环境影响评价框架。根据实际案例,定量评价了废旧粘土砖几种典型治理方式的环境影响,结果表明:填埋的净环境代价较高,其次是重复利用,而再生利用的代价相对较低;在再生利用方式中,净环境代价从小到大依次为水泥混合料、混凝土砌块原料、免烧砌筑水泥原料、混凝土骨料、烧砖瓦原料,其中烧砖瓦原料的净环境代价为正值,即所得到环境收益不足以弥补其环境代价。     

建设项目工程造价管理信息系统构建及运用

随着我国对建设项目工程造价管理信息系统构要求的提高,建立一套科学完整的“建设项目工程造价管理信息系统”将是建设项目工程行业的重大飞跃。工程造价管理系统构建与运用不仅会加快工程进度,也会使建设工程变得更加科学专业化。