Analysis of pre‐qualification criteria in contractor selection and their impacts on project success

While construction industry practices are reasonably well developed, construction projects still witness widespread failures of many contractors due to varied reasons such as financial problems, poor management, over‐commitment and or conflicts and disputes associated with construction activities. Pre‐qualification of contractors is a common practice across projects, yet the investigation on the ability of the selected contractors in successful delivery of projects is not widespread. In an attempt to understand these pre‐emptive qualification criteria and their links in contractors’ performance in projects, a total of 43 influencing technical attributes were identified through a systematic research approach. The relative significance and impacts of the attributes have been determined based on a structured questionnaire survey in selected construction projects. By performing the factor analysis, a total of seven factors significant to contractors’ performance were extracted, namely (1) soundness of business and workforce; (2) planning and control; (3) quality management; (4) past performance; (5) risk management; (6) organizational capability; and (7) commitment and dedication. Multiple linear regression models reveal that technical expertise, past success, time in business, work methods and working capital significantly impact on contractors’ performance across time, cost and quality success. With a clear understanding of a contractor’s performance, these findings could potentially contribute to development of a company’s procedures or enhance existing knowledge in relation to the pre‐qualification practices in contractor selection in projects.     

An innovative approach for generation of a time location plan in road construction projects

Existing linear scheduling methods for earthwork activities lack accurate scheduling locations in road construction projects. Project planners and construction managers largely depend on subjective decisions for the allocation of resources at correct locations. This has caused uncertainties in planning and scheduling, and consequently delays and cost overruns of projects. Accurate information of working locations is vital for efficient resource planning, scheduling and equipment mobilisation. A theoretical framework for a virtual construction prototype model is developed using the theory of location‐based planning and this is used as the basis of sensitivity analysis to identify critical factors affecting road construction. An arithmetic algorithm is developed by incorporating road design data, sectional quantities, variable productivity data, unit cost, site access points and haulage distance. The model generates a time location plan automatically with the aim to provide location‐based scheduling information of earthwork activities. Weekly progress profiles, terrain surfaces, cost profiles and S‐curve are the other outputs of the model. Data and information collected from the case studies are used to demonstrate functionalities of the model. Critical factors controlling the productivity of earthwork activities such as different types of equipment, soil characteristics and site access points were used to display the sensitivity effect by means of ‘what‐if scenarios’. The model is a valuable tool in analysing impacts of different factors associated with productivity data and resource planning from location aspects in the earthwork construction projects.     

Scenarios for applying RFID technology in construction project management

Radio Frequency Identification (RFID) technology has been widely applied in various areas such as retail, electronic transaction, logistic and supply chain management, scientific research, security, etc. It has brought about great benefits in these areas through improving real-time information visibility and traceability. However, a widespread application of RFID in the construction industry has not taken place. One possible reason is that construction practitioners may have not been fully informed of its potentials. This paper aims to investigate various scenarios that can illustrate the uses of RFID technology in construction project management. The research starts from a brief summary of recent developments of RFID technology in different industrial sectors including construction. 16 researchers were split into 3 groups to investigate how RFID can be used in the management of materials, men, and machinery (M³) for construction projects. Perspectives for future studies are proposed in order to fully realise the potentials. The research encourages a wider adoption of RFID technology in improving current PM practices. It also provides academia with a platform for further exploring the innovative uses of RFID technology in construction.     

R129住宅设计，德国

近年来，我们看到了材料、纳米技术以及传感技术的迅速发展。由此而导致的新发展和新方法正在大量地被应用于各行各业，比如汽车工程、飞机制造和太空技术；然而．房屋建筑在第三个千年开始的时候却仍然基本上使用一些几十年甚至几百年几乎没有改变的观念、技术和方法。为了在建筑业实现真正的发展，就必须置疑乃至重新定义其基本方法。     

A computer-based scoring method for measuring the environmental performance of construction activities

In line with the promotion of sustainable construction in the past decade, construction professionals have been contributing efforts in protecting the environment in implementing construction activities. Whilst such efforts will be contributed continuously, it is important that the level of the environmental performance in implementing construction activities can be properly measured and communicated to the public and project participants. This paper presents a scoring method for measuring the environmental performance committed by a contractor through calculating the contractor's environmental performance score (EPS). The level of EPS serves as a simple indicator for measuring and communicating the level of a contractor's environmental performance. The procedure for calculating EPS is formulated as an information technology (IT)-supported program. The program is designed not only to calculate EPS but also to allow for assisting contractors in diagnosing the causes of possible poor environmental performance. The diagnosis should enable the project parties involved to identify and adopt proper measures to improve environmental performance during implementing construction activities. A case study is formulated from a simulated environment for demonstrating the application of the EPS system.     

乡村振兴语境下陇中地区生土建筑的保护与更新策略 ——以甘肃省定西市通渭县为例

近年来快速城镇化过程中，西北乡 村建设与地域文化发展出现了种种问题。 在乡村振兴战略的背景下，如何在复杂的城 乡系统中找到合适的切入点打通症结，解决 文化、空间、生态多系统的“乡村病”值得深 思。本文针对乡村发展的现实问题，以当地 普遍建设的生土建筑为切入点，以生态宜居 建设与地域文化传承为目标，提出一系列相 关保护与更新策略，并以定西市通渭县为例 探讨。策略包括在提炼当地传统民居生态特 性的基础上，以工程技术手段优化生土建筑 的材料性能与建筑结构，扩大生态与社会可 持续效益；凝练生土建筑文化特性为设计建 设基础，以技术研究、绿色教育与艺术活动 激活文化内生动力，并完善法规规范支持地 域文化传承。实现将生土建筑发展成果有策 略地整合，为西北乡村振兴实践提供参考。     

Implementation of visualization as planning and scheduling tool in construction

During the last decade, extensive research efforts have been made on the development of four-dimensional (4D) models (space + time) which integrate computer graphics of three-dimensional geometrical models to scheduling data with a view to generating graphic visualization of construction processes for planning and decision making purposes. Nevertheless, these 4D applications to construction planning are often limited to the component level of a building. Their major drawback is the lack of pragmatic site management features, such as analysis of resource requirements for individual construction activity, generation of site facility layouts, quantification of construction materials and cost evaluation over a specified time period. The objective of this study on 4D graphics for construction planning and site utilization (acronym 4D-GCPSU) is mainly to furnish a solution to the aforementioned problem. In this paper, our works on 4D model in a broader site management context aiming to assist planners to deal with day to day activities are delineated. The prospective requirements for 4D application to support practical use on site management are also highlighted.     

超高性能混凝土在结构中的应用

超高性能混凝土(UHPC)具有超高的力学性能和超高的耐久性能,被认为过去三十年最优异的水泥基复合材料之一,能较好地适应当前土木工程结构大型化、复杂化的趋势,也能符合社会可持续发展对高性能材料发展要求。近年来,UHPC材料与结构已成为热点研究方向,相关专利与论文数量呈指数型增长,UHPC应用数量、范围与地区不断攀升,各类规范与标准也在不断地制定与修订之中。文章围绕超高性能混凝土的研究与工程运用现状,概括总结超高性能混凝土的性能特点,梳理超高性能混凝土在桥梁工程、建筑工程以及防护工程等领域的应用现状,结合笔者团队在超高性能混凝土应用方面的实践感悟,探讨超高性能混凝土规模化应用的关键环节,为超高性能混凝土材料今后进一步研发与应用提供参考。     

Emerging trends in expansive soil stabilisation: A review

Expansive soils are problematic due to the performances of their clay mineral constituent, which makes them exhibit the shrink-swell characteristics. The shrink-swell behaviours make expansive soils inappropriate for direct engineering application in their natural form. In an attempt to make them more feasible for construction purposes, numerous materials and techniques have been used to stabilise the soil. In this study, the additives and techniques applied for stabilising expansive soils will be focused on, with respect to their efficiency in improving the engineering properties of the soils. Then we discussed the microstructural interaction, chemical process, economic implication, nanotechnology application, as well as waste reuse and sustainability. Some issues regarding the effective application of the emerging trends in expansive soil stabilisation were presented with three categories, namely geoenvironmental, standardisation and optimisation issues. Techniques like predictive modelling and exploring methods such as reliability-based design optimisation, response surface methodology, dimensional analysis, and artificial intelligence technology were also proposed in order to ensure that expansive soil stabilisation is efficient.     

Segmentbrücke aus textilbewehrtem Beton: Konstruktion,Fertigung, numerische Berechnung

Segmental Textile Reinrorced Concrete Bridge Design, Manufacturing and Numerical Simulation Concrete provides a brought variety of construction and design possibilities. The low tensile capacity of concrete is taken by reinforcement of steel, short fibres or textile fabrics. Textile reinforced concrete (TRC) is a high performance composite in which technical textiles made of high performance fibers are embedded in a fine‐grained concrete matrix. Because of the corrosion resistance of the textile materials, thick concrete covers as known in ordinary reinforced concrete are no longer needed. Slender new concrete elements extend concrete application to completely new fields and gives architects and engineers more design possibilities. Design, reinforcement concept, production, approval tests, and numerical simulations considering uncertain data are demonstrated for the first bridge made of textile reinforced concrete. It is shown that application of this new, sophisticated composite material is already possible, although more research is needed.     

水泥基材料3D打印技术研究进展

3D打印技术是一种增材制造、快速成型技术,应用于建筑结构具有建造速度快、建造成本低、无模化施工和建筑垃圾少等优势.本文针对建筑结构的3D打印建造,介绍了三种适用的打印工艺,讨论了3D打印水泥基材料工作性能、力学性能与耐久性能的研究现状,对3D打印配筋增强构件的研究进展做了总结分析,对目前3D打印在建筑领域应用面临的问题...     

沥青路面就地冷再生技术应用研究

介绍了就地冷再生技术在某地区干线公路大修工程中的应用情况，研究了施工中的材料选择、机械配备、施工工艺，并对实施效果进行评价，提出推广应用的技术建议。     

建筑施工机器人研究进展

为了拓宽建筑机器人的研究思路和推广建筑机器人的应用,对国内外建筑施工机器人的研究进展进行了详细阐述。总结了建筑机器人的发展历程和系统组成,从主体结构施工、装修施工和其他新型施工机器人系统三方面对建筑施工机器人进行分类汇总,介绍了机器人的关键技术、性能优势和发展方向等内容。最后从研发设计、管理运维和人才培养等角度提出了建筑施工机器人的发展建议。结果表明:砌砖机器人产品存在依赖人工操作、使用非常规建材等问题,其机械臂的运动轨迹和任务规划是未来的研究热点; 基于激光标定技术的混凝土地面处理机器人智能化程度不高,需开发稳定高效的自主定位导航系统; 墙地面打磨机器人关键指标为施工精度和稳定性,可通过优化算法模型和引入高精度传感器进行提升; 室内喷涂机器人多为“6+3+1”自由度结构,对比手工喷涂具有明显的技术优势,但其自主化程度需进一步加强,而外墙喷涂机器人在稳定性、安全性和可靠性方面的性能要求更高,需提高作业覆盖率和实用性; 瓷砖铺贴机器人的发展离不开结构设计、瓷砖定位技术和铺贴轨迹规划等关键技术的研究,存在适用瓷砖尺寸单一和控制复杂等问题; 3D打印机器人通过优化结构设计提升作业灵活性,将朝着轻量化、智能化和低成本方向发展,而测量机器人主要利用三维激光扫描技术实现自动化测量,但面临着数据易丢失、人员活动范围受限和成本高等问题。     

就地冷再生技术在大修工程中的应用

介绍了就地冷再生技术在陕西咸阳地区干线公路大修工程中的应用情况,研究了施工中的材料选择、机械配备、施工工艺,并对实施效果进行评价,提出推广应用的技术建议。     

Review of recent developments in cement composites reinforced with fibers and nanomaterials

The quest for high-performance construction materials is led by the development and application of new reinforcement materials for cement composites. Concrete reinforcement with fibers has a long history. Nowadays, many new fibers associated with high performance and possessing eco-environmental characteristics, such as basalt fibers and plant fibers, have received much attention from researchers. In addition, nanomaterials are considered as a core material in the modification of cement composites, specifically in the enhancement of the strength and durability of composites. This paper provides an overview of the recent research progress on cement composites reinforced with fibers and nanomaterials. The influences of fibers and nanomaterials on the fresh and hardened properties of cement composites are summarized. Moreover, future trends in the application of these fibers or of nanomaterial-reinforced cement composites are proposed.     

泡沫混凝土的应用与质量控制

目前市场上的建筑保温材料,多为有机泡沫保温材料,如EPS泡沫板等.有机泡沫保温材料有保温效果好、重量轻、易施工等优点.但其防火性能差,施工时稍有不慎,就会发生重特大火灾事故.而泡沫混凝土,是一种新型的无机保温材料,其显著特点是不燃烧,成本低,寿命长,保温效果也较好,能满足建筑保温的要求.所以,泡沫混凝土很适合应用在建筑保温中.结果表明,在泡沫混凝土屋面保温施工中,严格执行施工工艺,采用标准的质量控制方法,就能达到合格的施工质量.实际应用表明:泡沫混凝土完全可以取代EPS板,用在建筑屋面保温中,可大大降低火灾损失.     

Deformability design of high‐performance concrete beams

The use of high‐performance materials (HPMs) such as high‐strength concrete (HSC) and high‐strength steel (HSS) is becoming more popular in the construction of beams and columns of tall buildings. These HPMs not only increase the stiffness and decrease the strength‐to‐weight ratio, but also provide a more sustainable construction method by minimising the construction materials needed. However, HSC and HSS are more brittle than normal‐strength concrete and steel, respectively. Therefore, it will adversely affect the deformability of concrete beams. To evaluate the pros and cons of adopting HPM in beam design, the author will investigate the flexural strength and deformability of concrete beams made of HPMs. The deformability in this study is expressed in normalised rotation capacity and investigated by a parametric study using nonlinear moment–curvature analysis taking into account the degree of reinforcement, confining pressure, concrete and steel yield strength. From the results, it is evident that the deformability of concrete beams increases as the degree of reinforcement decreases or confining pressure increases. However, the effects of concrete and steel yield strength depend on other factors. For practical design purpose, charts and formulas are produced for designing high‐performance concrete beams to meet with specified flexural strength and deformability requirement. Copyright © 2011 John Wiley & Sons, Ltd.     

Valuing a price cap contract for material procurement as a real option

This paper uses real option methodology to compare the cost of a long‐term contract with a price cap to that of spot purchases in construction material procurement. In construction, material procurements are usually short‐term, project‐based and subject to high price volatility. These characteristics and the competitive nature of the industry lower the profit margin of contractors. We have observed that contractors purchase a stable amount of commodity materials such as concrete, structural steel and lumber year after year. For contractors, the price cap reduces the price volatility of materials without their being obliged to purchase a certain quantity; for suppliers, the price‐cap contracts give them steady demand and a bigger market share. We evaluate this price‐cap contract as a real option and find the contractor's optimal ordering policy. When materials are not frequently traded, we model price processes by using related market information and then evaluate the idiosyncratic uncertainties in a risk‐neutral setting. Our methodology does not require market completeness and incorporates some of the results of the latest research in finance such as correlation pricing, option pricing and zero level pricing, as well as Monte Carlo simulation.     

钢纤维混凝土施工技术在路桥施工中应用

随着我国社会经济的不断发展进步,城市建设的进程也不断加快,与此同时公路和桥梁的建设步伐也得到了飞速的发展,这种现状也对建筑材料提出了更高的要求。近几年来,钢纤维混凝土在路桥施工中的应用也越来越广泛。钢纤维混凝土是一种新型优质水泥复合材料,这种材料与普通混凝土相比,具有以下几个方面的优点:施工简易方便、价格低廉、性能强等。本文主要从钢纤维混凝土的性能为出发点,进而研究钢纤维混凝土在路桥施工中的相关的技术应用。     

基于4D-BIM的施工资源动态管理与成本实时监控

针对建筑工程施工资源和成本管理的复杂性以及工程建造成本超过预算现象,通过建立4D施工资源信息模型和系统开发,实现了施工阶段对人力、材料和机械等资源的动态管理和工程成本的实时监控,为提高施工项目管理水平和成本控制能力探索了新途径和方法。