开孔板连接件相对滑移机理试验研究

为研究组合结构桥梁中开孔板连接件的相对滑移机理,以开孔板厚度、孔中钢筋直径、开孔板孔径为变化参数,进行了21个开孔板连接件抗剪性能模型试验。通过理论分析与试验结果比较,揭示了开孔板连接件相对滑移量主要由孔中钢筋剪切变形量、孔中混凝土压缩变形量和剪切变形量三部分组成,以及抗剪承载力对应相对滑移量随板厚增加而减小,随孔径、孔中钢筋直径增加而增大的滑移机理。     

Development of a shrouded wind turbine with a flanged diffuser

We have developed a wind turbine system that consists of a diffuser shroud with a broad-ring flange at the exit periphery and a wind turbine inside it. The flanged-diffuser shroud plays a role of a device for collecting and accelerating the approaching wind. Emphasis is placed on positioning the flange at the exit of a diffuser shroud. Namely, the flange generates a low-pressure region in the exit neighborhood of the diffuser by vortex formation and draws more mass flow to the wind turbine inside the diffuser shroud. To obtain a higher power output of the shrouded wind turbine, we have examined the optimal form of the flanged diffuser, such as the diffuser open angle, flange height, hub ratio, centerbody length, inlet shroud shape and so on. As a result, a shrouded wind turbine equipped with a flanged diffuser has been developed, and demonstrated power augmentation for a given turbine diameter and wind speed by a factor of about 4-5 compared to a standard (bare) wind turbine. In a field experiment using a prototype wind turbine with a flanged diffuser shroud, the output performance was as expected and equalled that of the wind tunnel experiment.     

Time to build options in construction processes

Time to build is a very important factor in a real estate development venture. Delay in completion of a project not only affects the financing costs and the rental revenue but also it may, on a more strategic note, determine the success or failure of a project. A time to build option model consisting of a stochastic rate of completion and a stochastic net project payoff is applied to the sequential construction process of a large scale construction project. The results of the sensitivity analysis show that the optimal payoff value, that triggers the exercise of the option to invest at a maximum rate, increases positively with the increases in cash flow volatility, input cost uncertainty, excess asset return per unit risk and maximum rate of investment. However, it has a negative relationship with the rental yield. In a case study involving a commercial project, the premium for hedging the payoff risks by pre-leasing a project was estimated at 11.29%, whereas the additional cost incurred for shielding a project against input cost risks in a design and build contract was estimated at 7.80%, where each is given as a percentage of the total construction costs.     

Robot-based construction automation: An application to steel beam assembly (Part I)

The construction industry has not traditionally been a favorable field for the application of robotic technologies. However, various motivations such as the shrinking labor population, the aging of skilled workers, and the safety issue of ironworkers have promoted the development of robotic construction systems. In this research, one of those trials, a project entitled “Robot-based construction automation system for high-rise building” is presented. Among diverse construction works, this project focused on a robotic automation of the steel beam assembly. The project is a cooperative effort between a robot research group and a construction automation group in South Korea. The main objective of this paper is to an introduction for the development of a robotic beam assembly system administered by the robot research group. The robotic beam assembly system consists of a robotic bolting device that performs the main function for the beam assembly work and a robotic transport mechanism that transports the robotic bolting device to target bolting positions around a building under construction. This paper presents the specific functions, structures, and mechanisms of the robotic bolting device and accounts for the application of the visual servo control technique to a bolting control system which is a software component. The robotic transport mechanism part is discussed in a companion paper [14]. The real prototype of the proposed system was manufactured and intensive field tests were conducted in a test bed. Moreover, this system was applied to a section of a real building, the Robot Convergence Building of Korea University, South Korea, which has one story below and seven above the ground, and obtained a feasibility of an application of the robotic beam assembly system to actual construction sites. The suggested system is expected to be a promising alternative to ironworkers in the steel beam assembly in terms of safety and time-efficiency.     

Motion Planning for an Autonomous Compactor in a Waste Landfill Site

Abstract: This paper describes the algorithms and detailed path-planning methodologies developed to enable autonomous spreading and compaction processes in a waste landfilling operation. A given landfill site is spatially decomposed into cells using a recursive spatial decomposition technique. The cell size is determined using a probabilistic model for waste generation. Variation in the amount of waste generated on a given day is handled by a further spatial decomposition of a cell into monominoes. The recursive spatial decomposition processes of a landfill site into cells and each cell into monominoes are accomplished by employing a variant of quadtree data structure. A three-dimensional path plan for an autonomous compactor that considers a variable working gradient in the range of 3:1 to 2:1 is generated for a pair of monominoes. Automatic location of the working place for a compactor is accomplished by a recursive traversal of the quadtree structure. The algorithms have been implemented using a computer-graphic functional interface standard with C-program binding.     

A quantitative approach to the assessment of the environmental impact of building materials

The materials from which a building is constructed make a significant contribution to its overall impact on the environment. This impact is felt in a number of ways; locally, through the effects of activities such as quarrying; globally, as a result of carbon dioxide released by using energy used to manufacture the materials; and internally, in the effects on the health of the occupants of the building.

Some of these effects are easier to measure than others, and comparisons between the seriousness of the different effects are difficult to make. It therefore seems unreasonable to attempt to devise a single figure of merit for the overall environmental impact of a building; what is needed is a profile which gathers together a range of indicators, but allows them to remain separate. This article describes the development of such an environmental profile which can be used as a design aid, and illustrates its use with a case study of a typical British house.     

Theoretical aspects of the design of a passive radon dosemeter

Some mathematical aspects of the development and design of a passive radon dosemeter are considered. In particular, a mathematical model is presented that is concerned with the gaseous diffusion of radon into a confined region bounded by a plastic material of known diffusion coefficient. The relationship between the time-integrated radon concentrations, inside and outside a sealed plastic container are derived. Estimates of the exposure of people to radon can be made using the time integrated radon concentration inside a calibrated container containing a CR-39 etched-track device. As a consequence of the analysis, it is possible to design a passive radon dosemeter that will be accurate, resistant to moisture and whose response will be independent of rapid variations in radon concentration. The possibility of using a container of this type for the measurement of diffusion coefficients is discussed.     

帕拉莫斯贝尔略克酿酒厂,赫罗纳,西班牙

在独特的环境中建造一座私人酿酒厂,要兼备制造与品尝的功能。在山脚下,山谷的起始,一处受到庇护的地方,这里是项目的发源地。在这样的环境中,不同属性的建筑出现了,包括山脚下的一个小礼拜堂。在贯穿所有组成部分的路径上,出现了一段有屋顶且下沉的路段。它被埋在葡萄树下,好似一个坟墓,这就是酿造厂的生产空间。它不是一个独立的空间,而是一条步行道,由此可以发现不同的空间,而起伏的路径强调出其自身的维度。     

Development of a smart city planning support tool using the cooperative method

A reduction of environmental burdens is currently required. In particular, proposing a new approach for the construction of a smart city using renewable energy is important. The technological development of a smart city is founded building equipment and infrastructure. However, planning methods and their techniques using the collaboration approach with residents are only just developing. This study aimed to develop a support tool for the construction of a smart city using renewable energy while facilitating consensus-building efforts among residents using the method for a cooperative housing development. We organized the supporting methods for the construction of residential area using the cooperative method. Then, we developed supporting tools that interface the computer with these methods. We examined the support techniques for the construction of a residential area using renewable energy technology by analyzing Japanese cases of a smart city. Moreover, we developed a support tool for the construction of a smart city on a trial basis. We integrated the smart city construction tools and the cooperative housing construction support tool. This tool has a 3D modeling system that helps residents to easily understand the space image as a result of the examination. We also developed a professional supporting tool that residents can consider for cost-effectiveness in renewable energy and its environmental load reduction rate for the planning of a smart city.     

Management of bridges with shallow foundations exposed to local scour

Abstract

The Serbian road network includes a large portion of bridges with shallow foundations vulnerable to local scour as tragically demonstrated during the extreme flooding in May 2014. Currently, the bridge management procedures in Serbia and worldwide do not comprehensively account for a risk of bridge failure due to flooding and fail to provide sufficient information for the decision-making. Thus, a novel methodology for quantitative vulnerability assessment is suggested as a tool to identify the most vulnerable bridges in a network. Herein, the essential task is evaluation of the conditional probability of a bridge failure due to local scour in a flooding event of a certain magnitude. To apply this approach on a network level, there is a dire need to establish precise practice-ready guidelines on an optimal set of information to be used and/or collected in situ, which is discussed on an example of the Serbian bridge database. The vulnerability of a bridge to local scour may be used as a comprehensive indicator of a bridge performance in a flooding event. For a network level, the vulnerability maps with respect to flooding of different magnitudes will give road operators crucial information to apply adequate quality control plans to vulnerable bridges.