Large Engineering Construction Research Articles

Monitoring Algorithm of Stress Point of Concrete Penstock in Large Construction Engineering

With the rapid development of the national construction industry, cracks and other problems often appear in the concrete structure during the initial and subsequent construction. When these problems develop further, the structural safety of the entire building may be compromised. Therefore, it is necessary to analyze the causes of cracks and other problems in concrete buildings, and be able to monitor and analyze these problems in time, and then propose reasonable solutions. This is already a problem that the entire construction technicians urgently need to solve. This paper studies the algorithm for monitoring stress points of concrete penstocks in large construction projects. Firstly, it uses literature research to explain the form of stress nodes in large-scale construction projects and the deficiencies in the research on the stress nodes of concrete penstocks in large-scale construction projects. In the experiment, the existing 3 algorithms are used to detect the force points, and compare their detection degree and false alarm rate. The experimental results show that the detection effect of the KNN algorithm is obviously inferior to the other two algorithms with the same neighbor parameters. Its detection rate is only 91%, and the false alarm rate reaches 30%. The other two algorithms are equivalent. The detection effect of the KNN algorithm is obviously inferior to the other two algorithms, the detection rate is poor, the outlier force points that are obviously deviating from the whole around the dense force points are not recognized, and the data of many normal force points located at the edge of the sparse area Instead, it was recognized as abnormal. Among the three algorithms, the detection rate of the NLOF algorithm is better, reaching 99%, which is significantly higher than the other two algorithms.

DECISION-MAKING MODELLING IN A BUILDING ORGANIZATION MANAGING

Objectives. The aim of the work is to develop a situational decision-making model that provides effective management of the activities of large construction engineering organisations under the unstable conditions of the economic environment.Method. The research methods are based on the application of the methodological foundations of situational management and the principles of processing expert data using the mathematical apparatus of fuzzy sets.Results. A method for managing the activities of a construction engineering organisation under an unstable economic environment is proposed. Logical-transformational rules for deriving an information-analytical model of situational management and decision support under conditions of uncertainty are developed. The necessary conditions for the effective use of various logical-transformational inference rules and the need for an organisational management transition to multi-step situational management of the construction engineering organisation are defined.Conclusion. The results of the study allow the effective management of various types of activities of a large construction engineering organisation to be carried out in an unstable economic environment (i.e. under the unstable conditions of the contemporary market).

Social responsibility of engineering and construction enterprises under the “Belt and Road”

In order to enhance the value of large construction engineering enterprises in China and build a good corporate brand image in the “Belt and Road” initiative, China’s large-scale construction engineering enterprises must actively fulfill corporate social responsibility and do a good job in brand management. This paper takes listed companies in China’s engineering and construction industry from 2006 to 2017 as research samples to empirically test the impact of social responsibility disclosure on the performance of enterprise engineering projects. It is found that the engineering project performance of enterprises with social responsibility report disclosure is critically higher than that of enterprises without social responsibility report disclosure. Under different nature of enterprises, the disclosure of social responsibility report of non-state-owned construction engineering enterprises has a significantly greater impact on project performance than state-owned construction engineering enterprises. Further research also shows that the disclosure of social responsibility report has the most imperative impact on the performance of enterprise engineering projects in the current period. This paper argues that actively promoting engineering enterprises to fulfill their social responsibilities is conducive to promoting the development of large construction and engineering enterprises in the countries along the “Belt and Road” line.

Study on the Model of Financial Centralized Management in the Large-scale Construction Enterprises

Based on the research of financial centralized management and project financial centralized management, this paper comprehensively expounds the related theories of financial centralized management and analyzes the necessity of financial centralized management in large engineering construction enterprises. It also explores the financial centralized management mode of large engineering construction enterprises and puts forward some countermeasures.

Application of ultrasonic guided waves for non-destructive testing of large and complex geometry engineering structures

The wide group of large engineering constructions made from welded metal components and modern composite materials during daily exploitation under non-stationary loads, continuous influence of vibrations and complicated environmental conditions have demand of periodical tests in order to avoid appearance and evolution of the defects. All of them have one common feature – large areas to be tested and the complex geometry. The objective is to improve air-coupled and contact type testing techniques for excitation and reception of appropriate modes of ultrasonic guided waves in large and complex structures. Also, to develop inspection techniques which enable to detect required types of internal defects. The air-coupled and contact ultrasonic techniques for investigation of large and complex geometry objects, such as composites for aerospace applications and petroleum tanks, have been developed. The investigation of propagation effects of ultrasonic guided (Lamb) waves in the plates of the tank floor has indicated relation between reconstructed properties of guided waves and expected presence of corrosion deposits.

Piezomagnetic In-situ Stress Monitoring and its Application in the Longmenshan Fault Zone

The relative change of in-situ stress is an inevitable outcome of differential movement among the crust plates. Conversely, changes of in-situ stress can also lead to deformation and instability of crustal rock mass, trigger activity of faults, and induce earthquakes. Hence, monitoring real-time change of in-situ stress is of great significance. Piezomagnetic in-situ stress monitoring has good and longtime applications in large engineering constructions and geoscience study fields in China. In this paper, the new piezomagnetic in-situ stress monitoring system is introduced and it not only has overall improvements in measuring cell's structure and property, stressing and orienting way, but also enhances integration and intelligence of control and data transmission system, in general, which greatly promotes installing efficiency of measuring probe and quality of monitoring data. This paper also discusses the responses of new piezomagnetic system in large earthquake events of in-situ stress monitoring station at Qiaoqi of Baoxing and Wenxian of Gansu. The monitoring data reflect adjustments and changes of tectonic stress field at the southwestern segment of and the northern area near the Longmenshan fault zone, which shows that the new system has a good performance and application prospect in the geoscience field. Data of the Qiaoqi stress-monitoring station manifest that the Lushan Earthquake did not release stress of the southwestern segment of the Longmenshan fault zone adequately and there still probably exists seismic risk in this region in the future. Combined with absolute in-situ stress measurement, carrying out long-term in-situ stress monitoring in typical tectonic position of important regions is of great importance for researchers to assess and study regional crust stability.

NUMERICAL MODELING OF VERTICAL WELLS IN UNSTEADY GROUNDWATER FLOW CONDITIONS

Abstract This article presents the results of numerical calculations of drainage of a large engineering construction - “Afrykarium” in Wrocław ZOO, Poland, based on a 2D numerical model for seepage flow. In the numerical simulations the real (natural) hydrogeological conditions, water-courses, surface reservoirs and time dependent seepage flow (during drainage) are taken into account. The aim of numerical calculations was to determine quantities (draining time, number of wells, spacing and arrangement of wells, flows for every well, and hydraulic head map) necessary to design an effective drainage system of construction site. The mathematical model adopted to illustrate and predict groundwater depression during pumping was the Boussinesq equation for unsteady 2D flow.

Study on Scenario Analysis Method Based Safety Pre-Warming of Large Construction Engineering

For large construction engineering, to perform safety pre-warming more efficiently, scenario analysis method (SAM) is studied for safety pre-warming of large construction engineering (SPLCE). Implement flow framework of SAM is established, the key cycles of SAM are discussed. To validate the validity of SAM for SPLCE, some practical instances of SPLCE are abstracted so as to generated application and testing sample. Comparing with whole index evaluating method (WIEM), under the condition of considering only limited key driven forces and some normal indexes, the result by SAM are almost the same with that by WIEM. SAM improves the efficiency of SPLCE, and it is fit for solving complex predicting, analyzing and evaluating problems such as SPLCE.

Contested overruns and performance of offshore wind power plants

Offshore wind power plants are expected to expand rapidly in the coming years. These large engineering construction projects are important for climate change mitigation. The paper contributes to socio-technical understanding of engineering construction. Cost, time, delays and performance results of selected British plants are investigated, with a focus on strategic misrepresentation. This megaproject concept is combined with a socio-technical content analysis of offshore wind farms and provides a technologically precise and contemporary conceptualization in comparison with complex engineering and megaproject approaches. Based on publicly available data, budget and time overruns and underperformance are demonstrated. Budget overruns range from 0% to 65%; time overruns from 9% to 100%, Operational performance indicators reveal plants far below and just below estimations. These are all indications of strategic misrepresentation, but according to project players, the delays originate from weather, product technology, site features and processes. The findings thus indicate a latent controversy regarding reasons for overruns. A socio-technical variant of reference class forecasting (RCF) is developed to explore whether RCF could improve the estimates. Socio-technical RCF is developed for 10 plants that share foundation, national and geotechnical conditions. This provides an illustrative example of a proposed uplift for London Array. Such an RCF should be orchestrated with more governance mechanisms in order to improve future investments in engineering construction, including offshore plants.

Planning and design models for construction industry: A critical survey

Abstract Large construction engineering projects involve various types of resources, such as labor, equipment and materials, which require planning and design for efficient operations and economic benefits. Any component of these types of resources demand initial investment, costs, logistics operations, scheduling and many other associated aspects of planning, design and operations of the projects. This paper studies different planning and design models developed for various aspects of construction industry. Most of these studies incorporated mathematical models and simulation based on some real life data. Applications of basic principles of operations research and industrial engineering relating to logistics and procurement have been incorporated for an effective planning and operations of these projects. A critical survey of different important aspects of planning and designing used in construction operations has been pursued here. The general behaviors of design variables and evaluative measures have been presented and discussed in general fashion.

Excavation unloading destruction phenomena in rock dam foundations

Excavation unloading destruction (EUD) is a common phenomenon in the large-scale construction sites in Southwest China, where intense horizontal tectonic stresses are present in the rock mass. The paper discusses the Xiaowan hydropower dam where stresses of 23–35 MPa were measured in the strata in the valley sides and 44–57 MPa in the floor of the valley. It describes the characteristics of EUD, discussing the laminar, arched and imbricate fractures which occurred when the near surface strata were excavated for the dam construction. The EUD fractures were largely restricted to the upper 6 m below the excavation and were particularly pronounced in the top 2 m. It is concluded that the typical Mohr Coulomb formula is not applicable where a rock mass near its critical stress is rapidly unloaded. A better understanding of EUD is important for the prediction of rock bursts etc. and hence safety in large engineering constructions in highly stressed strata.

Review and implementation of performance management models in construction engineering organizations

Performance management is a key issue in the construction industry as a result of complex internal and external factors. Large construction organizations are implementing performance management models to improve business processes, products and management of people to facilitate continuous improvement. This study investigates the implementation of performance management models in large construction engineering organizations. First, a brief review of the drive for performance improvement and the strategic considerations for the adoption of performance management models is carried out with specific reference to the Balanced Scorecard and the EFQM Excellence Model. Second, using case studies of large construction engineering organizations, the findings from the implementation of performance management models are analysed and discussed. It is shown that whilst progress has been made in the implementation of performance management models in large construction organizations, significant challenges remained at the planning, deployment and assessment and review stages. This includes the motivation for performance management, leadership and resources, communication mechanisms, measurement and data collection techniques and the role of knowledge management. Performance management models provide a basis to develop strategy for sustaining longterm business objectives, and more construction organizations will adopt such innovative tools to facilitate continuous improvement, as the business benefits become clear.

Information asymmetries and technological innovation in large engineering construction projects

AbstractResearch on technological innovation shows that information asymmetries between suppliers and buyers constitute a major barrier to the successful introduction of new products. Most of this research, however, puts the burden of overcoming these asymmetries on producers of new products. In the case of large engineering construction projects innovation is often the result of joint problem solving by owners, prime contractors, consultants, and equipment suppliers. In this paper we examine the relationship between innovativeness of large engineering construction projects and internal owner capabilities, degree of control over project, and dependence on external organizations, We use data on power plant construction projects to test hypotheses derived from agency and organization theories of innovation. Our results indicate that organization theories of innovation are on the whole better predictors of the impact on innovativeness of owner's capabilities and relationship to external organizations.

Implications of terrain movements in Egypt

The purpose of this paper is to study the causes of localized terrain movements in Egypt. The motivation behind this research has been the vast progress in constructing huge engineering structures (dams, bridge,, tall buildings, etc.) as well as extending the urban activities in many new cities. These must be properly studied to ensure their safety versus their cost and other economic factors. In addition, the recent tendency is towards building nuclear power stations whose locations must be carefully investigated against the hazard and danger of inevitable atomic leakage, especially in the case of seismically active regions. Also the discovery of new oil wells and mines and the effects of future depletion require considerable attention from qualified investigators. The relative tectonic movements of North Africa and Southern Europe, the seismic activities around the Alexandria region, the presence of faults related to the region of the High Dam and its reservoir in Aswan, the erosion of the banks of the River Nile and its islands as well as coastal lines along the Mediterranean and the Red Sea, and the deformation and damage to large buildings in the Cairo area are examined here as a few examples of the implications of the earth's deformations within Egyptian territory. Strong recommendations are made concerning the necessity of studying and monitoring the terrain movements in the areas where new cities, large engineering constructions and power plants are planned to be erected.

New Laser Applications in Geodetic and Engineering Surveys

Large engineering constructions and first-order geodetic control nets often require a relative accuracy of 10(-6)or better in positioning of survey points. A team from the University of New Brunswick has developed new instruments for precision alignment surveys and for engineering and geodetic leveling which satisfy the demands for accuracy. Prototypes of integrating centering detectors have been designed and constructed which allow alignment of laser beams with an accuracy of 0.2 sec of arc in a turbulent atmosphere over distances of a few kilometers. Two types of laser plummets have been developed to set a laser beam in a vertical direction with an accuracy of 0.5 sec of arc or better. A He-Ne laser has been adapted to a conventional self-aligning level giving a standard error of 0.7 mm/km in determination of a difference in elevation. A new type of laser level has been constructed which gives new possibilities for precision leveling.

New laser applications in geodetic and engineering surveys

Abstract : Large engineering constructions and first-order geodetic control nets often require a relative accuracy of 10 to the minus 6th power or better in positioning of survey points. A team from the University of New Brunswick has developed new instruments for precision alignment surveys and for engineering and geodetic leveling which satisfy the demands for accuracy. Prototypes of integrating centering detectors have been designed and constructed which allow alignment of laser beams with an accuracy of 0.2 sec of arc in a turbulent atmosphere over distances of a few kilometers. Two types of laser plummets have been developed to set a laser beam in a vertical direction with an accuracy of 0.5 sec of arc or better. A He-Ne laser has been adapted to a conventional self-aligning level giving a standard error of 0.7 mm/km in determination of a difference in elevation. A new type of laser level has been constructed which gives new possibilities for precision leveling. (Author)