Initial Stage Of Construction Research Articles

Risk Management of Bored Piling Construction on Sandy Soils with Real-Time Cost Control

In a global society, in which geotechnical projects are increasingly designed in a country other than the one where construction takes place, geotechnical risk management must be extended to cover infrastructure works, which are smaller than dams and tunnels, for example, since there is a significant impact on works budget imponderables. Therefore, a risk management methodology based on the likelihood of the occurrence of certain events and their economic consequences is proposed, which is applicable to bored piles (Kelly drilled) in coarse soils, easy to use, and simple to implement since the initial stage of construction. Of 12 case studies of construction works involving bored piles (Kelly drilled) carried out in Luanda (Angola), two selected examples involving the proposed risk methodology on sandy soil layers with interbedded clays are discussed. Subsequently, whether the overall foundation contract budget is affected by assessed risk is determined, and what influence it has on the budget in the light of mitigating factors and associated real costs. This method intended to encourage the adaptation of sustainable risk management in bored piles construction by the site project managers, involving risk analysis concurrently with budgetary review. Though the level of assessed technical risk may be acceptable, overall costs associated with the contract in question may not be acceptable.

Обґрунтування системи геодезичного моніторингу із використанням рейки змінної довжини

The purpose of improvement of the accepted geodetic decisions concerning the program of geodetic monitoring of highrise buildings of a difficult design taking into account conditions of the increased danger of a construction site Method. Execution of geodetic observations of subsidence of a multi-storey building under the condition of joint use of invar rail and rail of variable length according to the leveling program of the first class. Comparative observations of the displacement of the structure using a high-precision optical theodolite and an electronic total station. Results. Improved methods and geodetic accessories for determining the plan-height deformations of buildings erected in difficult geological conditions. . Scientific novelty. Search and collection of initial information, analysis of normative documentation on the organization of geodetic monitoring of deformation of engineering structures are carried out. Methods for determining the deformations of engineering structures are analyzed. The advantages of class I geodetic observations with the help of accurate optical geodetic instruments over other methods are proved. Comparative studies of the accuracy of a modern electronic total station and a high-precision optical theodolite were performed in the field. The planned and height dynamics of deformation processes of building structures during the construction period and at the initial stage of operation are determined. A comparative analysis of the results of determining the deposition of the pile field by methods of loading piles with hydraulic jacks and the load from the actual mass of the aboveground part of the house. It is established that the largest deformations of the structure occur at the initial stage of construction and gradually fade after its completion. The calculation of the accuracy of geodetic works with the joint use of traditional invar rails and rails of new design. Practical value. The organization and conduct of geodetic works to monitor the deformation processes of multi-storey buildings on the developed technology of precision leveling contributes to the timely establishment of maximum allowable values of deformation, risk prevention, to preserve the safety of residential complexes under difficult geological conditions. A new design of the leveling rail and a leveling technique with the simultaneous use of a standard invar rail and developed by the authors have been developed. Improved method of linear-angular measurements for monitoring the planned deformations of buildings.

Analysis of Quality Control Methods and Equipment for Monolithic Reinforced-Concrete Structures

This article deals with the study of methods and equipment for nondestructive testing of concrete strength and describes the characteristics of ultrasonic devices used for control and determination of concrete mix integrity. Quality control for monolithic reinforced-concrete structures covers a range of issues associated with testing the material strength of structures and determining, if necessary, armoring parameters of reinforced-concrete structures, testing concrete cubes, as well as analyzing design and as-built documentation, drawing up control section diagrams, etc. The article contains a description of quality control equipment and methods for concrete and reinforced-concrete structures and an analysis of the main quality control methods and means. Generalization and systematization of available data lead to a conclusion on the need for development of technical solutions that would prevent potential defects at the initial stage of construction and installations works.

Optimization of soil movements when planning terrain

Earth work is considered when planning the terrain at the initial stage of construction. Instead of a manual method for calculating the volume of soil transportation, it is proposed to switch to the use of linear programming methods and computer solutions in the environment of the computing complex Matlab. The problem is stated, algorithms and a computer program are developed. The optimal plan for transporting soil masses from dredges to embankments was found for a specific task.

AERATED CONCRETE AS AN ENERGY-EFFICIENT MATERIAL FOR WALLS

Abstract. In the context of tightening the thermo-technical requirements for building envelopes, the benefits and advantages of energy-efficient wall material of autoclaved aerated concrete and aerated concrete products are shown. Domestic and foreign researches in the field of rational use of autoclaved aerated concrete for external walls in modern construction of energy-efficient buildings and optimization of structural solutions of aerated concrete walls are generalized. The most important thermos-physical characteristic for assessing the thermal resistance of external walls made of aerated concrete is the value of the thermal conductivity coefficient. The moisture content of aerated concrete has a significant effect on thermal conductivity, the release moisture is several times higher than the calculated moisture content stipulated by the standards for construction heat engineering and operating conditions. In the initial stages of construction, the moisture content of aerated concrete exceeds the moisture content established in the normative documentation by operating conditions, which requires recalculation of the thermal resistance of the walls of buildings taking into account the real moisture content of aerated concrete used during construction. A detailed explanation of the dependence of the heat flow through the enclosing structure on its resistance to heat transfer, established in the form of a hyperbola, is given, and the dependence of the difference in thermal conductivity on the moisture content of aerated concrete blocks is presented. When analyzing the effect of moisture on the thermal conductivity of aerated concrete, was used the characteristic deviation ± Δλ of thermal conductivity of aerated concrete in a wet state from the thermal conductivity of concrete in a dry state was used. Based on the results of the experiment carried out at OSACEA, the main conclusions and recommendations for determining the coefficient of thermal conductivity of aerated concrete in dry and wet conditions are given. Some aspects of energy saving in construction practice are presented, based on materials prepared by Doctor of Technical Sciences, prof. Gagarin V.G. The need to improve specific energy-saving measures is shown, which should be economically viable and not reduce the durability of construction objects. Generalized conclusions and recommendations are given.

Influencing factors and stage characteristics of intelligent construction of rural tourism in Fujian

<p>With the help of qualitative analysis software Nvivo11, this paper makes a rooted analysis on the field text data of six rural tourism spots in Fujian Province. It shows that the influencing factors of the intelligent construction of rural tourism mainly including human capital, performance expectation, effort expectation, social impact, market demand and capital conditions. In the initial construction stage of rural tourism, the influence of capital conditions and human capital is stronger; in its development and construction stage, the impact of performance expectation is the most critical, followed by effort expectation and capital conditions; In its relatively mature stage, performance expectation and effort expectation are the dominant factors, followed by social influence. To promote the intelligent construction of rural tourism, effective measures should be taken according to the key factors in different development stages. It should be guided by the actual needs of tourists, pay attention to the fit with the positioning of rural tourism destination and target market, and avoid being intelligent for the sake of intelligence.</p>

SELECTION AN OPTIMAL NUMBER OF VARIABLES IN REGRESSION MODELS USING ADJUSTED COEFFICIENT OF DETERMINATION AS A MIXED INTEGER LINEAR PROGRAMMING PROBLEM

When constructing a regression model, the primary problem faced by the researcher is that it is not clear what the equation of connection between the explained and explanatory variables should be. This initial stage of construction the selection of the model structural specification is called. When choosing a regression specification in parallel, the question arises of which explanatory variables should be included in the equation. This is the problem of variables selection in regression models. Its essence is to single out from the set of “candidates” for inclusion a subset of the most informative of them based on some quality criterion. The article is devoted to the problem of variables selection in regression models estimated using the ordinary least squares. The previously proposed approach to selection a given number of variables based on mixed 0–1 linear programming is considered. The unknown parameters in this problem are the beta coefficients of standardized regression and Boolean variables that are responsible for the occurrence of factors in the model. The optimal values ​​of unknown parameters are found on the basis of maximizing the value of the coefficient of determination of regression. Unfortunately, to solve the problem under consideration, it is required to manually set the number of selected factors, which is often impossible to determine in advance. Therefore, the goal was to formalize the problem so that as a result of its solution the optimal number of selected regressors was also determined. For this purpose, the adjusted determination coefficient, depending on the number of model factors, was used as the objective function. As a result, the problem of mixed integer linear programming was formulated. The unknown parameters in it are still beta coefficients and Boolean variables, as well as an integer variable – the number of regressors. Based on data on prices and characteristics of sedans and hatchbacks of the American automobile industry, a computational experiment was carried out confirming the correctness of the developed mathematical apparatus. The problem formalized in this work in the form of a mixed integer linear programming looks more preferable from a computational point of view than the same problem formalized in modern scientific literature as a mixed quadratic linear programming.

M.G. Arnold, the first architectural engineer of Tomsk State University

The paper considers the architectural and construction activities of M.G. Arnold, the first architectural engineer of Tomsk State University. According to scientific publications, his activity remains in the background and even receives a negative assessment in memoirs of contemporaries. In addition to traditional printed sources, this paper includes information from the hand-written journal of the Committee for Construction of Siberian University Buildings in Tomsk. These data allow to show the activity of M.G. Arnold in detail and identify his contribution to the initial stage of construction of Tomsk State University in 1880. The location of the hall for laying of the foundation stone is graphically reconstructed, including the memorial plaque.

Research on deformation control and prevention measures of pile anchor support system in foundation pit

With the rapid development of urban modernization, the pile anchor support system has been widely used in the deep foundation pit project. Because the deformation of the pile anchor support system directly affects the overall stability of the foundation pit and brings serious potential safety accidents to the construction of the deep foundation pit, avoiding the deformation of the pile anchor support system can effectively prevent the occurrence of the construction safety accidents of the deep foundation pit. Based on many years of construction experience, the deformation rule of pile anchor support system of deep foundation pit is taken as the research object. This paper starts from the scheme design of pile anchor support system and the monitoring data of the foundation pit, and combines with the actual deformation of the pile anchor support system in the construction site, summarizes the causes and prevention measures of the deformation of the pile anchor support system in the construction stage. The research results show that in the initial stage of construction, the top of the pile anchor support system inclines forward to the pit and gradually changes into a bow shape. This kind of deformation is related to the increase of excavation depth and the erosion of active soil pressure area by surface water. In the later stage of construction, the deformation of the top of the foundation pit converges and the bottom of the pile anchor support system protrudes into the pit, which is related to the erosion of the passive soil pressure area by rainwater and the embedded depth of the pile foundation.

Modified Marshall Test assessment for emulsified asphalt cold mixes

Asphalt cold mixes are attractive to transportation agencies for their simplicity in set-up, less energy requirement, ease of application, and environmentally friendliness, though it suffers setbacks in terms of lack of a universally acceptable mix campaign, high water susceptibility, and low mechanical strength at initial stages of construction. However, they are widely used for rehabilitation and maintenance works, and to a lesser extent construction in low-trafficked roads. Notable among the cold mixtures is polymer modified emulsified asphalt micro-surfacing, which is used as a thin non-structural layer for the restoration of skid resistance and waterproofing. Marshall test is used to assess its performance similar to a structural wearing course layer. This study assessed the mechanical performance of cold mixtures by a modified Marshall mix employing a low viscosity cationic quick set emulsion (CQS-1h) and a cationic rapid set emulsion (RS-1k) and a 60/70 penetration grade binder. Rheological criteria assessment was conducted on both emulsions including particle charge, residue by evaporation, settlement and storage stability, solubility in inorganic solvent sieve test, and Saybolt Furol viscosity, while the residue from evaporation was tested for microstructural and mechanical performance, 65% and 63% residue by evaporation, dissolved in trichloroethylene at 95% and 100% for CQS-1h and RS-1k respectively.

Durability rehabilitation and promotion of reinforced concrete structures in tidal and splash range of deteriorated wharfs in marine environment

Corrosion deterioration of reinforced concrete structures in tidal and splash range has always been an urgent concern of scientific researchers and wharf managers, especially for that serving for more than 20 years in marine environment. Through on-site detection and chemical analysis, it has been found that reinforced structures in tidal and splash range of a passenger terminal in Zhoushan city suffer severe corrosion destructions such as rust expansion of steel bars, concrete cracking and spalling due to technical conditions at the initial stage of construction and insufficient awareness of durability. Meanwhile, chloride content near the surface of steel bars in concrete exceeds the critical corrosion value. In order to rehabilitate and improve the durability of reinforced concrete structures in tidal and splash range of this wharf, a combined programme of partial consolidation and electrochemical desalination is proposed and applied, which shows good performances and ensures the service life of the structure as long as possible.

Investigation and Analysis of Wall Cracks in Cement Stabilized Rammed Earth Technology

Cement stabilized rammed earth (CSRE) is one of the developed and affordable housing technologies, adopted in many countries, which has been used in Sri Lanka since 2004 for building single and two-floor houses. Steel slip-form and timber formwork have been used for casting walls. Information collected on wall cracks under these two methods is analyzed to justify the reasons for these cracks. Data collected at the initial stage of construction and its serviceability period of 12 years is considered under this study. Most of the walls have been in satisfactory condition, but few had to be repaired. CSRE wall tends to crack similar to other masonry technology due to faulty construction and environmental changes. Major issues are the cracks due to shrinkage of CSRE material which appeared after one year period of construction. Detailing the construction with the provision of shrinkage cracks is required to mitigate the vertical cracks on CSRE walls.

Study on the influence factors of urban subway project delay in the initial construction stage

The factors that lead to the delay of construction project of urban subway construction are complicated. In this paper, the influence factors of urban subway project delay in the initial construction stage was studied and the urban subway project delay evaluation system consisting of 37 key indicators was established by combining with the first-hand data obtained from the subway construction management and related literature. The weight of each indicator in the evaluation system was calculated by using the structural equation model to analyze the data of the questionnaire. The core influencing factors are analyzed and the corresponding suggestions were put forward to minimize the occurrence of delays in subway construction.

Architecture Characteristics of Burrow System of Plateau Pika, Ochotona curzoniae

Burrows serve many functions for animals by providing a place for rearing young, sleeping, hibernation, food storage, protection from predators and extreme environment, and the function of burrows varies with the degree of burrow complexity. We studied the burrow architecture (length, internal dimensions, fractal dimension of tunnel systems, number of nesting chambers and surface holes) by excavating the tunnels of 24 burrow systems of the plateau pika (Ochotona curzoniae). Pikas have two types of burrow systems, namely temporary and permanent burrows. The number of surface holes and length of tunnels were significantly different between the temporary and permanent burrows. Tunnel width and tunnel height were not significantly different between the temporary and permanent burrows. The permanent burrow had a nesting chamber but temporary did not have any. No hoarding chamber was found in either the permanent or the temporary burrow. The temporary burrow was used to avoid predators in emergency situations, and probably was the initial stage of construction of more complex burrows of some dispersing pikas. Permanent burrows were used for avoiding predators, resting and rearing offsprings.

Linking Structural Equation Modelling with Bayesian Network and Coastal Phytoplankton Dynamics in Bohai Bay

Bayesian networks (BN) have many advantages over other methods in ecological modelling and have become an increasingly popular modelling tool. However, BN are flawed in regard to building models based on inadequate existing knowledge. To overcome this limitation, we propose a new method that links BN with structural equation modelling (SEM). In this method, SEM is used to improve the model structure for BN. This method was used to simulate coastal phytoplankton dynamics in Bohai Bay. We demonstrate that this hybrid approach minimizes the need for expert elicitation, generates more reasonable structures for BN models and increases the BN model’s accuracy and reliability. These results suggest that the inclusion of SEM for testing and verifying the theoretical structure during the initial construction stage improves the effectiveness of BN models, especially for complex eco-environment systems. The results also demonstrate that in Bohai Bay, while phytoplankton biomass has the greatest influence on phytoplankton dynamics, the impact of nutrients on phytoplankton dynamics is larger than the influence of the physical environment in summer. Furthermore, despite the Redfield ratio indicating that phosphorus should be the primary nutrient limiting factor, our results indicate that silicate plays the most important role in regulating phytoplankton dynamics in Bohai Bay.

Performance Prediction of a MongoDB-Based Traceability System in Smart Factory Supply Chains.

In the future, with the advent of the smart factory era, manufacturing and logistics processes will become more complex, and the complexity and criticality of traceability will further increase. This research aims at developing a performance assessment method to verify scalability when implementing traceability systems based on key technologies for smart factories, such as Internet of Things (IoT) and BigData. To this end, based on existing research, we analyzed traceability requirements and an event schema for storing traceability data in MongoDB, a document-based Not Only SQL (NoSQL) database. Next, we analyzed the algorithm of the most representative traceability query and defined a query-level performance model, which is composed of response times for the components of the traceability query algorithm. Next, this performance model was solidified as a linear regression model because the response times increase linearly by a benchmark test. Finally, for a case analysis, we applied the performance model to a virtual automobile parts logistics. As a result of the case study, we verified the scalability of a MongoDB-based traceability system and predicted the point when data node servers should be expanded in this case. The traceability system performance assessment method proposed in this research can be used as a decision-making tool for hardware capacity planning during the initial stage of construction of traceability systems and during their operational phase.

Effect of mineral admixture on CO2 emissions and absorption in relation to service life and varying CO2 concentrations

AbstractCarbonation is a critical deterioration phenomenon, particularly for underground reinforced concrete (RC) structures due to the surrounding environment having a high CO2 concentration. This paper presents an evaluation of CO2 emissions and absorption with varying intended service life periods based on actual geometry and mix ratios of concrete for RC underground structures. Four mix ratios of concrete and CO2 diffusion coefficient based micro modelling are considered, and the CO2 emission and storage are evaluated for each step with material production and conveyance. Simulations for the CO2 amount are also performed for varying intended service life periods and CO2 concentrations. As the intended service life increases, the CO2 emission rapidly increases due to the repeated repairs. In order to reduce CO2 emissions, reducing ordinary Portland cement (OPC) by replacing it with a mineral admixture like fly ash (FA) is a crucial point in the initial construction stage, since CO2 storage in use is li...

Linking structural equation modeling with Bayesian network and its application to coastal phytoplankton dynamics in the Bohai Bay

Bayesian networks (BN) have many advantages over other methods in ecological modeling, and have become an increasingly popular modeling tool. However, BN are flawed in regard to building models based on inadequate existing knowledge. To overcome this limitation, we propose a new method that links BN with structural equation modeling (SEM). In this method, SEM is used to improve the model structure for BN. This method was used to simulate coastal phytoplankton dynamics in the Bohai Bay. We demonstrate that this hybrid approach minimizes the need for expert elicitation, generates more reasonable structures for BN models, and increases the BN model’s accuracy and reliability. These results suggest that the inclusion of SEM for testing and verifying the theoretical structure during the initial construction stage improves the effectiveness of BN models, especially for complex eco-environment systems. The results also demonstrate that in the Bohai Bay, while phytoplankton biomass has the greatest influence on phytoplankton dynamics, the impact of nutrients on phytoplankton dynamics is larger than the influence of the physical environment in summer. Furthermore, although the Redfield ratio indicates that phosphorus should be the primary nutrient limiting factor, our results show that silicate plays the most important role in regulating phytoplankton dynamics in the Bohai Bay.

Comparative Study of Prestressed Concrete Girder and Steel Plate Girder for Roadway Over Bridge

Bridge design is an important as well as complex approach of structural engineer. As in case of bridge design, span length and live load are always important factor. These factors affect the conceptualization stage of design. Prestressed Concrete and Steel plate are commonly used for constructing bridges. This project presents the comparative study of prestressed concrete girder and steel plate girder for roadway over bridge. This work includes the cost analysis and design of prestressed concrete girder and steel girder. In the good olden days, for higher spans, steel girders whether plate girders or triangulated girders were pre-dominantly used. After the advent of pre-stressed concrete, its use in higher span bridges increased tremendously. Main reason behind use of PSC girders is due to its initial economical cost. No doubt, PSC girders are economical in the initial stage of construction, but the same may not be true if we consider the life cycle cost including other factors. The aim of this work is to design prestressed concrete and steel girder for various span and then compare the result. . Based on the understanding of the manual design procedure, a computer program in MS EXCEL was developed for designing both prestressed concrete and steel plate girder. The goal of study is to determine most favourable option from above two.

A Proposal of NIA Model for Eco VE Decision of Construction Facilities

Construction industry that was the core driving force of Korean economic growth is now being classified as an industry with the largest environmental load emission. Although various efforts were made accordingly to realize eco-friendliness, its effects is insufficient currently. Based on the understanding that eco effect of construction industry would be significant if Eco VE is applicable in the initial project stage, NIA model for understanding the eco VE decision of project owner was developed with simulations in this paper. Based on the proposal report of a private project to develop the Gyeongbuk Northern Region Environmental Energy Town, 20 questions on eco VE decision were used through simulations. The result showed 50% eco-friendly decision. The result of this study can be used to provide decision-making data for eco design in the initial stage of construction by utilizing NIA upon conducting survey research to deduce eco VE decision.