construction

Today, air pollution is considered as one of the most important problems of human societies. The expansion of urbanization, the development of cities, the increase in population, the increase in construction, the development of industrial activities and the increase in the consumption of fossil fuels, the lack of an efficient public transportation system, the low quality of fuel and the traffic density have caused a large amount of pollutants incompatible with natural mechanisms to be released into the air daily. Air pollution has harmful effects on the environment and human health. The distribution of gases and pollutants in different layers of the atmosphere is not equal. So that some pollutants such as carbon monoxide and sulfur dioxide have a very high concentration in the troposphere layer compared to other layers.  Along with other factors that increase pollutants, the construction industry is also one of the major sources of environmental pollution, responsible for about 4% of the production of greenhouse gases, particles and more water pollution than any other industry. Today, due to the excessive growth of the population and the need for housing, it has required that tall buildings rise every day from all corners of the city. Now this issue causes the production of pollutants to increase in cities. Because the increase in population causes an increase in single-passenger cars and issues in this regard. The increase in population and the desire to seek profit through construction replaces the beautiful and natural landscapes of our country with urban areas every year. Population growth causes an increase in construction in an area, and this problem causes the physical development of urban areas over time. In this research, the aim is to investigate the impact of construction on air pollution in the troposphere and also how the concentration of pollutants changes in different seasons of the year.

The area studied in this research is District 22 of the municipality located in the northwest of Tehran, one of the new areas of Tehran, which was built in order to solve the lack of services in the western area of Tehran and to relocate part of the population living in the dilapidated tissues of central Tehran, and the amount of construction in this area is growing. has been selected and to investigate the construction changes in the study area, the maximum likelihood classification method was used using Sentinel-2 satellite images, and for monitoring carbon monoxide, sulfur dioxide, nitrogen dioxide, tropospheric ozone and aerosol pollutants, Sentinel 5 satellite images were used in the Google Earth Engine system.

The findings include calculating the amount of construction in the years 2018 to 2022 and providing maps of changes in the concentration of carbon monoxide, sulfur dioxide, nitrogen dioxide, tropospheric ozone and aerosol pollutants per unit of time and space.

The results of this research show that from 2018 to 2022, about 33.12 hectares were added to the construction areas of Tehran's 22nd district, and these construction changes did not affect all gases, and only carbon monoxide and carbon dioxide pollutants had a growing trend. Also, the concentration of mentioned pollutants was higher in winter than other seasons.

Increasing the productivity of human resources is one of the main plans of managers in every organization because human resources are the most important capital of every organization. Human resource productivity means the maximum use of skills and human resources. In this research, six functions of recruitment, job analysis, education, performance evaluation, work relationships, and employee services are considered effective factors in human resource management to increase the productivity of human resources. Also, the two variables of job ability and job motivation are also considered mediating variables. The current research is practical in terms of purpose, in terms of the nature of the research, it is descriptive, in terms of data application method, it is part of survey descriptive methods, and in terms of the research implementation process, it is qualitative. In this research, library studies and questionnaires were used to collect information. The statistical population of the research is all employees of contracting companies with grades one to five, numbering 150 people. In this research, the data were analyzed using the structural equation method with the partial least squares approach and using PLS software. The results of this research show that among the six functions of human resources management, the independent variables of job analysis and employee services have the greatest impact and the independent variable of performance evaluation has the least impact on the mediating variable of job motivation. Also, the two independent variables of recruitment and employment services have the greatest impact and the independent variable of job analysis has the least impact on the mediating variable of job ability. As a result, among the two mediating variables of job ability and job motivation, the variable of individual performance is more dependent on job ability.

Transaction costs constitute an essential part of the costs of a construction project (Rajeh et al., 2015). One of the critical factors influencing the choice of project delivery method is the transaction cost (Whittington, 2008). Transaction cost economics has meaningful solutions to reduce transaction costs. So far, it seems that no research has examined how to choose a project delivery method based on transaction cost economics criteria. Transaction cost economics examines the governance structure of institutions based on the three dimensions of specificity, uncertainty, and frequency of transactions (Williamson, 1985). This paper examines how to select the delivery method in construction projects, using the transaction cost economics approach to determine the governance structure. Three methods of traditional (design-bid-build), design-build and construction management are investigated.

Collapsible soils are a category of natural soils that are associated with problems. In other words, under a uniform tension, their volume will be reduced to a great extent due to increasing humidity. This decreased volume will destroy the soil's structure and will finally lead to a significant settlement. The existence of such soils in many parts of the world including central parts of Iran, e.g. Kerman province, requires conducting studies on the behavior and properties of collapsible soils. In this study, the impact of butadiene rubber on the stabilization of these soils has been investigated. The fine-grained soils in this study have been taken from two different sites and they've been stabilized through injecting different percentages of butadiene rubber (number of experiments=84). The stabilized soils have been evaluated through ASTM D5333 double consolidation. Besides, Atterberg's properties have been studied on non-manipulated soil samples. The penetrations of butadiene rubber as well as formed beams of butadiene rubber results in the reduction of studied soil's collapsibility. Furthermore, it resulted in lowering down fluidity property in soils with a high fluidity rate and vice versa, i.e. will result in increased fluidity in low-fluidity soils. Considering the development of smart systems in the prediction of stabilized collapsible soils' behavior, this study predicts the collapsibility potential and Atterberg's limits of soil samples stabilized using butadiene rubber through ANFIS model. The accuracy of this model has been investigated as well and the results are analyzed.

Execution of construction projects despite safety regulations, there are always irreparable risks, including physical and financial accidents for human resources and the project, these events adversely affect the balance of cost, time and quality of projects. Therefore, the existence of safety management system can play an effective role in improving the project management process. This research includes identifying and evaluating the most important levels and safety criteria in construction projects, evaluating and developing a safety management maturity model in workshops based on a case study, statistical analysis of the data obtained from the questionnaire and applying the combined multi-criteria decision making method. It is based on combining Analytical Hierarchy Process techniques, Technique for Order of Preference by Similarity to Ideal Solution and Decision Making Trial and Evaluation. Based on the results of the study, twelve important safety criteria were identified and ranked according to the weighting performed and then among the three projects studied, one of them was selected as the project closest to the ideal solution and at the end, the most effective criteria were prioritized in four pillars. The main project, which includes the leadership and management of the project organization, project partners and stakeholders, key personnel and project staff, policies and strategies, was identified.

The issue of increasing efficiency and improving the executive performance of construction has been one of the goals and concerns of regulatory bodies such as the municipality and the Engineering System Organization. At First, what is taken from the executive supervision concept is that the presence of the building's supervisor is the main responsibility for ensuring the building's quality. But in reality, there are countless factors behind of a building construction process that cause a decrease in the quality of executive supervision and ultimately a decrease in the executive quality of a construction. The main purpose of this article is to review the defined role of the supervising engineer by the Engineering System Organization in the field of construction, to examine various factors in the decline in the quality of executive supervision by statistical data obtained from the community and finally suggestions to increase the efficiency of executive supervision.

Lack of government resources and severe need for infrastructure development facilities, governments need to attract the private sector in the country's infrastructure projects, BOT can be considered a reliable way to attract private capital, our country has also used this method in recent years. For all its benefits to the BOT system, there is plenty of experience with BOT projects around the world that has failed or at least failed to achieve its intended purpose; They warn us in choosing this method. The aim of this study was to investigate and rank the risks inside and outside the project in BOT projects using library studies and combining it with field surveys. The continuation of identified risks is analyzed and prioritized using expert opinion collection. For this purpose, a questionnaire was used and to analyze the results and data obtained from the field survey, SPSS24 software was used as the most powerful statistical analysis software and to deduce the results. From the field survey, Heider test was performed on the accuracy of the answers, the validity and reliability of the answers. In order to check the normality of the data, skewness coefficient and elongation coefficient, in order to optimize the variables, one-sample t-test, etc. were used.

Construction projects in the oil and gas sector require a heavy budget and a long construction time. As construction projects become larger and more complex, new planning methods are needed. The use of traditional planning methods for project management has not been responsive, and most projects face problems such as widespread delays, cost overruns, rework, wastage, and inadequate resource utilization. One of the challenges of oil and gas projects is the issue of delay and inadeqate resource utilization. Traditional planning techniques such as Critical Path Planning or PERT do not meet all linear projects' requirements. Planning for construction projects is often performed in a critical manner. In this way, the impact of resources and machinery is not well understood, and the uncertain nature of construction projects is not applied. In linear projects, similar activities are repeated in different positions. Pipeline construction projects require effective planning to ensure maximum utilization of resources and reduce time outage due to the constant movement of resources and machinery. Completing projects at a specified cost and time requires proper planning that the project can deliver on time. The current research introduces a framework to improve gas pipeline project planning using modern computer tools such as construction simulation. This framework aims to examine the impact of the number of resources on the project process, estimate realistic project duration, increase resource productivity, carefully evaluate construction operations, and ultimately reduce project time and cost. This framework would enable project employers and contractors to have greater flexibility in planning discussions and increase their supervisory capacity. The framework is presented in collaboration with the Iranian Gas Engineering and Development Company in the form of a case study of the Dehgolan to Miandoab gas transmission pipeline.

Building Information Modeling (BIM) has been created to increase the efficiency and use the abilities of the digital tools in construction projects and is improving more and more. In addition to the benefits of this technology, some new challenges have been rosed most of which are related to legal and contractual issues. The routine contracts of the construction industry cannot respond well to the special situation of BIM, and various approaches have been proposed at the international level to resolve this problem. Some of them are under investigation and research to reach an appropriate solution. A specific contractual framework has not been codified in Iran, either. The study of these approaches fulfilled separately and scattered all over the world is a necessity that must be analyzed to present an explicit viewpoint for the decision-makers to achieve an appropriate approach for BIM contractual framework codification. This study investigates 21 cases of the proposed approaches in 7 leading countries in this field (BIM) and receiving the domestic industrial professionals’ comments, has compared these approaches and categorized their advantages and disadvantages. The results of this research showed that providing “the contractual appendix of BIM” and its attachment to the existed contracts can be an acceptable approach for removing the contractual problems of BIM. In the end, some proposals were presented for the manner of an appropriate contractual framework along with the country's situation and requirements.

Economic tools are definitely an effective way to encourage or enforce contractors to enforce environmentally-friendly practices. Previous studies on this subject mainly focus on the management of waste of construction and demolish (C & D) from the static point of view, which does not take into account the nature of its dynamic by taking all necessary activities in the waste chain. Therefore, the purpose of this paper is to explain the dynamics and relationships between the components of C&D waste management and to analyze the costs and benefits and cost of transportation and fuel consumption using the system dynamics approach. The findings show that the implementation of C&D waste management has many benefits, but the higher cost of landfill at authorized sites will result in more net profits, which will be accompanied by disadvantages such as environmental damage. In addition, the public is suffering from landfill in unauthorized locations and imposing environmental costs due to illegal evacuation. Simulation results also show that increased landfill in unauthorized locations increases fuel and energy consumption and therefore increases fuel consumption costs. This study by investigating and evaluating the researches and measures taken on the waste and waste spillway aims to clarify the use of a systematic approach using the dynamics of systems in a direction in which it is possible to use contract cost-benefit analysis to encourage contractors to disposal of Construction waste in a way that is conducive to the development of the building industry and the preservation of the environment and the resulting savings.

Risk management in urban projects is a complex task whose complexity depends on the size of the quantitative and qualitative dimensions of the urban project. Urban projects in the current market and business conditions are exposed to crisis at any time. The environment of urban projects is very variable and the conditions of uncertainty are many, and these conditions become more difficult for larger urban projects. Undoubtedly, proper management of these risks is a prerequisite for facilitating the crisis conditions of urban projects, and the need to access and expand the related sciences is quite obvious. This article examines the effect of variables such as age and occupation on risk-taking in urban project management, analyzes the relevant principles and challenges, and by conducting a study on the workforce in Shiraz Municipality, examines each Which of the independent variables of age and occupation dealt with risk-taking and its factors and finally led to the conclusion that none of the independent variables of gender, age, level of education and occupation had a statistically significant effect on risk-taking and its factors.

Obstract:Since achieving the goal in implementing construction projects on several bases of management,budget,time,manpower and ..... and this goal is well_done when they have any project benchmark .Then the desired plan and idea of the employer has been viewed and it will be at the discretion of the benefits that are mostly the general public.Management begins with the plan as an idea and then examines in diffrent phases and ultimately its desirability goes.The necessity of using construction systems and new materials has been made to increase the speed of construction,lightness,increase the vitro,as well as the resistant to earthquake buildings. In this regard,promotion f the scientific and specialized level of country engineering community and familiarity with new construction systems and materials is invitable.Solving problems such as long run,low useful life,or high cost of running buildings in the housing sector requires providing solutions for practical use of new construction systems and new building materials.To reduce weight,reducing the construction time,more durability and ultimately reduce cost. This long_term measures will optimise build,increase the housing production in the country and reach the condition of optimal implementation.On the other hand,such developments will extend the underlying investment or all principles in the housing sector,especially by the private sector.This will help the government in reaching its goals in the housing sector.In this study,we try to examine the characteristic of composite engineered in the form of qualitative management guarantee,quality construction project.According to the paper and sample,the research method is used to analyse the methodology and library tools and documents and continuous studies have been used;considering the engineering composite characteristics,we can meet our demands against construction technology. KEYWORDS:ecc,engineering composite,project management and construction,qualitative management,new technology.

Construction is one of the most important issues in a society economically, socially, culturally and so on. But the issue of quality in the construction projects requires discussion takes more scientific. The objective of this study is to investigate the optimization of the quality of construction projects and construction costs based on system reliability theory. Also, a real construction project is presented to evaluate the efficiency of the proposed model. In order to achieve this goal, a four-step algorithm is defined and proposed model using two methods M3AS and classic ant colony algorithm is solved. The results of both methods are compared. Parzin five-story residential building located on Zaferanieh Street is studied. The results indicated that M3AS innovative approach through local search is more capable than the classical ant colony algorithm for optimization. Most previous studies have not considered the importance of the quality of project. In this study, quality in the form of reliability at the time of completion of the work is quantified. The proposed model has been so overcome lack of expression and effectively using reliability theory. This model can automatically produce reliability and optimal cost of system with regard to structure function of reliability and non-linear function of cost-reliability. In this study, multi-objective optimization model based on reliability theory extends to decision-makers to determine and choose between cost and quality for construction projects. Since a major part of the annual budget allocated to construction projects, these projects are the most important component of the country's development that must be managed properly in terms of cost and quality and be completed according to the schedule. iT is clear that the status of the construction industry in terms of quality and cost should be much improved.

Nowadays, the existence of limitation in urban spaces, the requisiteness of consideration to land use from the environmental and social perspective, as well as the necessity to develop the urban transportation network, has forced those involved in urban management of cities to use underground spaces as one of the best alternatives. The usage of these infrastructures in developed countries, has led to the very well results on reducing the traffic and urban transportation issues, which unavoidably necessitates their application. On the other hand, the potential of the occurrence of hazards and incoming risks on tunnels has always been considered as the main challenge of tunneling in each three phases of design, construction, and operation, and with regard to the remarkable costs related to construction and operation of these establishments, the identification of these hazards and investigation of their impacts on tunnels has a particular importance on reducing the probable damages. In phases of design and construction, the investigation of types of hazards on urban tunnels shows that hazards such as the occurrence of mistakes in planning stage such as preparation of technical specifications and estimation of design parameters; computational and numerical mistakes; managerial and controlling mistakes; the occurrence of errors and mistakes during the construction phase of tunnel; hazards due to unknown situations of underground spaces; the existence of underground water; entrance of water and flood; effects of earthquake on tunnel; and hazards due to subsidence as well as the gases must be considered in the risk management and securing the safety of urban tunnels.