جستجوی مقالات مرتبط با کلیدواژه « maintenance » در نشریات گروه « عمران »

Rural roads and passages form a major part of the country's roads, which play a constructive role in the quality of traffic and the relative well-being of the villagers. This research was carried out in a descriptive way and by reasoning to books, sources and authentic library texts and by collecting and referring to field studies taken from objective observations as well as their analysis, which aims to develop and expand quality pavement as well as Introducing the correct methods and solutions for prevention and timely maintenance of the failures in the asphalt paving of rural roads. In this research, major damages in rural roads and roads were investigated and analyzed to find the best way to repair them. The obtained results indicated the existence of major damages including alligator cracks, block cracks, longitudinal and transverse cracks, corrugation, potholes, etc. It has been proposed, for alligator cracks, as the most common cracks, the staining method, apply seal coat and improve the load-bearing condition of the subgrade soil, and for other defects, various methods to improve the condition of the defect have been presented in detail. It is easy to minimize the damage caused by most of these failures by properly monitoring the implementation and sufficient precision in the design. By carrying out a basic and technical design of a suitable pavement as well as its correct implementation, it is possible to use that pavement properly for many years. Proper attention and planning to use suitable maintenance options is very important.

Nowadays, increasing useful service life, durability and maintenance of road pavements are important research issues of experts and trustees in this field. The purpose of this research is to investigate and prioritize the factors affecting the useful life of suburban road pavements with a fuzzy hierarchical approach for the Ghaemieh -Shiraz route. The research method was descriptive-survey in terms of execution and applied research in terms of purpose, which was done in the form of a questionnaire and quantitative. Due to the fact that the topic of this research was a specific topic in the field of road construction (engineering and roads), non-probability sampling was a judgmental type. The statistical population of the research included 12 experts, including specialists and engineers in the field of road construction in Fars province, and the fuzzy hierarchical analysis method was used to prioritize the effective factors. The results of factors affecting the service life of suburban road pavements showed that the type of bitumen and materials used, contractor, road construction equipment and machinery, weather and the type of traffic vehicles ranked first to fifth in the order of factors affecting the service life of road pavements. They were in suburban areas on the road from Ghaemieh to Shiraz, that practical suggestions for the useful service life of suburban road pavements for Ghaemieh -Shiraz route were presented.

The growth of railway lines has caused engineers to seek to increase the efficiency of the ballasted railway track, and for this reason, they are looking for an increase in the maintenance intervals and a lower life cycle cost. In high-speed railways and lines with high traffic volume, especially railways with stiff and soft subgrade, the issue of line settlement is one of the challenging factors. According to the methods introduced to strengthen the subgrade so far, the use of geogrid is one of the conventional methods to reduce settlement and maintenance operations, which today requires more investigation in its optimal selection. In this article, an attempt has been made to investigate the effectiveness of geogrid to reduce stresses on the subgrade, sub-ballast layer, and ballast layer, and to explain how to choose it based on the technical parameters. In this study, the types of geogrid and the effect of mesh size, applied stress, and its effect on soil resistance have been investigated and the method of achieving the appropriate selection of geogrid has been suggested. Studies show that by using geogrid, the vertical settlement and horizontal movement of the railway panel can be reduced by 70%.

Failure to define the indicators and sub-indicators for measuring the performance of Repair and Maintenance (R&M) activities is one of the significant issues in a building to increase its life expectancy. Evaluation of R&M system in a building is one of the key factors in improving the quality of R&M performance steps. Therefore, to implement appropriate strategies, the criteria affecting on R&M system must be identified. Also, choosing the proper net policy is a strategic decision-making problem that effectively reduces the cost and longevity of buildings. In this research, by using the experts’ opinion and the Delphi method, the indicators and sub-indicators affecting the R&M system were identified, and those indicators were graded using the decision tool. The existing buildings in Karaj city as a case study were then considered to evaluate the proposed system. Analysis of the results shows that the safety index has the highest grade according to the experts’ opinion, but by reviewing the results of the case study, this rank was assigned to the health criterion. Then, by using the SWARA technique, the most critical policies affecting buildings’ R&M are identified among Emergency Maintenance (EM), Breakdown Maintenance, Corrective Maintenance (CM), Preventive Maintenance (PM), Predictive Maintenance (PdM), Total Productive Maintenance (TPM), Proactive maintenance. Applying the VIKOR method and the results of both approaches revealed that Corrective Maintenance (CM) and Breakdown Maintenance (BM) policies are the best for buildings, R&M policies.

Nowadays, increasing useful service life, durability and maintenance of road pavements are important research issues of experts and trustees in this field. The purpose of this research is to investigate and prioritize the factors affecting the useful life of suburban road pavements with a fuzzy hierarchical approach for the Ghaemieh -Shiraz route. The research method was descriptive-survey in terms of execution and applied research in terms of purpose, which was done in the form of a questionnaire and quantitative. Due to the fact that the topic of this research was a specific topic in the field of road construction (engineering and roads), non-probability sampling was a judgmental type. The statistical population of the research included 12 experts, including specialists and engineers in the field of road construction in Fars province, and the fuzzy hierarchical analysis method was used to prioritize the effective factors. The results of factors affecting the service life of suburban road pavements showed that the type of bitumen and materials used, contractor, road construction equipment and machinery, weather and the type of traffic vehicles ranked first to fifth in the order of factors affecting the service life of road pavements. They were in suburban areas on the road from Ghaemieh to Shiraz, that practical suggestions for the useful service life of suburban road pavements for Ghaemieh -Shiraz route were presented.

The present paper aimed to develop a bridge management system using a combination of new fuzzy multi-criteria decision making methods. The developed system consists of a three-phase protocol. In the first phase, using past studies, personal intuitions and judgments and experts' experiences, a database containing critical factors affecting the critical condition of bridges was prepared, as well as identifying a number of urban overpass bridges in Tehran city with relatively similar characteristics and in need of maintenance. In the second and third phases, considering the uncertainties in the decision-making problem, by combining Delphi-SWARA-ARAS methods in a fuzzy environment, while screening and prioritizing more efficient and effective critical factors, the critical situation was assessed and the steps studied were selected. The results of Fuzzy SWARA method to determine the effective final factors showed that the factors of seam filling and discontinuity of the bridge related to the main structural index, average and duration of maximum annual rainfall at the bridge location of the main index of climate and hydrology, drainage, water discharge Surface and insulation of the bridge from the main index of safety, proximity and convenience of bridge access to adjacent arterial roads in terms of the main index of strategic (regional) importance, cost-benefit ratio for maintenance or reconstruction and replacement of the bridge from the main budget index and finally The volume of traffic passing over the bridge has gained higher ranks than the main index of traffic and pavement, respectively. Also, the results of Fuzzy ARAS method based on final critical factors (18 factors) showed that among the 24 bridges, Sheikh Fazlollah-SattarKhan, Hakim-Sheikh Baha'i, Hemmat-Africa, Lashkari-Aircraft industries bridges And Resalat-Haqqani with usefulness of 3.226, 3.171, 3.081, 3.080 and 3.077, respectively, are considered as the most preferred bridges in terms of the need for maintenance allocation.

Road network is one of the main infrastructure developments and it is considered as the national capital. Maintaining this huge capital requires long-term planning and continuous activity of maintenance. In the past, traditional maintenance methods were focused on activities intrinsically or structures. Because preventative maintenance measures to increase pavement life-time service-systems and decrease the cost of long-term facilities, the theory carry out maintenance before the start of the collapse of the pavement is been considered by managers. Crowded intercity routes of Mazandaran province, especially in the tourist region studied in this research that was chosen because of high traffic and vehicle traffic. In order to solve this issue, after coding in MATLAB software, based on mathematical models and algorithms different states based on different period, the number of choosing the path of repairs category and a limited budget is defined, then desired results is obtained. The characteristics of solutions is defined in different states and changes in cost, utility and total number of selected routes as well as maintenance paths of selection from each category is analyzed.

Maintenances are necessary to ensure the safety and serviceability of existing bridges. With the increasing number of existing bridges, maintenances cost a large proportion of financial fund and have significant impact on environment. Bridges like any other structure and perhaps more than most of them are affected by environment. Because they belong to sensitive and high costly structures, failure to maintain them will have devastating effects. Bridges are needed continuous maintenance in order to service properly during its life cycle. Therefore, in this study, the issue of maintenance and repair of urban bridges in Mazandaran province has been studied with regard to life cycle cost and reliability of bridges. To do this end, a mathematical programming model which is include minimizing maintenance and user costs as well as maximizing system reliability. In order to solve the proposed model, a multi-objective particle swarm optimization algorithm is developed. Also, a sensitive analysis is done on failure rate. Results show that increasing in this parameter cause to increasing cost and decreasing reliability, This indicates that the proposed algorithm is working properly and the results of this research can be trusted.

Evaluation of maintenance system in the building is one of the key factors in improving the quality of maintenance and repair processes. It can be stated with certainty that all buildings need maintenance and scientific and technical repair after construction, and therefore how to define this system and determine the appropriate indicators and strategies for it will play an important role in the cost and longevity of the building during operation. The purpose of this paper is to identify and prioritize the indicators affecting the maintenance and repair system (R&M) of Residential buildings and determine the most appropriate policy related to it using a combination of multi-criteria decision-making method. In the presented method, first the weight of the indicators was calculated and then the indicators were prioritized based on multi-criteria fuzzy and non-fuzzy decision-making methods.Finally, considering the ranks obtained from those methods, the final ranking of indicators was calculated using the Average rating and Copeland method. The results showed that the indicators of safety, health, accessibility and proper utilization are in the highest priority respectively and reliability are in the last rank. This issue indicates the importance of safety indicator in evaluating the maintenance and Repairs system of buildings. in order to perform maintenance and repair operations, by identifying and prioritizing effective indicators, they can be used to evaluate the maintenance and repair system of the building based on them.Finally, according to the results and with the help of ARAS method, Breakdown Maintenance Strategy was selected as the most appropriate maintenance policy for buildings.The results of this study show that the application of multi-criteria decision-making methods can help the construction industry professionals to select the key effective indicators in the repair and maintenance system and determine appropriate strategies. Finally, suggestions for future research were provided.

Failure detection of complex industrial equipment such as locomotives is a challenging tack in maintenance process. Failure to timely diagnose the cause of locomotive failure, in addition to reducing access time, will cause disruption to the rail network, increase excess train stops and other adverse events. With the advances made in recent years, the amount of data stored in new locomotives is increasing. In different ways, the knowledge contained in the data can be extracted and used to increase the productivity of the organization. By pattern analysis of failure detection of locomotives, the cause of many failures can be discovered and repair time can be reduced. Among the available methods, data mining techniques can be mentioned. The present study uses data mining and Apriori algorithm to discover meaningful rules from the data in locomotives, with the aim of improving the efficiency of the failure detection process. The result of this study is the discovery of 20 frequent occurrence in passenger locomotives, 18 two-component laws and 2 three-component laws, and its key achievement is the improvement of locomotives maintenance in a short period of time in the Railway of the northeastern region of Iran. Use of the discovered laws in the future can eliminate many out-of-schedule stops of passenger trains and also significantly reduce the cost of locomotive maintenance. It is estimated that using only one of the mentioned laws alone can reduce the cost of Iran's railways by about ten billion rials per year.

Roads are one of the most important assets in each country. Road network are too extensive and the budget needed for reconstruction is too high. To maintain these properties planning for the maintenance and rehabilitation is an important issue. Aging, traffic (especially trucks) and weather condition in the region cause numerous tensions in the pavement. These tensions are the main reason of distress, reducing ride quality and finally deterioration in the pavement. Because of the increasing rates of the costs associated with maintenance and repair there is a concern about keeping roads in good condition with the lowest costs. The main purpose of this research is to apply an evolutionary model to minimize the costs of maintenance and repair operation and at the same time maximizing the benefits of the system for a long time with acceptable service quality. The models are assessed on the hypothetical networks and the results have been satisfactory..

Today, the structural health monitoring system based on various non-destructive analysis and tests has been greatly expanded in order to better performance and prevent further damage to the structure especially in areas with high seismicity. Given that, various structural health monitoring systems have been introduced. On the other hand, the discussion of maintenance costs with these methods can be helpful in choosing the most optimal method for this purpose. To this end, five new systems for health monitoring of structures, including the method of examining changes in basic information; Finite element model upgrade method, acoustic and ultrasonic method, magnetic field method and thermal field method were selected in 5 categories: management, technical, economic, human source and safety along with 20 sub-criteria in the field of maintenance. Then, through the pairwise comparison questionnaire of analytic hierarchy process method and receiving the opinions of experts in this field, different structural health monitoring systems were evaluated and prioritized to select the optimal system based on the most important criteria of building maintenance. The results showed that the structural health monitoring system by finite element model method has gained the first rank in all 5 main factors of management, technical, economic, human source and safety.

Reliable and accurate assessment of the condition of the pavement network such as International Ruggedness Index (IRI) and pavement condition index (PCI) is one of the most important components in a pavement management system. This issue is very effective in managing and planning financial resources to maintain road pavement. However, calculating PCI and IRI parameters are difficult and complicated. Therefore, it is necessary to use numerical models to estimate these parameters. In this study, PCI and IRI data related to five different freeways in Iran were used and different mathematical models were investigated. Afterwards, a model for estimating PCI data from IRI was introduced, which had an acceptable correlation between these data in all the freeways studied and Showed better performance than out of all the models presented by various researchers in the world which mentioned in this article. The use of this model can make it possible to estimate the PCI parameter for the freeway networks, and as a result, the management of freeway pavements and planning for maintenance operations will be facilitated at a lower cost.

Given the importance of the repair and maintenance process in keeping equipment and facilities ready for use, it is necessary to assess the process and performance of maintenance indicators regularly so that the repair and maintenance is planned and upgraded. The main purpose of the building repair and maintenance is to control the equipment, facilities, and various building components to determine productivity and optimize their ability to achieve the highest efficiency. As measuring the efficiency is one of the most important performance evaluation methods, evaluating the efficiency of the repair and maintenance is one of the qualitative factors to improve this system. The purpose of this study is to evaluate the efficiency and performance of the repair and maintenance in buildings using a quantitative and provable data envelopment analysis (DEA) method. The results of this study show that the DEA is a suitable method for evaluating the efficiency and productivity of the decision-making units (DMUs).Therefore, first, the questionnaire is formed based on the building repair and maintenance system parameters extracted from Topic 22 of the National Building Code, the ranks are determined, and the results obtained from the sub-indices are integrated by the mean ranking index, and the qestionnaires’ reliability is measured using Cronbach's alpha. Finally, after defining the input and output indices by the DEA, the efficiency of each building and its cost are determined based on the repair and maintenance indices(In a case study of the city of Karaj). The results showed that the minimum and maximum reduction of the cost of charging, maintenance and repair of the building to convert them into an efficient building is 1% and 80%, respectively. Moreover, based on the results, it is possible to provide suggestions to improve the efficiency of the inefficient buildings based on the repair and maintenance costs.

Roads are vital channels for social life in any country and their good state is one of the mainrecognized criteria of country’s development and progress. These routes must be constantly instandard conditions in terms of serviceability and provide safe and comfortable transport forusers. One of the key goals of the organizations involved in road construction and managementis to delay the occurrence of distresses and increase the useful life of the road network throughmaintenance operations. This goal is achieved by optimizing maintenance and rehabilitation(M&R) planning at the network and project levels. In this study, a method for selecting theoptimal M&R option for freeway pavement sections in each time period is presented. Usingdistress data, the pavement status prediction models based on IRI and PCI indices are presented.Also, one-year and multi-year M&R program of pavement maintenance and rehabilitation ispresented based on these prediction models. Finally, maintenance plans are provided in thepresence of budget constraints that will reduce maintenance costs and maintain optimalpavement conditions through the years of operation.

In the road maintenance system, there are several options for repair and maintenance. But due to resource constraints, one should take into account the various options available to provide the lowest cost with the desired goals and prevent future losses. The purpose of this study was to investigate the management of rural roads in Mazandaran province. One of the most important steps in the management system is to evaluate the current conditions of the pavement, which uses a variety of indicators. One of the indicators derived from the analysis of failure data analysis is the PCI index, which is one of the best indicators for assessing the failure of Iran's roads. In this research, after field observations and evaluation of failures and analysis with Micro Paver software, it was determined that rural road pavements had "suitable conditions" with an average of 76PCI. Asphalt pavement, which represents 87% of the pavement inventory, had an average PCI average of 74. Concrete pavements, which constitute 13% of the pavement inventory, were slightly higher than the 87 PCI. The results indicate that the projected budget is currently 2.0M / YR (approximately), possibly leading to a 6% decline in the overall PCI, as well as an increase in M ​​& R stagnation over the next five years. The 7.1 M / YR budget was set to eliminate the recession, which achieved the lowest total cost during the five-year analysis period.

The safety of bridges as the vital arteries of cities is of great importance. There are several factors that raise concerns about the safe performance of bridges, and resolving these concerns are dependent on the appropriate decision-making of urban managers throughout the service life of bridge. These factors can be divided into two major types. The first type are factors affecting the safety of a part or whole structure of bridge and producing concerns about the bridge collapse. For easing the danger of collapse, totally or partially, a proper decision should be made to improve the behavior of a specific part of bridge at a certain time during its service life. The second type are factors influencing the safety of one or more bridge elements and increasing the life cycle costs of bridge. To prevent the growth of bridge costs due to deterioration, an appropriate plan for repair and maintenance should be implemented in order to enhance the condition of one or several elements.  In order to make the right decision, it is necessary to obtain accurate information on the condition of bridges. One of the best ways to get this information is to use bridge health monitoring. Health monitoring is the process of information acquisition from structure by installing sensors on its components and analyzing the data obtained from implemented sensors. By bridge structural health monitoring and interpreting the gathered data, the access to accurate and timely information, which is consistent with the reality of the bridge structure, is provided. Having the correct information about the bridge, the managers can decide at a lower level of risk. However, choosing specific monitoring strategy among different health monitoring systems for a bridge is a challenge that should be solved. A Quantitative index is needed to find the best technically and economically monitoring system.  The value of information (VoI) analysis is used for determining the effectiveness of monitoring information in decision-making. VoI is a method which quantifies the price of information and specifies the cost-effectiveness of decisions made on the basis of monitoring. This analysis also makes it possible to choose the most economical monitoring strategy among several alternatives. In the VoI calculation, all the uncertainties involved in the performance of a Health monitoring and probabilities of any anticipated event are considered. Thus, the decision making based on VoI is risk-based and reliable especially for important structures like bridges. In this paper, after investigating the worries and solutions for eliminating worries about the bridges in detail and introducing the applications of structural health monitoring (SHM) systems for bridges, the equations governing the VoI analysis is presented and the procedures for determining the VoI is discussed, and as an example, the VoI analysis of a bridge is discussed. According to the results of this analysis, implementing a specific amount of strain gauges with specific accuracy can provide worthy information about the bridge safety for the manager. Moreover, by the VoI analysis, the best approach for sensing system of SHM in the bridge is determined.

Maintenance and rehabilitation planning plays a pivotal role in the implementation of efficient pavement management system. The variables are generally considered deterministic to solve the problem. Nevertheless, this problem tackles with high level of uncertainty. For instance, the budget, as one of the essential criteria, is fluctuated owing to resource limitation, and policy alteration. If the budget is taken into account as deterministic, the result of problem may be considerably different from the absolute optimal solution to the problem. This investigation aims to solve maintenance and rehabilitation problem by consideration of a novel and powerful uncertainty approach. To this end, a multi-stage integer linear uncertainty model is introduced in order to find a solution, which is feasible and optimal in all of the uncertainty modes. The case study of this paper is a network including six pavements. The outcomes indicate that the proposed model is competent to consider budget fluctuation, and it introduces a solution that is optimal for all uncertainty scenarios. The comparison of deterministic and uncertainty models reveals that the number of preventative maintenance selected by uncertainty model is more than that of deterministic model. The number of preventative maintenance is increased from 36.67% to 40.91% if uncertainty is considered in the problem, and it can be postulated that the uncertainty model tries to allocate budget to more segments so as to reduce the likely negative impacts of budget fluctuation on the project.

Roads are considered as one of the most extensive civil infrastructures and national capitals of each country. Pavement maintenance and rehabilitation (M&R) management is one of the most important problems, which can help reducing further costs. Two issues are important in the field of road maintenance and rehabilitation management; first type of M&R option and then time of applying it. In this paper, we have attempted to combine prioritization, artificial intelligence and optimization methods to select the optimal option for maintenance and rehabilitation of pavement sections at any time interval. For this purpose, the analytical hierarchy process is used to prioritize the branches of the pavement network. In the next step, using the linear programming model, the probability of selecting maintenance and rehabilitation options for pavement sections is maximized considering several specific constraints. Fuzzy inference system is used to determine the probability of selecting each maintenance and rehabilitation option in pavement sections. A case study in Mahan (Kerman) is used to run the proposed model. Based on the results, it can be concluded that the proposed algorithm can consider different parameters and indices for pavement branches and sections. In addition, it offers different scenarios for selection of M&R options in a year. The model helps comparing various scenarios based on different budgets for each year. In all, the proposed algorithm facilitates the process of selecting M&R options in the different sections of a road network and provides a scientific approach to manage maintenance roads.

The safe movement of the rail rolling stock is not possible without train control systems. Train control systems ensure safety somehow and they play a vital role in increasing the speed and the capacity of the transport; So that, the failure of the whole or part of it can cause safety disruption, reduce productivity and increase line blockage. Due to the fact that all train control telecommunication services are based on optical transmission networks, the interruption of these networks will cause the interruption of all train control services and as a result, the line will be blocked. Therefore, evaluating and improving the sustainability of the optical transmission infrastructure is essential. In this research, in order to predict the number of the blockages due to the disruption of the transmission infrastructure, the rail transmission network is evaluated in two stages. In the first stage, the parameters of Availability, Reliability and Maintenance (RAM) of the railway transmission network are evaluated, and are simulated using the Monte Carlo method. In the second phase, the RAM mechanism is simulated again by implementing a network failure repair reduction model. In both stages, the probability of the shutdown of the railway telecommunication network, the numbers of blocked lines have been obtained. Predicting the number of network outages and rail line blockages due to the interruption of train control services has been conducted for the first time in research. The results of this study showed that a 10% reduction in network repair time led to a three-and-a-half-fold increase in RAM levels and a 70% reduction in line blockage. These results will be of great value in increasing system efficiency as well as the satisfaction of the users.