جستجوی مقالات مرتبط با کلیدواژه "تعمیر و نگهداری" 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.

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%.

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.

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.

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.

Increasing impermeable levels has made water control a great challenge. On the other hand, the increase of impermeable surfaces causes the lack of heat exchange of the underground layers with the air, which will increase global warming. One solution to this challenge is to use porous pavements. Advantages of porous pavement compared to the normal pavement; Only on run-water control, he can easily increase the use of the road, increase the main road and increase the road, and so on. Restrictions on porous concrete include restrictions on use on high-traffic roads or heavy traffic loads; In other words, with the current knowledge about this pavement system, it can be used in fewer traffic routes such as local roads and streets and parking lots. The purpose of this study is to investigate aerated concrete and get acquainted with the standard related to aerated concrete. Also in this research, the advantages and disadvantages of porous concrete, construction, maintenance, and common problems of this system have been required. At the end of this research, only to gain general knowledge about aerated concrete and aerated concrete pavement mix design, common maintenance methods of porous pavement, and common tests in the relevant researches are introduced. In the end, it was concluded that with sufficient knowledge, porous concrete pavement can be used on roads with low traffic or light traffic load.

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.

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.

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 bridges with any form of structure that are designed and made with any kind of materials that are being manufactured, sooner or later, appear in their burnout effects, but in the type and extent of these exhaustions and their expansion, there are several factors such as conditions Atmospheric, flood or earthquake occurrence, increase in load over design, design quality, and type of materials affecting all of these factors, if not addressed, will lead to a reduction in the useful life of the structure. Therefore, handling bridges and timely maintenance of them will increase the useful life of the bridges. In this research, the evaluation bridges of Mazandaran province has been considered for the needs of maintenance. In order to carry out this research, firstly, the field visits of high importance bridges in Mazandaran province (more than 100 bridges have been investigated and evaluated in this research), and the failure and defect status of each of these bridges As well as the condition of these bridges against the factors such as traffic load and river bed, were studied. After conducting field visits and collecting the required results, we have studied the priority of each of the bridges in Mazandaran province regarding the need for maintenance. Also, in order to determine the amount of costs necessary for the maintenance of bridges, experts in this field were used and each bridge was evaluated separately and finally the amount of repair cost needed for each bridge was identified.

Todays, transportation is one of the main elements of economic prosperity in the world and railway is one of the most important methods of transportation in Iran and in the world, which the main reason of its utilization is the appropriate cost against the capability of a great mass of goods and a large number of passenger’s transportation. Population growth and development of economic relations have led to increase utilization of transportation infrastructures, especially railways. Our country is not an exception and knowing that the railway system is one of the oldest transportation arteries, it is in danger of amortization and destruction. Bridges, as the most important road and railway infrastructure, have the most vulnerable in utilization increase phenomena that some signs of vulnerability are seen in parts of the railway system in recent years, and set the authorities thinking. The important point is that if regular maintenance and retrofitting programs in order to increase the capacity of these bridges are not arranged, it will lead to irreparable consequences. In order to help Iran bridge management system with considering all above issues, the present study prioritizes the need for maintenance and also optimization of corrective actions of the bridges of Zirab – Gorgan part in Garmsar – Gorgan line of north and north-east 2 Islamic Republic of Iran railway by the study on them. To do that, the multi – objective particle swarm optimization Meta-heuristic algorithm is used for the optimization of corrective actions. Also considering the four scenarios to select the number of bridges under repair and 16 conditions of problem to be solved by the defined algorithm, the proper and optimized conditions is introduced in different scenarios and budgets to use in maintenance strategies and the most effectiveness achievement.

Transportation and transportation of goods and passengers in each country is one of the key components of its socio-economic development, and it accounts for a large part of the national budget. Due to the high speed of air transportation in the movement of goods and passengers and its impact on economic development, it has been very important in planning the transportation of the country and has always been of great importance. In this regard, the construction of the airport as a place for the maintenance, assembly and take-off of various types of passenger, military and commercial aircraft is inevitable, and ground facilities are an integral part of the airports, the most important of which is the pavement system. Considering the importance of airports and maintenance of flight levels, this study identifies and prioritizes the effective factors in this regard, which uses a qualitative and quantitative Hierarchical AHP methodology. The results of this study include the number of flights, the implementation of rubber de-mining operations, the type of aircraft, the alternative runway and the history of repairs.

Bridges are the most important and influential infrastructures in urban transportation networks. Isfahan transportation network has many bridges having important role in the performance of the network. Felezzi Bridge is one of the most important bridges at this network because of transferring traffic flow from north of the city to south and vice versa. Construction of this bridge was finished at 1959. At this study the impact area (10% traffic flow change range at the peak hour in 1393) was determined by omitting this bridge from the network in TransCAD software. Then scenarios and indicators were introduced to evaluate. Scenarios were assigned to the model. Then indicators was calculated for each scenario and converted to costs to compare with each other. Indicators were divided to 3 groups according to payers. These payer groups contain users, public and agency. User indicators are travel time, fuel and vehicle operation cost. Public indicators include crash costs, air pollution and noise pollution. Agency indicators are maintenance and construction costs, traffic service and facilities costs. The analysis period is until the end of bridge operation life (2029). Scenarios increasing supply reduce travel time but increase fuel and vehicle operation costs. Results show that summation of costs for users increase at these scenarios and demand management scenarios have lower costs for this group. On the other hand in public costs, crash and air pollution costs are reduced by operating supply enhancement scenarios and noise pollution are increased. It is clear that supply enhancement scenarios have more cost for agency than demand management scenarios.  

Repairing and maintaining roads are among the necessary steps for improving their physical conditions and play important roles in pavements’ life cycle analysis. This issue starts from the first year of roads utilization. Considering this fact, a great portion of annual civil development national budget is allocated to the repairing and maintenance of roads. What is worth considering is a well-devised technical and economic plan that could prioritize improvements and maintenance expenses. In this research, the prioritization of roads pavements repairing and maintenance has been fulfilled with the use of the thorough practical software HDM-4. For this purpose, Kelarabad-Abbasabad road was considered as pilot (due to the similar problems of other city roads in the Province, this case study can be extended to other cases as well). A detailed analysis of software input data including expenses, traffic network configuration, and road networks was conducted. HDM-4 results prioritized the proposed options in two scenarios; a free budget scenario which introduces the most technical option, and a budget-restricted scenario which introduces the most economic option. Given the results of this software and net present value (NPV), the most economic option was introduced for Kelarabad-Abbasabad road as sequent repair and maintenance of pavements in accordance with the needs of the users and employers. Considering the findings, the software introduced patching, seizing, cracking and rebuilding (10cm) for the budget free scenario. For the budget restricted scenario, the software proposed patching and cracking.

Bus stations are the most important and effective parts of the public transport system in the attraction of passengers. Providing an integrated solution for maintenance, identification of problems, and reforming these shortcomings are very important in the urban transport management. In this paper, it is tried to prioritize the station with the highest problems using fuzzy analytic hierarchy process (AHP) and making a database based on several indicators of equipment and furniture in urban bus stations and weighting these indicators in Expert Choice software. On the other hand, prioritizing is possible by separating the problem of each station in a facility-based form for proper refer to the relevant contractors, cost management and determining the short time, medium, and long-time schedule to solve these shortcomings in these stations. Therefore, in one case study, the actual data from all bus stations of District 8 of Tehran Municipality were collected, and the mentioned method was developed for it by forming the database. The problem of cost and budget management in eliminating the shortcomings of a bus system was resolved using the findings of this research. A prioritization system based on qualitative database for stations makes possible to extend this method at the macro level in a city or country.

The objective of this study is selection of optimum repair and maintenance strategies for a group of bridges. For this purpose، influential factors on safety of users، performance and speed of bridges’ failure، were identified. Then، the weight of mentioned factors or in fact the effect of each one of these factors on the users’ safety، performance and speed of bridges’ failure was obtained by Fuzzy Verbal Method، based on experts’ ideas and through filling the relative questionnaires. At the next stage، evaluation of bridges in Mazandaran Province in terms of each one of the mentioned factors، the priority index and prioritization of bridges was determined based on their need to repair and maintenance. Ultimately، a mathematical planning model was presented and considering the budget limitation، the priority index extracted from previous stages as well as the cost and effectiveness of repair and maintenance methods specify which bridges and by which method will be remedied. This approach has been evaluated successfully by actual and simulated data.

There is a need among railway track maintenance and management for a better understanding of the railway track systems and for improved predictive techniques. Railway maintenance procedures form an integer part of expenditures in railway industries. The aim of this research is development of an appropriate system for maintenance of Iranian railway track in a management system frame work. In this context، current maintenance management systems in the USA، Europe and Asia were reviewed and 5 systems were identified (RAILER، ECOTRACK، TRACKS، RAMSYS and DTM). The research indicated that to characterize the railway and maintenance approaches in Iran، a new strategy was made in order to improve maintenance and management decision system in Iranian railway. This research identifies and classifies the best system for every characteristics such as failures، traffic and facilities، and also provides a system lines on the basis of the quality and analysis track information.

Although the current analysis and design of railway track systems are based on theassumption of continuous and linear behavior of the rail support system, repair andmaintenance plans have considerable influences on the structural behavior of thetrack support system, particularly after accumulative loading or track tamping.Recent experimental investigation indicated the behavior of the track support systemis time and stress dependent. The amount of traffic passed and the quality andquantity of maintenance activities can considerably influence the track responsefunctions. Although some experimental investigations have been carried out to studythe time and stress dependent characteristics of the ballast and subgrade materials,the effects of the consideration of these characteristics on the track analysis anddesign, need further evaluations. Furthermore, the recent extensive increases in axleloads, speed and traffic volumes in rail transport systems, require more preciseanalytical and mechanistic approaches for railway track system. This research is aresponse to this need. In this paper, the current practices in the analysis and design ofrailway track system are discussed. A mode of track support system withconsideration of discrete supports is developed. By comparison of the analysesresults obtained from track models with continuous and discrete support systems, theaccuracy of the assumption made in the Winkler model, used in the current designapproach, are evaluated. The nonlinear behaviors of the track support system werestudied and the influences made by the consideration of the non-linearity of the tracksupport system on the rail design criteria were investigated. Rail bending momentsand rail deflections as the main rail design criteria are obtained form track with alinear support and nonlinear behaviors. Obtaining large discrepancies between theresults obtained from linear and non-linear analyses, the importance of the trackregular and systematic repairs, in particular tamping and stabilizing the ballast, areproved. It is shown that the consideration of regular repairs of the track supportsystem improves the long term reliability and accuracy of the current track designapproach. Recommendations are made on the track maintenance and repairs in orderto keep the track support system in the linear conditions.