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

In smart cities, with using lots of new technologies, while creating appropriate facilities in routine urban life, infrastructure problems are investigated and the necessary measures are taken in a targeted and systematic manner to solve these problems. One of the most important technologies for managing infrastructure in smart cities is IT technology. GPS and smartphone sensors are other technologies that can be widely used in these cities. Streets, roads, and pavements are important infrastructures in any city and the future smart cities. Proper supervision, repair, and improvement of pavements, streets, and urban pathways are the main factor in reducing the cost of depreciation of vehicles and providing comfort and safety for citizens. On the other hand, if timely action is taken to restore and improve the pavement, huge costs of repair and reconstruction will be avoided, and this can significantly reduce the costs of urban management. The first step to achieving this goal is to identify the location of the roughness and distortion of the surface of the streets and urban pathways and the severity of these failures in the shortest possible time. In this paper, road surface roughnesses and failures have been studied using accelerometer sensors and GPS smartphone devices. Location and vertical acceleration data have been entered into GIS software and a quantitative index based on the values of vertical acceleration has been introduced to determine the quality of each section of urban road pavement. In this research, Androsensor software, which is a useful application for using smartphone sensors, has been used. This software is installed on two smartphones, Huawei, P30 Lite, and BlackBerry, Priv STV100. To collect the data, the smartphones were placed in a fixed position on the right and left sides of the car, on the dashboard. The collected data for analysis is transferred to the computer in Excel files. This research has been done in Kerman city and to collect data, different routes with specific failures have been selected. Data collection was performed in 81 pieces with a length of 500 meters and 24 pieces with a length of 200 meters (105 pieces, 45300 meters in total). By analyzing the vertical acceleration data and calculating some proposed indexes and comparing them, the best index has been selected. This index is classified into different ranges according to the field inspection of the pavement condition in the routes in this study, that each of which indicates the quality status of the pavement. Each of these intervals is introduced with a specific color, and by examining the index obtained in each route and the corresponding interval, the studied routes are marked with different colors on the map. Finally, it was found that the accelerometer sensors and GPS of smartphones can be used with low cost, high speed, and appropriate accuracy to check the surface of pavement of urban roads and grading the quality of the pavement. It also seems that in the smart cities of the future, which are based on IT technology, the use of user data, high accuracy in locating, and speed of action in prevention, the proposed method in this research can be used more favorably.

The pumping phenomenon is one of the major causes of damage in concrete pavements of roads and airports. To reduce the effects of pumping, this paper proposes attaching to the pavement slab a structural element of the same material that is oriented perpendicular to the pavement plane. The study investigated the effect of this structural element on the vertical deformation of the concrete pavement, especially around the edge of the slab, and the horizontal displacement of the fine fraction of saturated soil (base or bed) beneath the slab near the joints. Stress and deformation analyses were performed by modeling the slab-soil system under static and dynamic traffic loads in ABAQUS software. Stress and deformation analyses of the slab with and without the attachment (the element placed perpendicular to the slab plane) showed the positive effect of the element on the vertical deformation of the slab and also the deformation of the soil underneath the slab parallel and perpendicular to the direction of traffic. The edge displacement in the simple slab and the one with the attachment was determined to be 1.5 and 0.98, respectively. The highest vertical displacements in the modeled concrete slabs were observed in the simple slab under static loading (0.42) followed by the modified slab under static loading (0.3). The software outputs also showed the positive effect of the element on the stress in the concrete pavement slab and the soil beneath it.

With the expansion of cities and the emergence of various industries and changing uses for appropriate development, the need to use the network of asphalt roads has increased day by day and it has also occurred. This is clearly visible in industrial cities and the management of the pavement system in these cities should be such that the network monitors the inner city roads well and prevents the reduction of pavement quality in terms of service and safety to users. . The city of Bandar Mahshahr, as a center and base of petrochemicals in Iran, which has accommodated huge petrochemical industries, etc., has a wide network of roads that have a wide role in supplying and delivering industrial parts to this city. This opinion helps to improve the condition of the pavement in this city by continuously examining the pavement and identifying the defects in the road surface. if it

Structures are subjected to different kinds of loads during their lifetime, such as those caused by daily temperature swings, traffic loads, abrasion and severe loads like earthquake.  The occurrence of damage in building structures, oil platforms, and generally all structural systems is inevitable. Different kinds of failure in various engineering structures have been observed so far, which have incurred massive financial losses and serious casualties. Most of such damages could be identified with structural condition assessment, and therefore crack propagation in and total collapse of the structure can be prevented by taking rehabilitation measures. The fact that in seismic prone regions where the occurrence of minor and local damages could lead to the total collapse of the structure increases the importance of structural health monitoring substantially. Hence, determining the damages in structures in order to monitor structural health, increase the safety of the structure, and determining the current condition of the structure seems vital. In this research, spectral strain energy is considered as an index for determining the location of the damage. By making a comparison between the spectral strain energy of healthy structure and damaged structure, damaged elements can be identified. In addition, the capability of the aforementioned method in the linear and nonlinear regimes will be assessed. To demonstrate the efficiency of the adopted procedure, numerical examples are provided whose results indicate precision and suitable performance of the proposed method in identifying damages in structures.

Road maintenance is considered as one of the major and important factors in the pavement management system (PMS). Regarding the type of data collection in this study, the observation method based on index PCI (Pavement Condition Index) according to ASTM D6433 standard was used. Research aims to assess the priority of road maintenance using the Pavement Condition Index (PCI). Locations for this research were the roads at the EMU campus to length 10 km in Northern Cyprus and 16 road segments were taken from each district. There were 9 distress types that had been recorded. We intend to add to this project a new dimension by analyzing the EMU campus road. The results of the research as obtained from the method of PCI and prioritization can be identified as follows: five road segments are in good condition, four are satisfactory, six are in fair condition, one is in a failed condition, and one road segment is in serious condition. In total, 15 of 16 road segments are in stable condition. The result generally indicates that the road was 80.63% in satisfactory condition. In general, it can be concluded that road pavements are constantly exposed to various types of stresses such as heavy traffic load, temperature, humidity and bed soil displacement, which over time lead to damage such as cracks in the Alligator cracking, Patching and Utility cut, Block cracking, Long and Trans cracking, Rutting, and Asphalt Bleeding are in the pavement. Patching and Utility cut, Alligator cracking and Long and Trans cracking were assessed as the most severe.

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.

One of the most important goals of a pavement management system is determination of optimal priorities and time for repairs, through prediction of pavement status. In fact, the purpose of the PMS system is to repair and maintain the early stages of cost savings and savings. . Therefore, in this study, in order to determine the Pavement Condition Index (PCI), two linear regression models and back propagation neural network models were fitted and their power estimates were compared.  In this regard, the damages of three freeways of Karbala, Paul Zal and Tehran - Qom have been studied to identify the appropriate method for predicting pavement status index in order to identify the optimal maintenance time to reduce its costs. . Micropaver software and MATLAB and SPSS software were used for modeling and evaluation of components. This track was sampled in order to capture the failure of sample units at 100 m intervals and parts at 500 m intervals. The variables considered in the model analysis included: segment lifetime at inspection time (month), unit width, average AADT at segment lifetime, average percentage of heavy vehicles at segment lifetime, maximum temperature at segment lifetime in 1396, minimum Temperature is the lifetime of the piece in 1396 and the thickness of the pavement (cm). . The results show that the performance of neural network model based on mean square error index (MSE) as well as R2 index is 0.95 and 0.87, respectively, which is more valid than the multiple linear regression model (0.139). The future is paved. In addition, according to the neural network model, the lifetime of the segment can be most important in neural network construction (0.55) and then maximum temperature (0.122) and percentage of heavy vehicles (0.120) are the next important variables in predicting pavement status of roads.

The past severe earthquakes around the world have shown that the beam to column connection is prone to failure. Therefore, significant provisions should be considered in the design of the connection. RCS moment-resisting frame systems, consisting of Reinforced Concrete (RC) columns and Steel (S) beams, take advantage of the inherent stiffness and damping, as well as low-cost of concrete, the lightweight and construction efficiency of structural steel. Since two types of materials including steel and concrete are used in a RCS system, the detail of the connection plays a significant role on the overall performance of the system. In general, there are two types of RCS connections, column through type & beam through type. The main objective of this study is to investigate the effect of parallel and diagonal stiffeners on stress-strain propagation and concrete damage in column through type RCS connections. For this purpose, RCS connections with different joint details were modeled and analyzed in ABAQUS. Finite element analyses results showed that parallel stiffeners are more capable to provide confinement in comparison to the diagonal types. However, the performance of diagonal stiffeners in terms of strength and plastic hinge formation in the joint is better than parallel stiffeners. Increase of stiffener thickness causes to improve the performance of joint core and decreases its damage level. Furthermore, increasing in cover-plate thickness improves the performance of connections in terms of of strength and plastic hinge formation.

It is realized that the economy of many littoral countries, including Iran, is dependent on the marine developments; therefore, the construction of port structures as the point of berthing, mooring, and repair of marine vessels has boomed in recent years. Hence, there has been significant research on the design of port and harbor structures, which leads to the development of performance-based design method as a highly reliable way for seismic design of these structures. Seismic actions may cause uncontrolled damages to wharves and piers, resulting in huge economic losses to the country. Iran is also one of the most seismically active zones and contrary to the seismic design of waterfront structures which still leaves much to the designer’s judgment, there are several published codes for performance-based design of building structures. So in this paper, the state-of-the-art ASCE/COPRI 61-14 code requirements on seismic design of wharves and piers has been studied along with the performance-based design method.

Fluid storage tanks, especially above ground tanks, are categorized as important and essential in energy infrastructure. These storages, which are mostly used to store petroleum fluids and fire water supplies, are therefore of great importance to the exploitation of tanks after the earthquakes. Fragility or vulnerability curve is one of the most effective tools for estimating the damage caused by the earthquake. Preparing the seismic fragility curve of above ground tanks on a pile is the aim of this research. This fragility curve is achieved regardless of tank body damage and only by focusing on the structural behavior of the foundation. These tank types are primarily built on low load bearing areas. In this study, three tank types that have been designed in accordance with API650-13 have been investigated in a practical project. For this purpose, using the static nonlinear analysis method, the structural capacitance curve of tanks was first obtained. Then, the seismic performance of these tanks was obtained for 12 spectra from different records with different accelerations. After calculating the damage indexes on the structure, the appropriate statistical distribution for the failure criteria was chosen. Finally, the calculation of the probability of failure for the fracture curve of the required tanks was obtained Fluid storage tanks, especially above ground tanks, are categorized as important and essential in energy infrastructure. These storages, which are mostly used to store petroleum fluids and fire water supplies, are therefore of great importance to the exploitation of tanks after the earthquakes. Fragility or vulnerability curve is one of the most effective tools for estimating the damage caused by the earthquake. Preparing the seismic fragility curve of above ground tanks on a pile is the aim of this research. This fragility curve is achieved regardless of tank body damage and only by focusing on the structural behavior of the foundation. These tank types are primarily built on low load bearing areas. In this study, three tank types that have been designed in accordance with API650-13 have been investigated in a practical project. For this purpose, using the static nonlinear analysis method, the structural capacitance curve of tanks was first obtained. Then, the seismic performance of these tanks was obtained for 12 spectra from different records with different accelerations. After calculating the damage indexes on the structure, the appropriate statistical distribution for the failure criteria was chosen. Finally, the calculation of the probability of failure for the fracture curve of the required tanks was obtained.

All bridges designed by kind of structure and built by any type of materials, get burnt out sooner or later. These exhaustions are spread due to several factors such as atmospheric conditions, flood or earthquakes, increased over load more than expected in design phase, design and execution quality, and the type of materials affecting that causes to decrease bridge's useful life if these factors will be ignored. Therefore, bridge maintenance makes to increase its useful life if it happens on time. In this paper, Mazandaran province bridges are studied based on failure situation, faults of each bridges, their condition against traffic load and other effective variables.in order to solve the problem, first, required data have been collected by field study after bridges inspection and then bridges are prioritized based on fault evaluation criteria by Analytic Hierarchy Process (AHP) multi attribute decision making method. Finally, corrective actions are determined based on budget level for bridges. To achieve this goal, a linear mathematical programming model firstly presented and then to solve the large scale problem a genetic algorithm has been developed to find the optimal corrective actions. The proposed algorithm is implemented in MATLAB software and results show that the proposed genetic algorithm have suitable performance to solve the problem. Several budget levels have been considered to assess proposed genetic algorithm validation and changing trend of corrective actions number has been studied. It is seen that amount of effectiveness and total number of repairs are increased by soaring budget level

Roads and pavements are one of the most important assets in any country and considerable amount of money is paid for their rehabilitation or maintenance annually. Pavement surface is the most expensive and susceptible layer as it is in direct contact with traffic and also it experiences different environmental conditions during different seasons. Harsh weather condition and winter maintenance is another parameter that can increase the annual maintenance cost significantly. Winter snow and the resulting ice, can reduce pavement surface friction and therefore, deicing material such as deicing salt or calcium acetate are used to melt the ice and snow. Deicing material decrease the frost temperature and melt the remaining ice and snow and the resulting water flows due to the longitudinal and transverse grade over the pavement surface. The flowing water goes through longer distances in locations were the drainage system is not adequate.
Although several researchers and scientists have studied the effects of deicing material on asphalt and concrete pavement deterioration, but what has not been fully studied is the simultaneous effects of deicing material and water flow on the rate of pavement deterioration under freeze-thaw cycles. Therefore, the focus of this study is to evaluate the combined effects of flowing water and deicing material on the deterioration of asphalt pavements under freeze-thaw cycles. Two types of asphalt samples were prepared and subjected to five different freeze-thaw exposure conditions. Deicing salt and calcium acetate were used as the deicing material in this study. The samples were also tested in an abrasion test apparatus and subjected to normal and frictional forces. This abrasion test apparatus was built based on the concepts used in Hamburg Wheel-Tracking Device. Marshall strength loss and weight loss of the samples were measured and used as a measure of asphalt deterioration.
Results showed that the combined effects of water flow and deicers increases the deterioration of asphalt concrete samples under freeze–thaw conditions. Furthermore, deicing salt has more deteriorative effects on asphalt concrete in comparison to calcium acetate. In addition, results indicated the water flow has significant effects on asphalt concrete pavement stripping and strength loss. Water flow slows down the formation of ice during freezing cycles by not allowing or slowing the formation of ice crystals and their agglomeration. In still plain water freeze-thaw chamber, a thin ice layer was formed in zero degrees of centigrade and its depth increased during the freezing cycles but in the flowing plain water freezing condition, where the water flow was present, small ice particles started to form in areas in the chamber where the water flow was in its lowest level. Then, the ice formation gradually expanded to the area with the highest level of water flow. Besides the mentioned effects of water flow, the presence of water flow decreases the freezing temperature of water in the asphalt concrete pores and, consequently, the hydrostatic pressure inside the asphalt concrete increases significantly. Therefore, the asphalt concrete deterioration process becomes faster and more severe when water flow is present in the freeze-thaw cycles.

If layout of underground storage of energetic materials such as explosives¡ gases and petroleum designed inappropriately¡ an unexpected explosion can result in transmission and spread of the explosion to other adjacent underground spaces and causing catastrophic events both in surface and underground. In this paper a calibrated elasto-plastic numerical model in FLAC3D software is used to simulate the underground storage explosion. The peak particle velocity (PPV) damage criterion and the plastic deformation criterion were adopted to study the extent of damage zone around the explosion. The results show that the extent of damage measured based on the PPV criterion is larger than the plastic deformation criterion. Investigating responses of concrete lining supports shows tensile ruptures in the concrete due to reflection of stress waves from inner walls¡ which can cause transmission of explosion without direct contact of damage zone to the nearby storage chamber. Finally¡ in this paper the safe separation distance and embedment depth is proposed for three underground explosives storage chambers of Bakhtiari Dam project.
Summary: In this paper¡ the explosion of underground storage facilities are modeled numerically using Flac3D software and it is tried to find the optimum layout of the underground facilities based on the extension of the explosion damage zone in numerical simulations.
The main purpose of this research is the use of numerical modeling in prediction of safe separation distance and embedment depth for energetic materials underground storage chambers¡ to prevent transmission of explosion between chambers.
Methodology and Approaches: In this paper¡ major features of chambers and surrounding rock mass have been numerically simulated using 3D finite difference method. The damage extension around the exploded chamber is evaluated using two criteria of critical PPV and Mohr-Coulomb failure criterion. The results of numerical simulations are compared with international standards.
Results and The results have proved that due to explosion stress waves reflection from inner walls of adjacent chambers that causes tensional cracks in concrete supports and adjacent rock mass it is necessary to simulate the presence of adjacent chambers in the numerical models. Results of simulations in different rock masses show that in strong rock masses¡ the extension of the damage zone is lower than week rocks¡ while due to lower attenuating ability of strong rock masses¡ the energy of stress waves propagating with in it is high and vice versa.

Building structures begin to deteriorate once they are built due to harsh environment such as earthquake. To inspect present buildings and bridges following major disastrous events, such as earthquakes and hurricanes is often time-consuming and of high expense. This is also the case in regular operating conditions. Indeed critical members and connections are hidden under cladding and other architectural surface covers. This study aims to propose a novel method for identification of damages occurred in beams based on deflection under static loading. In this paper damage location on a beam is determined using statistical hypothesis testing applied on the deflection of the beam. It is worth mentioning that the statistical hypothesis testing is an appropriate method for statistical inference which can be used to judge a claim concerning an event in regards to different scenarios and possibilities. The statistical claim which would be analyzed is that damage is present among elements of the beam. Deflection of beam as a derivation of stiffness will be utilized here. Hence the basic idea in this study; to locate damages, is behind of calculating the difference between measured and estimated deflection of nodes of each element in both intact and damaged structures. Elements damage can be specified by applying damage index which is defined as D(x). Element’s damages can be judged through the damage index sign in two nodes of every element: The element will be considered damaged if the index is positive for both nodes of middle element or it is positive in only one node of element leading edges of fulcrums.To illustrate the efficiency and robustness of proposed method three different examples are considered. First example is a simple beam with five different scenarios including single and multiple damages. Second example is also presented to show comparison of the proposed method with the study by Abdo [18] and finally third instant is considered for showing reliability of the method in different beam types. For all of the examples, the deflection of damaged beams is recorded via sensors under only one state of static loading and the statistical parameters of the undamaged beams are generated under several static loading. Then by calculation of damage index, we can decide about damage locations. All examples show good performance of the novel method in damage localization. The most important result obtained from these examples is that, the more fine mesh, the better and the more accurate performance of the method. Of course this assertion is more important in the elements leading edges of fulcrums.Further, the performance of this method is demonstrated through damage simulation where the measured data are contaminated with noise and hence to evaluate the stability of the proposed method against various noise levels, scenarios are considered with different such levels.

The pavement management system (PMS) is a synchronous and regular procedure to conduct all of the works related to the pavement maintenance and repair. Through a proper PMS، sustainable and correct decisions in maintenance، repair and rehabilitation of pavements are possible. Pavement management is proceeded at two levels: Project level and Network level. Pavement management at project level copes with detailed design decisions for each project separately and at network level it copes with building a priority and schedule program for construction، maintenance and rehabilitation of a new pavement along with budget limitations. PMS software input includes 3 types of data: road inventory، pavement situation and maintenance and repair strategies and their costs. The aim of gathering pavement deterioration data and their reasons is identification of the situation for each road section based on the scale of pavement deterioration. The next step is classification of pavements based on the scale of pavement deterioration. The PMS software identifies the potential repair options for each section and estimates the repair costs and then prioritizes and determines the most economic methods of maintenance and repair. Finally، it represents the result of data analysis as a detailed report including prioritized maintenance options for each section along with their costs.

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.

The objective of all the flexible pavements design methods is that the designed pavement should sustain effective factors. Inter alia, the important effective factors include pavement conditions and states. The designed pavement plays two significant roles in relation with stresses and deformations. Stresses should decrease to such a level that firstly, they are tolerable for the subgrade and secondly, they cause no structural damage in the pavement. In order to actualize this, all the effective ideas should be utilized and effective parameters should be identified and carefully assessed. In this paper, the flexible pavement structure has been modeled using the finite element Abacus software and the effect of tire diameter variations on stresses and strains are studied. This pavement was under a load having circular section and a magnitude of 4.5 ton. Four different diameters were selected for the loading surface and four important parameters having the most effect in coasing defect in the flexible pavements were inspected. Due to the analysis of the models, it was observed that the response of the pavement to each loading surface was different.