جستجوی مقالات مرتبط با کلیدواژه « s?o?i?l- f?o?u?n?d?a?t?i?o?n i?n?t?e?r?a?c?t?i?o?n » در نشریات گروه « عمران »

Rutting is one of the main sources of failure in asphalt pavements and has been widely studied because it affects safety and maintenance costs. To reduce this failure, the selection of adequate bitumen and aggregates and the proper balance between them are key elements. In this research, seven bitumen (2 base bitumen, 3 polymer-modified bitumen and 2 rubber bitumen) and asphalt mixtures with different grades (asphalt mixtures with dense grading of 19 mm and asphalt mixture with open grading of 12.5 mm) ) analyzed. The bitumens were rheologically evaluated using a dynamic shear rheometer (1DSR) and a bending beam rheometer (BBR2) to obtain high and low performance temperature 3 (PG). In addition, multiple stress creep and recovery (4MSCR) tests were performed to analyze the rutting potential of the material at different temperatures. In order to evaluate the effect of mineral skeleton on asphalt mixtures, a wheel rut test was performed. Polymer modified bitumens (5PMBs) and asphalt mixtures produced with them were the most resistant to permanent deformation with low values ​​of rut depth (2.5%). In general, open-graded mixes had better strength than dense-graded mixes. However, this comparison depends on the type of bitumen. Relationships between bitumen and mixture parameters were also proposed and they showed a good relationship between the non-recyclable creep compliance of bitumens (Jnr) and the rut depth of dense mixtures (R2 = 0.81). However, no significant relationship was found for distance-graded mixtures (R2 = 0.52).

In this study, the seismic performance of the reduced beam section (RBS) steel moment-resisting frame (SMRF) equipped with composite steel plate shear wall (CSPSW) and high-performance fiber-reinforced cementitious composites (HPFRCC) is investigated using Abaqus software. The finite element model of HPFRCC-CSPSW was validated using experimental results. Then, the seismic performance of the six-story SMRF with common SPSW, as well as HPFRCC composite CSPSW systems under near-field (NF) and far-field (FF) earthquakes, was investigated and the results (bearing capacity, stress, deformation, and energy absorption) were compared. For this purpose, 5 NF and 5 FF seismic records were used. The results showed that the energy absorption and shear capacity of HPFRCC-CSPSW increased significantly but the maximum stress value decreased compared to common SPSW. The seismic performance of the investigated systems largely depends on the type of earthquake. However, in both SPSW and HPFRCC-CSPSW systems, the maximum displacement and the base shear under the NF earthquakes were higher than those of FF earthquakes. Besides, for all NF and FF earthquakes, maximum displacement in the SPSW system occurred in lower stories, but in the frame with CSPSW, the major displacement occurred in the upper stories. The highest increase in shear capacity and energy absorption of the system in FF earthquakes was for the Tabas accelerometer (75 and 128%, respectively) and the Imperial Vali earthquake (94 and 101%, respectively). Also, the maximum displacement in SPSW and HPFRCC-CSPSW systems occurred in Northridge (14.6 cm) and Tabas (16.2 cm) NF earthquakes, respectively; the Chichi earthquake also had the greatest damage to the structure under FF earthquakes.

One of the port planning problems that has been noticed in many papers and research is the berth planning problems. Berth planning includes two sub-problems; Berth Allocation Problem (BAP) and Quay Crane Assignment Problem (QCAP). This paper develops one mathematical model by integrating these two sub-problems. The berth allocation and quay crane assignment model (BAQCAP) is solved by two metaheuristic algorithms; Taboo Search (TS) and Ant Colony Optimization (ACO). On the other hand, the berth plan is located in a disturbed environment; unexpected events may occur during the execution of the plan, making it infeasible or challenging to do the initial berth plan. These unexpected events are known as disruptions, which can impose additional costs on the port or make the initial berth plan infeasible. For this reason, The primary purpose of this paper is on the berth plan recovery in the disrupted situation. the Berth plan is recovered with two methods; Global recovery and local recovery. This paper compares global and local recovery to identify the optimal method for berth plan recovery. The numerical results show the optimal performance in the local recovery method. In this paper, the data from Shahid Rajaei port is used.

For the seismic evaluation of structures, it is required to determine the inelastic displacement ratio. Indeed, the inelastic displacement ratio is one of the most important coefficients in codes which is used in force-based design method as well as in performance-based seismic engineering (Miranda, 2000a, b). This study attempts to evaluate the inelastic displacement ratio,  for single-degree-of-freedom (SDOF) systems that is defined as follows:

The advancement of technology with an increasing population has led to the requirement for high-speed mobility trains. High-speed transportation by trains requires passing through soft soil conditions, which requires stability. High-speed trains are used nowadays in developed countries to reduce travel time. When the train moves at a critical speed, it can significantly increase the dynamic responses of the components on the railway lines. The present study examines the results of 3D numerical modeling, considering the impact of the high-speed train passing through the mechanical earth wall stabilized by plate anchors. Numerical modeling was carried out using Plaxis 3D finite element software. The impact of various factors such as the speed of the train (180, 200 & 250 Km/h), the number of plates (single, double, and triple), and the number of train tracks (1 & 2 tracks) have been investigated. The Hardening soil with small strain model has been used for modeling the behavior of the backfill soil. In this study, the geometrical characteristics of the Thalys high-speed train were used to model the train passing through the walls of 6 meters that were stabilized with plate anchors. From the results, it was concluded that Increasing train speed from 160 to 250 Km/h increases the settlement under the rails by 11% and increases the horizontal displacement of the wall by 13%. It was confirmed that increasing train speed will result in an increase in the settlement under the rails and increases the horizontal displacement of the wall in all investigated cases. Increasing the number of plates along with decreasing their dimensions has a positive effect on the wall’s performance with regard to the horizontal displacement of the wall. Also, it should be mentioned that by increasing the number of train tracks from 1 to 2, the settlement under the rails increased by 5%, and the horizontal displacement of the wall increased by 20%.

For the first time in January 1991, the issue of studies and construction of urban trains was proposed by the esteemed representatives of the city of Tabriz in the Islamic Consultative Assembly. Due to the increasing growth of intercity travel in Tabriz and the need to use a 2-rail transportation system in order to reduce traffic problems, studies of Tabriz city train lines were conducted and Tabriz city train network including 4 routes, a total of 60km and 63 stations were designed.The analysis of underground structures is very complex due to the interaction with the surrounding environment in a dynamic state. For this reason, less research has been done. One of the first people who investigated the effect of earthquakes on underground structures is Newmark, in 1968 he presented an easy method to calculate the relative strains of underground pipe structures and long tunnels (Bozorgnia et al., 1995). In 1969, Kuesel established a simple method for calculating earthquake forces on linear tunnels, which in most cases is the basic of later works. Douglas and Warshaw in 1971 presented the results of tunnel design analysis under the influence of earthquakes. Lee and Trifunac in 1979 investigated the response of the lined tunnel under the shear wave effect. In 1981, Owen and Scholl's studied three types of deformations, including compressive-tensile, longitudinal bending, and rhomboidal and elliptical deformations as the result of seismic vibrations in underground structures.

The present paper aimed to evaluate the effects of soil-structure interaction (SSI) on the seismic behavior of base-isolated geometrically irregular steel sliding structures equipped with lead rubber bearing (LRB) isolators.To this aim, the behavior of the irregular system under nonlinear time-history dynamic analysis was assessed using numerical modeling based on the finite element method in ABAQUS. The study considered various factors including irregularity, number of structure floors, soil properties, isolation, and foundation stiffness to analyze their impact on the response of the structures. 3-, 5-, and 7-story structures with 20% and 40% irregularity were modeled to investigate the effects of irregularity and the number of floors. Additionally, models of five-story structures were used to study the impacts of soil-structure interaction (SSI) on three different types of soil: soft, medium, and hard. The results of the study demonstrated that the number of floors and the structure's irregularity have a significant impact on the seismic response of the structure in terms of displacement and acceleration. As the number of floors and irregularity increase, the maximum displacement response of the structure's floors decreases. The study also highlighted the substantial influence of soil type on the seismic response of isolated structures when considering the effects of SSI. Furthermore, the findings indicated that the presence of isolators on rigid foundations had a negligible effect on the dynamic response of the structures, compared to structures without isolators.

 During the service period, concrete may come into contact with harsh environmental conditions, ultra-high performance concrete can be considered as a suitable option due to its unique strength and durability. In this study, for the first time, the effect of nanoparticles of magnesium oxide and copper oxide with amounts of 0.5, 1 and 2% separately and combined with different amounts of iron slag (2.5, 5 and 10%) on the compressive strength and electrical resistance of UHPC contains a constant content of PVA fibers in two operating modes Standard and accelerated curing (immersion in water at 95°C) were studied for different ages. Moreover, the Scanning Electron Microscopy test (SEM) is conducted on the specimens to understand the concrete's microstructure better. The results show that by using the heat treatment method and microstructure modification in the presence of new nano materials, it is possible to create a higher potential than UHPC in terms of compressive strength and electrical resistivity. So that after 90 days, the compressive strength for each of the specimens containing 1% of magnesium oxide and copper oxide nanomaterials respectively increased the compressive strength by approximately 37.4% and 37.1% compared to the 7-day sample. While the growth of the compressive strength in the accelerated mode for the mentioned specimens was 16.8% and 18.8%, respectively, compared to the standard curing. In addition, by obtaining accurate experimental relationships between the two parameters of compressive strength and electrical resistivity a non-destructive method for predicting compressive strength has been presented.

Close-range photogrammetry aims to produce accurate 3D geometric models of objects using images taken from the subject. Nowadays, the creation of realistic 3D models and their visualisation is a common practice that is becoming more popular every day. On the other hand, choosing the right modelling software for photogrammetry has always been a challenge and a topic of discussion among experts and researchers. Therefore, it is essential to examine and evaluate the models produced by different software tools. Due to the widespread use of Agisoft software among engineers and researchers in this field, this study aimed to perform image processing and modelling using two versions of this software, namely Photoscan and Metashape. In previous research, the criterion for optimising the image mesh has been based on improving the accuracy of the modelling. In order to assess and evaluate the 3D models produced by the two versions of the software, we defined different scenarios for the design of the image mesh. We compared the 3D models generated for each scenario with a mathematical reference model. We also examined the complete modelling in the software under different conditions using two different textures, as the texture of the image directly affects the quality of the point cloud. It is important to analyse the role of the image texture together with the geometry of the image mesh. Therefore, we evaluated the image texture as a radiometric index and investigated how these two factors affect the quality of the point cloud. As a result, we determined the optimal number of images with appropriate texture required to produce an accurate and high-quality 3D model.

close-range photogrammetry, we capture a series of images of an object using a specific image network. These images are then used with the Structure from Motion (SfM) method to generate point clouds and 3D models. The concept behind SfM is inspired by how our eyes perceive objects. This approach offers a quick, automated, and cost-effective way to obtain 3D data. It involves creating 3D coordinate models by processing a sequence of overlapping images of the object. Finally, the resulting 3D models are compared with a reference point cloud using the Cloud Compare point cloud processing software.

 The results of using images with simple texture show that in Photoscan software, increasing the number of images not only leads to noise in the point cloud, but also reduces the similarity of the generated model to the cube. According to the results, the best 3D model with a high similarity to the cube is associated with the fourth scenario (45 images) with an error of 0.01 millimetres. In the case of the Metashape software, the best model is associated with the third scenario (90 images) with an error of 0.05 millimetres. On the other hand, in cases where images with complex textures were used, the best point cloud is related to the fourth scenario (45 images) with an error of 0.02 millimetres in Photoscan software and to the third scenario (90 images) with an error of 0.04 millimetres in Metashape software. In general, the use of objects with complex textures leads to a better match and therefore to denser point clouds due to the presence of complex and non-uniform gradients in the images.

The results show that the optimal number of images and the presence of a complex image texture have a significant impact on the improvement of the quality of the 3D point cloud of the object. Despite the increased processing time, the quality of the 3D model does not increase significantly with a large number of images; it only leads to denser point clouds due to increased noise in the point cloud.

Considering that the issue of choosing the passenger's route and the parameters involved in it has been the focus and study of transportation planners and policymakers for decades, in this article it has been tried to increase the computational efficiency and reduce the data processing time by examining and improving the mathematical model of passenger route selection in previous studies. This issue has been addressed through multi-core data processing (parallel processing) based on the modification of mathematical models presented in previous studies in the form of a public transport dynamic assignment model with the shortest path algorithm based on the schedule and the travel elimination sub-algorithm. The results were compared with the outputs of a non-dynamic model based on the shortest link-based algorithm to measure the effect of considering the capacity constraint and dynamics of the algorithm on the calculation time and the accuracy of the output. Even though the number of calculations went up by 13.7% compared to the basic model, the time it took to solve the problem went down by 20% because of parallel processing.

Earthquakes and damages caused by corrosive environmental conditions are two important factors that threaten the desirable performance of structures in the coastal cities of the Persian Gulf in southern Iran. Taking into account both of these risks in the analysis and design of structures can reduce the loss of life and can lead to significant economic savings. In recent years, studies on the probabilistic seismic vulnerability assessment of structures have been developed. In this paper, a risk-based approach is used for seismic evaluation of reinforced concrete moment frames with medium ductility that are exposed to damage due to base-chloride corrosion of longitudinal rebars in 4 important port cities of southern Iran (including Bushehr, Assaluyeh, Bandarabbas and Chabahar). A total of 18 reinforced concrete moment frames with different number of stories and in increments of 10 years after the initiation of corrosion, were subjected to increasing dynamic analysis (IDA). Then, using the risk integral, the annual probability of collapse for frames in the studied cities was obtained and evaluated. The results of this study show that over time after the initiation of corrosion, the probability of collapse of structures increases sharply, which indicates the high need for risk-based approach to evaluate and seismic design of structures that are exposed to damages due to aggressive environments.

From long time ago, various solutions have been proposed to reduce earthquake damages, including increasing ductility and reducing structural mass. New methods are based on separating the structure from the foundation, to reduce the shear force of the base of the structure. In other words, seismic isolation is a new method for designing buildings against earthquakes, which is based on reducing the forces entering the structure due to earthquakes, instead of increasing the capacity of the structure to withstand lateral loads. This paper is a focused on the study of the effect of the placement of rubber separators with lead cores in the behavior of reinforced concrete structures under the influence of remote earthquakes. Therefore, for rubber separators with lead core in two samples of concrete structures of 3 and 5 floors, a double damping of 10 and 15% has been considered. Separating structures and fixed base structures were modeled in “Opensees” software. Afterwards, under the influence of distant earthquakes, a time history analysis was performed on them. Finally, the results of time history analysis for designs by force and direct displacement method are exposed, which include, maximum drift of floors, maximum shear of base and period of structures. Results obtained from the analysis of time history show that with the increase of the rotation time, the shear of the bases and the maximum drift in the buildings with isolators designed by direct displacement method are more than the buildings designed by force method. Buildings with separators designed by direct displacement method have sections with less capacity than buildings designed by force method.

Roadway departure crashes, especially on high-speed rural roads, tend to be severe if the roadside exposes occupants of errant vehicles to excessive injury hazard. Unforgiving roadside features, along with the lack of proper safety treatment, contribute to undesirable crash outcomes, particularly the severe injuries and frequent deaths that result from collisions between dangerous roadside elements or opposite-direction vehicles and this is important in all countries of the world. Therefore, the use of road barriers has widened during the last several years and the structural performance of road barriers can be best accessed through full-scale crash tests. Safety barriers are currently designed for different performance levels, which are set according to current CEN and MASH-NCHRP 350 performance standards. In this paper, the criteria and differences of these standards in crash testing are evaluated and examined. The results of this limited study show that although these standards are the same in the technology to perform the tests, criteria, data acquisition, and performance evaluation, these standards are too different to be used as a single standard and require the design of additional tests to resolve the dispute and their performance under in-service conditions must also be considered.

This study aims to provide a model for estimating the direct social loss incurred by communities in Iran due to the loss of life resulting from the earthquake-induced damage to infrastructure systems. Once estimated, the direct social losses caused by an earthquake can be used to quantify and analyze community resilience. Numerous past studies have focused on estimating the direct and indirect economic consequences of earthquake-induced infrastructure failure. However, a review of the relevant literature demonstrates a lack of appropriate models for calculating social costs associated with such events considering the characteristics of the subject community. Research is needed to develop suitable analytical models that quantify the social costs of earthquakes. Previous research studies have proposed using concepts like the value of a statistical life to quantify the social losses caused by hazards such as accidents, environmental pollution, and Terroristic Attacks and Fatal Diseases. Accordingly, past studies on the quantification of community seismic resilience used the value of a statistical life for countries such as the United States in conjunction with the exchange rate to arrive at costs incurred by a community due to earthquake-induced casualties. Since Iran is a country with high seismicity, underestimating the damage caused by the death of individuals and as a result, incorrect estimation of the amount of social loss incurred by the community may misguide the vulnerability reduction efforts. This will have adverse economic, political, and social consequences for the community. Several methods have been proposed to calculate the value of a statistical life, the most important of which are "Revealed Preference" and "Stated Preference." This study uses the revealed preference method to calculate the value of a statistical. This manuscript reports the methodology adopted for collecting the relevant data and the development of the model that estimates the value of a statistical life.

Risk assessment and prioritization is one of the most important components of risk management in any organization. Failure Mode and Effects Analysis (FMEA) is one of the most commonly used methods for assessment and prioritization of the multiple risks. Despite the widespread applications of this method in various industries, FMEA is associated with some shortcomings that can lead to unrealistic results. In this study, a new hybrid decision- making approach is presented in three phases to cover some of the shortcomings of the FMEA technique. In the first phase, based on the subject literature and getting help from a group of experts, 23 risks related to the construction project were identified and classified into six groups including technical, dynamics of the project environment, multiplicity of project stakeholders, employer, project management, and contractor. In the second phase, the fuzzy Stepwise Weight Assessment Ratio Analysis (SWARA) is used to measure the weights of decision criteria. In the third phase, the outputs of the previous phases are used as a basis to prioritize the risks using the Weighted Aggregated Sum Product Assessment (WASPAS) methods under fuzzy environment. To illustrate the potential benefits and applications of the proposed hybrid approach in a case study was implemented. The results obtained from the new hybrid approach to show that the low performance of the human resources, communication and cooperation of a poor contractor with another group, lack of proper management by the contractor regarding financial matters, supplier support, and subcontractors, and low performance of the human resources as the most important risks were recognized in the construction project of the Central Library of Markazi Province. Also, after performing the validation test and sensitivity analysis, it was found that the proposed method can provide valuable and effective information in helping to manage the risk of construction projects.

In high-rise reinforced concrete buildings, using base-isolating systems can increase the response of the structure. To overcome this problem, it is suggested to increase the stiffness of the building by utilizing lateral load-bearing systems such as shear walls. In the present study, the seismic response of fixed-base and lead-rubber bearing isolated dual-system reinforced concrete buildings has been compared using nonlinear time history analysis procedure according to the 2800 V4 standard and ASCE/SEI7-16 code provisions. For this purpose, 10, 15, and 20-story reinforced concrete buildings, in a similar and regular plan, with special moment frame and shear wall dual systems have been selected as a case study. A 20-story building has been considered as a tall building in this study. Results show that the response of the base-isolated structures including the mean, median, and 16% and 84% percentiles of drift ratio, floor acceleration, and base shear has a significant decrease compared to the fixed-base buildings according to the above-mentioned code provisions. Results indicate that base-isolated buildings with respect to fixe-based buildings, based on the ASCE / SEI 7-16 code compared with the 2800 V4 standard, maximum drift in the structures has a 23% more decrease and mean acceleration and base shear have an 11% more decrease. The results obtained in this study can be the basis for the development of the 2800 standard provisions to investigate the seismic response of base-isolated reinforced concrete structures at a near-fault site.

Reinforced concrete members form the main structure of a structure. The risk of corrosion of rebar is considered as an effective factor in determining the life of these structures, so identifying and investigating its destructive factors is very important, especially corrosion of longitudinal rebar; Because the weakness of concrete in tensile increases the possibility of cracking of tensile concrete and the formation of a bed to start the corrosion process in longitudinal rebar. The beginning of the corrosion process leads to a decrease in the cross-sectional area of the rebar and an increase in the corrosion products; This increase in volume due to the products causes tension around the rebar, which ultimately creates cracks in the concrete, reduces the adhesion between the concrete and the rebar, exfoliates the concrete surface and reduces the compressive strength of the concrete. Due to the fact that the adverse effects of rebar corrosion have been less studied in deep reinforced concrete beams, in this study, the corrosion effect of longitudinal rebar by applying elements such as: reduced cross section, reduced rebar yield strength, reduced concrete compressive strength, reduced adhesion The connection between concrete and rebar in ABAQUS finite element software on the stiffness and strength of deep reinforced concrete beams has been investigated. The results show that with the increasing percentage of corrosion of longitudinal rebar, the strength and stiffness of deep beams are significantly reduced so that when the longitudinal rebar reach 50% corrosion, it loses 51.38% of its strength and A reduction of 43.57% is difficult. Beam behavior has also changed from shear to bending due to corrosion and the stress-strain diagram shows the decrease in stress and strain with increasing corrosion percentage.

To reduce the damage and casualties caused by earthquakes, researchers made efforts to introduce seismic resistant structural systems. One of the new lateral force-resisting systems is the steel circular braced system called “Ogrid”. Previous studies shown the high energy dissipation and ductility of this system. This system has a high capacity to withstand nonlinear deformations after the formation of the first plastic hinge until collapse. In the present study, an attempt has been made to introduce a new type of this brace with different types of brace connection to beam and column and to evaluate its performance. For this purpose, the OGrid is used and different connections of the frame to the circular brace that embrace the connection of the brace to the beam and to the columns, as well as comparing the presence of friction and the absence of friction between the brace and the frame are modeled and the results are reviewed. It is found that by releasing the connection of the circular brace with I-shaped cross section to the column and creating friction between them with a coefficient of 0.5, the bearing capacity increases up to 22% compared to the restrained connection. In this case, before yielding, softening is observed in the proposed model, but after yielding compared to the model with restrained connection, better energy dissipation occurs due to deformations in the circular brace. Meanwhile, bearing capacity increases up to 8% by considering friction between the brace and increases up to 17% by considering friction between the brace and the column comparing with the released connections. On the other hand, the use of H-shaped circular brace with friction connection to the column and/or beam is not recommended due to the reduction of bearing capacity by at least 9% compared to the restrained connection.