نشریه مهندسی عمران
سال پنجاه و چهارم شماره 9 (آذر 1401)

The process of biomineralization as a method of biological soil improvement refers to a set of biochemical reactions in which the sediment formed by bacteria causes the grains of soil to graft and thus improve its properties. In the present study, after optimizing the precipitation conditions, the effect of the sample making method on the biological improvement of Kermanshah clay fine-grained soil with two bacteria Bacillus megaterium and Lysinibacillus boronitolerans was studied. The results show that the method of sample making (in terms of adding biocementation solutions) has a significant effect on the improvement of compressive strength of samples. The maximum improvement of soil compressive strength (up to 2.68) occurred for Bacillus megaterium in adsorption method. In general, the addition of solution to the soil by adsorption method has been more effective in the proper placement of sediment between soil grains than the mixing and injection method. It has been more effective and in fact the solutions have been allowed to move between the soil grains to the corners where the grains join, thus resulting in the formation of effective sediment at the grains joint. Also, biological stabilization of the consolidation test sample reduced the soil void ratio change from 0.584 to 0.354 and the compression index from 0.077 to 0.038. The addition of biocementation solutions to the sample of atterberg limits test sample reduced the plasticity index from 26 to 19.

Because of the impact of void ratio parameter on liquefaction and static strength of sandy soils, preparation of samples which are homogenous in their heights in monotonic and cyclic triaxial tests is an important issue. Undercompaction method is an extended preparation method of wet tamping that is a suitable procedure to make homogenous sandy soil with fines. In this research, undercompaction method is used in order to prepare samples of carbonated silty sand from Boushehr Port and a method called injection of gelatin solution is used to control the homogeneity of samples. In order to investigate the effect of silt content on homogeneity of prepared samples, Boushehr carbonated sand is mixed with silt percent of 0 to 40%, and gelatin solution is injected in the samples. Results show that samples prepared with undercompaction method are homogenous, also variation of silt content, changes the parameter of reduced compation percent of first layer (Un). In silt percent 0 to 20%, Un parameter limited to 4 and 6%, and in silt percent of 30 to 40%, Un parameter is obtained 6 and 8%. It can be concluded that in lesser percent of silt, intergranular voids of sandy soil are filled with silt particles, thus first layer is compacted close to the desired density, and the final compacted sample is more homogenous than the samples with higher percent of silt.

In this research, a numerical study has been performed on the seismic behavior of the deficient RC beam-column joints (with non-seismic detailing), and the seismic rehabilitation of these joints by using FRP composite laminates. At first, based on previous experimental studies, a series of RC joint specimen were considered to verification the proposed numerical model. These series of specimens include six RC interior joint specimens with non-seismic detailing and retrofitted with FRP laminates under cyclic loading. Comparison between the load-displacement curves obtained from numerical model with corresponding experimental data show that the proposed model is capable to high accurately predict the response of RC joints under cyclic loading. Then, based on the verified model, the performance of two dimensional (2-D) deficient and strengthened exterior RC joint, three dimensional (3-D) interior and exterior RC joints with considering the effect of slab and beam perpendicular to the plane of frame and also strengthening of (3-D) RC joints with focusing on the behavior of the FRP to concrete interface is evaluated. It was observed that the failure mode of the retrofitted RC exterior specimens, unlike the deficient specimens, is the formation of the plastic hinge in the beam section. In addition, it is seen that the slab and the lateral beam have a significant effect on the performance of deficient joints, which can increase the resistance of the 3-D specimens by more than 20%; also, in 3D strengthened joints, the possibility debonding of FRP laminates from concrete is higher than the 2-D model.

Damage detection in structures has received much attention, especially in recent years. Due to the importance of bridges, the identification of damage in this type of structure is very significant. In this research, a new method for identifying damage in concrete girders of bridge decks is presented. Ease of use, high accuracy, and reduction of monitoring costs have been considered defaults for presenting the new method. In this research, using signal processing tools and artificial intelligence, damage-sensitive features have been extracted in such a way that the damage with its severity and location is determined with very high accuracy (about 99%) and error percentage less than 1. In fact, damage can be detected with such accuracy only by using vibration response signals received from a sensor. According to the proposed method, the response signals received from the structure in healthy and damaged conditions are processed using the time-frequency function. Then the processing results are defined as inputs to the neural network, and the appropriate outputs are determined. In other words, the neural network is trained. To evaluate, validate and ensure the performance of the method, the numerical model of concrete beams and the numerical model of Shahid Madani Bridge in Tabriz in normal and noisy conditions have been used. The results of the calculations show the high diagnostic accuracy of this method and the least amount of error in determining the health of the structure as well as identifying the location of the damaged element.

Considering the role of water in the socio-economic development of countries as well as the quantitative and qualitative problems of water resources that cause crises, it is necessary to take a comprehensive approach in this field. Accordingly, the use of integrated water resources management in planning and policy-making of water resources has been considered. Water accounting is used to provide an integrated assessment of water resources by provision of needed data set. Among the various water accounting frameworks, the system of environmental-economic accounting for water is a suitable tool that, with its information system and support for integrated water resources management, can help policy-makers to make informed decisions in various fields, such as water allocation, improving water efficiency, and so on. In this study, by using the mentioned framework, water accounts related to Hashtgerd study area in 2006 and 2016 were compiled. Then, by production of water resources, economic and social indicators, the assessment of water resources system in the area has been conducted. The results indicate the critical status of water resources in the study area in such a way that the agricultural sector with 95.5% of water consumption has the greatest impact on the high values of relative water stress and water consumption intensity and although water consumption has increased, economic water productivity in this sector has declined. In addition, despite the state of water scarcity and the low per capita amount of renewable water resources, water consumption is still increasing.

Evaluating the vulnerability of bridges to flooding is essential for risk-informed planning of their maintenance. This paper aims to develop a systematic model for investigating the behavior of bridges at the time of flooding, in which structural, geotechnical, and hydraulic parameters are considered. A three-dimensional finite element model of reinforced concrete bridge piers was developed, in which the material nonlinearity and the interactions between the pier and the surrounding soil and the flood water were considered. The parameters used in the model were validated based on experimental data from a single pile and a reinforced concrete column under axial and lateral loading. The validated modeling approach was then used to simulate an existing bridge pier, for which the structural, geotechnical, and hydraulic parameters were varied to evaluate the effective parameters. The results showed that the presented modeling approach is capable of providing reliable predictions of the performance of bridge piers at the time of flooding, which makes it suitable for practical vulnerability assessment of bridges. Moreover, it was observed that the behavior of the bridge piers against floods was more sensitive to geotechnical and hydraulic parameters than structural parameters, to the level that by changing the soil type from medium sand to loose sand, the lateral displacement of the structure is 1.87 times. Also, by increasing the longitudinal slope from 0.004 to 0.005 and decreasing the roughness coefficient from 0.025 to 0.021, the lateral displacement of the structure will change to 2.57 and 6.55 times its initial value, respectively.

One of the most widely used structural systems in existing buildings are reinforced concrete moment resisting frames that offer high ductility and acceptable strength when lateral loads are applied. In the present paper, a laboratory and numerical study of the effect of using non-uniform gap (NSD) dampers in concrete frames has been performed. In the present study, 2 models including a simple frame and a frame with a damper were examined. The reference concrete flexural frame is modeled in a 1: 3 scale, the lengths of beams and columns in the laboratory sample were 1.45 and 1 m, respectively, and the dimensions of beam and column sections were 150 by 150 mm. Reinforcement of the concrete frame was done in such a way as to provide medium torque resistance conditions in the frame. Displacement control loading was used. To study the behavior of the studied samples, force-displacement diagrams of the models were extracted. The results showed that deep cracks were created at the junction of the beam to the column and the structure was damaged. Also, at the junction of the column with the foundation of the structure, it has undergone irreversible deformations and major damage. The study of the effect of NSD damper on deformation and failure showed that the damper can reduce the damage in the concrete frame by absorbing permanent deformation. The results showed that the stresses and deformations of the plastic are concentrated in the damper and the frame performance is almost linear and without damage.

Timely delivery of materials and equipment to the floors of a high-rise construction project is one of the main challenges for project managers. To solve this challenge, tools such as lifts and cranes are used to transport materials vertically. For the reasons explained in the text of the article, the lift is a more suitable option for the vertical movement of materials in high-rise buildings. The way the lift moves between the floors of the building and the amount of material moved by the lift in each round directly affect the completion time of the project. Therefore, providing an optimal schedule for vertical transportation of materials in a high-rise project can lead to proper use of time and prevent delays in the project. In this paper, a mathematical model with the priority of activity in the day shift and also meeting the maximum amount of demand in two consecutive shifts, to minimize the time of lifting activity is presented.The proposed model tries to meet the demand of the classes as much as possible, and if the demand is so high that it is not possible to meet the demand during two consecutive shifts, considering the fine, it gives the best way to move the lift. Finally, the proposed method is validated on a real data sample related to a high-rise project. The proposed model, in addition to examining the actual sample compared to the models introduced in similar studies, provides an optimal material handling schedule for each work shift.

One of the methods to improve the properties of asphalt mixtures is using additives. One of the additives that have received a lot of attention in recent years is nanomaterials, which have been very popular due to their unique characteristics. In this study, the effects of nanographene on the performance characteristics of hot asphalt mixtures have been investigated. For this purpose, bitumen was modified in 0.1%, 0.3%, and 0.5% (by weight of bitumen) and by performing bitumen tests, the optimal amount of nanographene selected was 0.5%. Then, in order to evaluate the performance characteristics of the mixtures, repeated axial load tests (RLA), indirect tensile strength modulus (ITSM), and indirect tensile fatigue test (ITF) were performed. Besides, in order to evaluate the moisture sensitivity of the mixtures, indirect and compressive tensile tests were performed on the samples in both dry and wet conditions. The results showed a decrease in the final deformation, an increase in stiffness at temperatures of 5, 25, and 40 by 15, 36, and 54%, respectively. Also, in some samples, the fatigue life of modified asphalt mixtures was improved by up to 55% compared to conventional mixtures. Increasing the TSR index in the indirect tensile test indicates an improvement in the performance of the modified sample compared to conventional samples and a decrease in their sensitivity against moisture, to the extent that the indirect tensile strength of the modified sample in dry and wet conditions compared to conventional samples Increased by 23% and 38% respectively.

The increasing demand for private cars and the unbalanced and dense growth of land-uses in the north of Tehran metropolis have caused fuel supply stations (gas stations) to always face the demand queue. On the other hand, the exorbitant price of land in these areas does not make the construction of a new location cost-effective. Demand management policies such as increasing the cost of using the facility are the possible solution to solve such problems. In this paper, the gas station users' data in the north of Tehran were collected using the stated preference method and analyzed using SPSS statistical analysis software to define the agent features and build agent-based modeling. The survey results were used to define the characteristics of factors and interactive rules in NetLogo simulation software. Then, the existence of a fast-passing line (with five different pricing scenarios) was simulated compared to the normal condition. The results showed that although the price increase scenarios (scenarios 4 and 5) are more welcome by relying on the statistically-based stated preference method, the agent-based simulation shows the popularity of cheap scenarios (scenarios 1 and 2) based on the interactive behavior of people are more valid. This indicates that the stated preference method's responses cannot be reassured in cases where interactive behaviors exist. Also, due to the imbalance of supply and demand due to the region's context, creating a tolled high-speed passing line is an effective solution to adjust the queue length and reduce waiting time.

Due to the importance of coastal structures and the existence of destructive environmental conditions near the shores, the maintenance of these structures is more important. One of the ways to maintain such structures is to apply a protective coating layer of mortar. In recent years, due to the importance of environmental impacts and also in order to reduce energy consumption, geopolymer mortars have been considered as an appropriate alternative. Geopolymers are inorganic aluminosilicate compounds in which instead of cement, a matrix of aluminosilicate materials, which is activated by alkaline activators, plays the role of cement paste in the mortar.In this research, mechanical properties and durability of 6 mortar mix designs, including 4 cement-based mortar mixtures containing supplementary cementitious materials and 2 geopolymer mortar combinations with slag and silica fume that cured in the simulated Persian Gulf environment has been compared. To compare the mechanical properties, compressive strength, tensile strength, and drying shrinkage tests were conducted. Also, the capillary water absorption, water penetration under pressure, and rapid chloride migration tests are performed to evaluate the durability.The results of this study display that ternary cement-based mortar that has higher amounts of SCMs is a better choice than binary cement-based mortars and geopolymer repair mortars for repairing damaged concrete structures in coastal areas. Among other mixtures, the geopolymer mixture with potassium hydroxide as an alkaline activator and the cement-based mixture with a replacement of 7.5% by weight of silica fume can be introduced as suitable materials for repairing marine structures.

In the field of buried or underground structures, passive defense is in fact the same effort to design, improve and place these types of structures properly. Numerical and computer modeling is one of the best methods that can be used to analyze problems. In this research, using the previous results, the accuracy of surface explosion loading modeling results has been evaluated, and after ensuring this modeling, the structures buried in different soils and the layered system have been investigated. In modeling the effect of soil-structure interaction is considered and the analysis is performed non-linearly using Abacus software. The structure is buried in the soil as a single layer, two layers and three layers with a burial depth of 8 meters above the ground and a comparison of displacement and stress is discussed. The soils used in this research are soft sand, hard sand and clay. The results show that the highest displacement is related to the conditions of placement of the first layer of soft sand, the second layer of hard sand and the third layer of clay, and the lowest amount of displacement is related to the conditions one layer of soft sandy soil. Also, changes in the material and number of layers sometimes lead to a reduction of up to 100% in the resulting stresses and up to 19% in the displacement in the buried structure. This issue shows the necessity of the effect of soil layering in the design of buried structures.

Seismic codes are a pioneer in providing seismic criteria in the nonlinear behavior of structures, but usually less attention is paid to the two main phenomena. The first is the phenomenon of impact of adjacent structures, which can cause severe nonlinear behaviors, and regulations usually suggest a discontinuous joint between two structures to prevent its effects on adjacent structures, but if necessary, the impact of pounding with a discontinuous joint is investigated. Or implemented, no proposal is presented, and the second is the effects of seismic sequencing. In this paper, in order to investigate the impact of adjacent steel moment structures due to successive earthquakes near and far fault, six pairs of steel frames with different heights, with and without height difference on the ground floor have been used. These frames have been evaluated using nonlinear time history analysis under the effect of 24 consecutive earthquakes in the near and far faults in the form of three sequential seismic composition scales that have been scaled according to the fourth edition of the 2800 standard. The results of the study showed that the joint seam did not prevent adjacent frames from colliding with each other and needed to be reviewed, but compared to the frames in contact, which in most cases hit the frames together led to the collapse of the structure, is more appropriate and reduces damage. Impact force changes the behavior of adjacent colliding frames relative to the expected behaviors of the frames without impact and exhibits different responses.

The effective simulation of collision between two adjacent structures has always been of interest in structural engineering. Several analytical models have been proposed by different scholars to simulate this phenomenon. The Kelvin-Voigt Model is one of the popular ones due to its linearity, and ease of application. In this study, a parameter (coefficient α) is introduced in the original Kelvin-Voigt Model to calculate the energy dissipation both in compression and restitution (separation) phases of the contact. Besides, the accuracy of the modified model has been improved by presenting a new equation for the estimation of damped energy. Furthermore, the tensile force is eliminated in the restitution phase. The effectiveness of the proposed modified model in the simulation of the collision was examined by comparing the results with those of the original model, as well as previous experimental studies. The mean relative error between the selected coefficient of restitution before the collision and the coefficient of restitution after the collision that was evaluated by different models were compared. The modified model proposed in this study showed the least error values among all of the other models. This indicated the ability of the model to estimate the damped energy with better accuracy. The results of this research study indicate that the proposed modified Kelvin-Voight Model is effective in the simulation of collision between two structures.

The vulnerability of industrial plants to natural hazards has made world worries because of countries general disability about the prediction of the level of effects and preparedness for the consequences of these types of events. For this purpose, seismic assessment of plant equipment is a strategic issue. One of the most equipment that is used in most oil & gas plants is stack flares. Stack flares are a type of stacks that are used for burning additional flammable gases before causing any other problem for other plant facilities. Proper seismic assessment of this type of equipment has been missed in the past and its exact performance evaluation can be effective in determining probable damages in future earthquakes and distinguishing the weakness of components of this type of structure. In this study probabilistic seismic behavior of two designed and constructed stack flares are investigated and using incremental dynamic analysis their fragility curve and behavior factor are calculated. Results show that in ordinary intensities, the seismic demand of these structures is not considerable but in range of rare intensities, extreme damages are probable. Also, in the above case studies, the performance of 4 side stack with respect to 3 side stack was more proper, and seems more assessment is needed on the suggested behavior factor by codes.

The main purpose of this study is to investigate the attitude changes of integrated management of urban water/wastewater in the Iran's parliamentary laws since the Constitutional Revolution. During this period, the National Parliament and the Islamic Parliament have ratified eight and ten laws regarding this field, respectively. According to the obtained results, water resources and wastewater collection have been considered more than other sections of the cycle and wastewater treatment sector has had the lowest frequency. In this regard, the main attitude of the laws and the presented solutions have been "political". In addition, before the Islamic Revolution, there were no laws with a "preventive and protective" approach and none of the laws provided an "educational-promotional" solution. However, after the Islamic Revolution, this important and effective approach has been considered in some laws. The initial national authorities for water distribution and treatment were the Municipality and the Ministry of Health, respectively; however, the major responsibilities of this sector were left to the Ministry of Energy since its establishment in 1974. In the first years after the Islamic Revolution, the Ministry of Energy was still responsible for this field and no new authority had been created. About a decade later, the holding of National Water and Wastewater Company formed as the head of authority and the provincial companies were created as its subsets, which was the milestone of integrated urban water and wastewater management in the country; the original nature of this authority has been preserved so far since its formation.

One way to improve cement production is to replace some of it with inexpensive and available additives. Considering the importance of using cement mortars in the construction of masonry structures, the effect of slag produced by Ahwaz Steel Plant, which is a special slag due to significant differences in its chemical composition compared to common slags in the world. The rheological, mechanical and durability properties of mortars were studied. The effect of using slag powder from Ahwaz Steel Plant on the production of cement-slag mortars was investigated. The powder of this slag was replaced with a part of cement at 20% to 70% with 10% increases and the specimens were tested at the ages of 28, 56, 91 and 120 days. Flow table, compressive, flexural, and electrical strength as well as two penetration depth and water absorption tests were performed. The results showed that slag powder at 28 and 56 days of age did not have much effect on the mechanical properties of the specimens, but at 120 days of age the compressive and flexural strengths of specimens containing 20% and 30% of slag powder increased compared to the reference sample; From a technical and economic point of view, 30% is suggested as the optimal replacement percentage. Water absorption at 120 days of age in specimens containing 20% and 30% slag increased by 30% and 61% and water penetration depth of 25% and 33%, respectively, compared to the reference specimen; but the electrical resistance decreased by 11% and 23%, respectively.

Rutting is one of the major deteriorations of asphalt pavement significantly impact on road safety and service quality. Forecasting models are necessary to prevent and control the damage caused by this deterioration in the pavement management system. In this study, using the artificial neural network algorithm, models have been developed to predict the amount of rutting deterioration using the long-term pavement performance (LTPP) database. These models have been developed for wet freeze, dry freeze, and dry no freeze climates. Since proper accuracy and simplicity are the most important features of a prediction model, using the NSGA ІІ-MLP multi-objective optimization method, the more important variables in predicting rutting deterioration are identified and selected as the model input. Then, using traffic, climatic and structural variables selected from the genetic algorithm, rutting deterioration prediction models were developed. The coefficient of determination and the mean squared error for the model made in the wet freeze zone and the common model of dry freeze and dry no freeze zones are equal to 0. 96, 2.05, 0.94 and 3.45, respectively. Also, by performing sensitivity analysis, the effect of input data of each model on rutting deterioration was determined. Among the variables that have the greatest impact on rutting deterioration are the cumulative maximum and minimum daily temperature difference per year, pavement age, asphalt layer thickness, annual equivalent single axle loads, and bitumen penetration.

Sistan and Baluchestan province is located in the southeast of Iran and has a dry and unfavorable climate. The drying up of Lake Hamoon, as well as the 120-day winds, have provided suitable conditions for wind erosion and the occurrence of dust storms, which cause sand dunes to move at high speeds. By locating and constructing windbreaks, the movement of flowing hills can be largely prevented. The purpose of this study is to determine the suitable plant species of the province for the construction of windbreaks and select the optimal sample using the distance-based method. It is important to find the best option for use as a natural windbreak that, in addition to adapting to the climate of the region, has the best response and also does not lead to high costs. In this study, the rate of decrease in wind speed before and after the windbreak and the appropriate distance of its construction from an area were determined by studies. Finally, it was found that Chesh and Kurt, coriander, turmeric, hawthorn and almond trees are suitable for planting in this area. The distance-based method (DBA) defines good values of traits in a process by defining the optimal state. Using this method, it was found that the eye and plum tree is more suitable for constructing windbreaks than other species.

Nowadays, the close confrontation between structure and architecture has led to the invention of new structural systems, such as structural system of Diagrid and Hexagrid. These systems have attracted the attention of many architects and structural engineers due to their structural efficiency and architectural aesthetic potential provided by their unique geometric configuration. Hexagrid structural system has high ductility, and Diagrid structural system has high stiffness. One of the most important principles in the field of high-rise structures is the use of an appropriate structural system that have a significant architecture, in addition to satisfying the three requirements of stiffness, resistance, and ductility in the design of the structure. Therefore, in this thesis, the combination of two systems of Diagrid and Hexagrid at the height of the structure in order to take advantage of their benefits is proposed. For this purpose, four structures of Diagrid, Hexagrid, Diagrid-Hexagrid compound structure and Hexagrid-Diagrid compound structure were analyzed and designed using linear dynamic method with ETABS software. Then, their seismic performance was evaluated with PERFORM 3D software using non-linear static analysis in terms of lateral displacement, stiffness, ductility, lateral resistance and behavior factor. Comparison of the structural analysis results shows that Diagrid-Hexagrid compound structure has a more favorable performance against lateral forces than the two systems of Diagrid and Hexagrid.